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Item Open Access Agronomic evaluation of chickpea (Cicer arietinum L.) genotypes in contrasting agro-ecological regions of Limpopo and Mpumalanga Provinces(2020-02-24) Shilenge, Siphiwe Kim; Ogola, J. B. O.; Odindo, A.Chickpea (Cicer arietinum L.) is an important grain legume in the world, ranking second after soybean (Glycine max L.). It accounts for a substantial proportion of human dietary nitrogen intake and plays a crucial role in food security in developing countries. Chickpea can grow in areas with low rainfall and poor soils, and thus may be an important food security crop for smallholder resource-poor farmers in the semi-arid tropics such as the dry environments of the Limpopo and Mpumalanga Provinces of South Africa. Preliminary studies showed the huge potential of chickpea production in these environments. However, no suitable genotypes have been identified and recommended for different agro-ecological zones of Limpopo and Mpumalanga Provinces. Therefore, the objective of this study was to evaluate the performance, and hence, identify the genotypes that are adapted/suitable to the contrasting agro-ecological conditions of Limpopo and Mpumalanga Provinces for production. Field experiments were conducted in the winter cropping seasons of 2016 and 2017 at Thohoyandou (University of Venda experimental station), Syferkuil (University of Limpopo experimental station) and Nelspruit (University of Mpumalanga experimental station). Ten desi chickpea genotypes were sown in a completely randomized block design replicated three times on 10 May 2016 and 10 April 2017 (Thohoyandou), 13 May 2016 and 11 April 2017 (Syferkuil) and 03 May 2016 and 24 May 2017 (Nelspruit). Plant growth characteristics were assessed by determining plant height, crop phenology, number of primary and secondary branches, and canopy cover. Yield and yield components were assessed at harvest after physiological maturity. Carbon dioxide exchange rates (CER) was determined at different growth stages using the InfraRed Gas Analyzer (IRGA). Chlorophyll content (CC) and intercepted radiation were determined weekly using the chlorophyll content meter (CCM-200 PLUS, Opti-Science, Tyngsboro, Massachusetts), and the AccuPAR, LP-80 ceptometer (Deacon Devices Ltd., Pullman, USA), respectively. Genotypes did not vary in CC at Thohoyandou in all seasons, but CC increased with stages of growth. Genotypes varied in the proportion of intercepted radiation (IR) at all measurement dates in Thohoyandou during the 2016 and 2017 growing seasons. The proportion of IR increased with growth stage, reached a peak and declined with plant age. Genotype affected photosynthesis and intercellular CO2 concentration (Ci) but did not have any significant effect on stomatal conductance (gs), transpiration (T) and Leaf Vapour Pressure Deficit (VPDL) during the 2016 season in Thohoyandou. In contrast, genotype did not affect photosynthesis, Ci, gs, T and VPDL in the 2017 season in Thohoyandou. There was no variation among genotypes on number of primary and secondary branches in Thohoyandou in both seasons. Genotypes showed no variation in plant height in the 2016 season in Thohoyandou agro-ecological condition. However, genotypes showed significant variation in plant height at 14, 70 and 84 days after emergence (DAE) in the 2017 cropping season. Moreover, genotypes showed significant variations in days to 50% flowering in Thohoyandou during the 2016 season, but showed no variations in days to 50% emergence and 75% physiological maturity. Genotypes showed no variations in days to 50% emergence, 50% flowering, 50% podding and 75% physiological maturity in the 2017 season in all locations. Genotypes showed significant variation in grain yield in Syferkuil agro-ecological condition, but showed no significant variations on all the other studied traits, while genotypes varied in 100 seed weight (SW) in Thohoyandou, but did not show any variations on the other studied traits during the 2016 season. Moreover, genotypes did not vary for all studied traits in Nelspruit during the 2016 season. The 2016 genotype and environment (G X E) interaction results showed no significant variations. However, results showed G X E interactions during the 2017 growing season suggesting that genotypes responded to environmental variation in a different way. Syferkuil had the greatest grain yield (2811 kg ha-1 and 3122 kg ha-1) in both the 2016 and 2017 growing seasons respectively, as compared to Thohoyandou and Nelspruit. These preliminary findings show that the studied genotypes responded differently in contrasting agro-ecological regions of Limpopo and Mpumalanga Provinces and that Syferkuil might be the best environment for chickpea production in this region due to its cooler temperatures. Of the genotypes evaluated the most promising genotypes are ICCV8101, ICCV3203 and ICCV4110 in these regions in terms of grain yield.Item Open Access Assessment of hydro-physical properties of some crusting soils in four different soil form as revealed by micro-focus x-ray computed tomography in Limpopo Province, South Africa(2021-06-23) Mpofu, Khuthadzo Tendani Given; Wakindiki, I. I. C.; Odhiambo, J. J. O.Most of the available knowledge about soil structure degradation through crust formation is limited to two-dimensional geometry. However, soil is a natural three-dimension body. The objective of the study is to assess soil crusting and hydro physical properties in four different soil form by using X-ray Computed Tomography, Characterizing micro-morphometric of crusting soil’s pore system, quantifying soil structure degradation through crusting development and visualizing hydro physical properties in all four-soil form. Micro X-ray Computed Tomography techniques can greatly add value to existing knowledge because they can reveal soil structure in three dimensions (3D). Undisturbed soil aggregates were obtained from two adjacent sampling locations namely Visibly Crusted (VC) and Not-Visibly Crusted (NVC). Four soil forms were studied in Limpopo province, South Africa at Vhembe Region under Thulamela and Collin Chabane local Municipality. Soil form studied are Dundee, located at (Tshamutoro village), Shortlands (Mukula Village), Hutton (University of Venda) and Glenrosa (Ha-Davhana village). The samples were scanned using Nikon XTH 225L micro-focus CT X-ray unit. The scans were reconstructed into three-dimensional volume data set of pore shapes, pore size and porosity among the soils using CT Pro software® and further analysed using VG Studio Max V3.0®. images were acquired after 30 minutes in each scan. The result of the study indicated that total porosity decreases with increase in depth, and the shape of the aggregates were dominated by regular pores that are susceptible to water erosion. Moreover, soil pores inform of mesopores, micropores, and macro pores were recorded using 3D images acquired .By visualizing hydro physical properties using images in 2D and 3D, it was possible to visualize arrangement of aggregates and their sizes helping to understand the erodibility of soil. In conclusion X-ray computed tomography is an effective tool to study the microstructure of soil aggregates.Item Open Access Assessment of the effect of fungicides on powdery mildew development on butternut squash(2016-03-10) Mafa, Maite Sarah; Kunjecu, E. C.; Samie, A.Item Open Access Biochar and Poultry Litter Effects on Maize Growth, Nutrient Uptake and Selected Soil Biological Activities in Different Soil Types(2022-07-15) Ntsoane, R. L.; Odhiambo, J. J. O.; Kutu, F. R.; Kutu, F. R.South African soils contain lesser percent organic carbon content compared to soils from many parts of the world. The loss in organic carbon content reduces soil fertility and drives an ever increasing demand for the use of soil amendments to enhance soil fertility. The study consiststed of a greenhouse pot experiment and a laboratory incubation experiment. The objective of a greenhouse study was to assess the effects of biochar and poultry litter application on maiize productivity under different soil types. Treatments consisted of different soil types and amendments of biochar and poultry litter. Soils were collected from four sites (Mutshenzheni, Rambuda, Tshiombo Irrigation and Tshiombo Madzivhandila) representing different soil types (Westleigh (We1), Hutton (Hu), Westleigh(We2) and Shortlands (Sd), respectively. Soils were amended with biochar and poultry litter. The amendments consisted of various mix ratios of biochar (BC) with poultry litter (PL) as treatments, which are namely, BC0PL0, BC100PL0, BC75PL25, BC50PL50, BC25PL75, and BC0PL100. Soil amendments were applied at different rates of 0- 5 t ha-1 PL and 0- 40 t ha-1 BC. Treatments were laid out in a completely randomize design (CRD) and replicated three times. Biochar and poultry litter application exerted no significant difference on soil pH of We2, Sd, and Hu soils. However, the effect of biochar and poultry litter application was significant at soil We1. In contrast, application of biochar and poultry litter had no effect on soil total N of soil We1, We2, and Hu and was significant on soil Sd. The results of this study showed that application of biochar and poultry litter treatments had no significant effect on both the maize growth and nutient uptake at early stages ( Week 1 and Week 2). However, the application of biochar and poultry litter treatments had a significant difference ( p ≥ 0.001) on maize growth and nutrient uptake at a later stage ( Week 3 to Week 6). Therefore, there is a potential to ameliorate fertility constraints in agricultural soils using biochar combined with poultry litter. Though biochar possesses some essential elements required for plant growth, sole application reduces its efficiency with its effectiveness confirmed only when applied in combination with organic-based materials such as poultry litter. The laboratory incubation experiment assessed the effects of different biochar rates on soil chemical and bio-quality parameters. Each treatment consisted of a 200 g of soil (We1, Hu, We2 and Sd) homogenously mixed with biochar amendments (0, 10, 20, and 40, t ha-1). The treatments were laid in a completely randomize design (CRD) and replicated three times. Soil sampling was done on day 0, 30, 60, 90, and 120, and samples were analyzed for soil available P and N and bio-quality parameters namely microbial biomass nitrogen, microbial biomass carbon, urease, alkaline and acid phosphatase, β glucosidase, soil organic carbon, and dehydrogenase activity. The results of the study revealed various responses of soil bio-quality parameters and selected soil chemical properties after biochar and poultry litter application. Thus, the effects of biochar rate, incubation days and soil type on soil enzymes and other bio-quality parameters elicited an understanding on microbial activity and soil enzymes mechanism . Therefore, a prolonged study (more than 120 day) is required to evaluate the effects of incubation days, biochar rate and soil type effect on soil nutrients and bio-quality parameters.Item Open Access Biochar and poultry manure effects on selected soil physical and chemical properties and maize (Zea Mays) in a dry environment(2018-05-18) Musumuvhi, Thabelo; Odhiambo, J. J. O.; Mzezewa, J.Poultry manure (PM) is an inexpensive source of fertilizer but it decomposes quickly and releases carbon and greenhouse gases. Biochar (BC) could be an alternative source of carbon to improve soil quality and reduce greenhouse gas emission. This study investigated the effect of co-application of BC and PM on selected soil physical and chemical properties and performance of maize. A field experiment was conducted at the University of Venda experimental farm during 2015/2016 and 2016/2017 seasons. The experiment was a 4 x 3 factorial arrangement consisting of four rates of BC (0, 5, 10 and 20 t ha-1) and three rates of PM (0, 2, and 4 t ha-1) in a RCBD arrangement replicated three times. Maize was planted in both seasons. After harvest, soil bulk density was determined at four soil depths (0-5, 5-10, 10-15, and 15-20 cm), while aggregate stability and selected soil chemical properties were determined at two soil depths (0-15 cm and 15-30 cm). Data were subjected to ANOVA using Genstat 17th edition. The least significant difference was used to compare the treatment means at P < 0.05. Soil aggregate stability, organic carbon, Ca2+, Mg2+, K+, maize dry matter and maize grain yield increased with increasing rates of BC and PM application at 0 - 15 cm depth in both seasons. The combination of BC at 20 t ha-1 and PM at 4 t ha-1 significantly (P < 0.05) decreased soil bulk density at 5 - 10 cm depth but increased soil available P and total N at the two depths in both seasons. The results of this study suggested that BC and PM improved soil ability to retain and supply nutrients through improved soil aggregate stability and reduced bulk density thereby improving maize dry matter and grain yield. Combining BC with PM proved to enhance the ability of soil to function by improving selected soil physical and chemical properties thereby improving maize dry matter and grain yield.Item Open Access Chickpea nitrogen fixation, rhizosphere nutrient concentration and contribution of residual nitrogen to improve maize production in response to biochar application in three different soil types(2022-07-15) Lusiba, Siphiwe Gloria; Odhiambo, J. J O.; Adeleke, R.; Maseko, S. T.Soil degradation is a major challenge affecting agricultural production around the world in the twenty-first century. Alternative approaches including the use of biochar and the introduction of legumes that will fix nitrogen though the process of biological nitrogen fixation (BNF) are essential for improving soil quality of current low productive soils, thus increasing crop yields, and maintaining food security while conserving the environment. To address this problem, three experiments were conducted in this study. First, two locally produced biochar from poultry litter and acacia feedstocks were assessed whether they qualify as ‘biochar’ for use as soil amendment according to the international biochar bodies. Secondly, a pot experiment was then conducted to investigate the potential impact of poultry litter biochar (PLB) and acacia biochar (ACB) to improve rhizospheric soil nutrient availability, bacteria abundance and diversity, chickpea growth and total nitrogen fixation in three contrasting soil types. Thirdly, another pot experiment was conducted to determine the contribution of residual N from biochar and N-fixed by chickpea to the following maize crop grown in three contrasting soil type. The treatments consisted of three soil types classified as Fernwood [Arenosol]; Pinedene [Gleyic Acrisol]; Griffin [Helvic Acrisol], sampled from three different smallholder farmers at Dopeni village, Limpopo Province. The two biochars [PLB and ACB] were applied at four application rates of [0% (control), 0.5, 1 and 2% w/w]. The treatments were arranged in a completely randomized design and replicated four times. For the first experiment, chickpea (Cicer arietinum) desi cultivar was inoculated and grown for 65 days in soils with uniformly applied P at 60 kg P/kg in all pots and water maintained at 60% field capacity. For the second experiment, maize (Zea mays) was grown for 95 days in the same soil as chickpea and biochar treatments as well as after harvesting maize that was used as a reference crop. Biochars made from poultry litter and acacia feedstocks meet the International Biochar Initiative (IBI) and European Biochar Certificate (EBC) requirements and qualifies as biochar for use as a soil amendment. Both biochars had C content greater than 50%, with H/C and O/C ratios less than 0.6 and 0.4, respectively, indicating that both biochars are stable for C sequestration and can remain in the soil for about 1000 years. Because poultry litter biochar (PLB) contained more nutrients than acacia biochar (ACB), PLB improved rhizospheric pH, CEC, and nutrient concentration (N, P, K, and Ca) when applied at 0.5-2% in the Griffin and Pinedene soils, resulting in higher biomass production and nutrient uptake of chickpea. In addition, when 2% PLB was applied to those two soils, bacteria capable of fixing N, especially those from the phylum Proteobacteria, were more abundant. Thus, chickpea grown in these soils and at these PLB rates derived more N from the atmosphere, fixed more N, and xvi accumulated more N and C in the shoot, but was less water use efficient. Furthermore, maize grown in 1% residual PLB treatments produced more biomass and accumulated more N and other nutrients than maize grown with 0.5-2% residual ACB treatments. However, when grown after chickpea harvest in residual PLB treatments of 2% in the Griffin and Pinedene soils, maize produced greater biomass and accumulated more N and other nutrients. Application of PLB and ACB at 0.5% in the Fernwood soil was ideal to improve rhizospheric nutrient availability, the abundance of bacteria communities [from the phylum Proteobacteria, Acidobacteria, and Firmicutes which are important for C and N cycling and bioremediation], as well as growth, BNF, and C accumulation of chickpea, including maize growth and nutrient uptake in monocropping or in rotation with chickpea. The greatest variation in relative abundance of bacteria communities and growth of chickpea was due to the substantial change in soil pH and rhizospheric nutrient availability such as N, P, K, and Mg, while biomass production and N accumulation were largely attributed to the improved BNF and C accumulation of chickpea in the clay textured soils. The increased growth and nutrient uptake of the following maize crop in the Griffin and Pinedene soils was attributed to high N inputs through BNF and biochar mineralisation, whereas the variation in bacteria communities, chickpea and maize performance in the Fernwood soil was due to the change in rhizospheric soil pH, P, and K. The findings of this study conclude that biochar made from poultry litter is recommended for use as a soil amendment to improve nutrients and soil quality, although caution should be taken when applied at higher rates (40 t/ha) as it may immobilize N or result in high release of toxic elements. Furthermore, incorporating chickpea into existing maize cropping systems of smallholder farmers and using biochar made from poultry litter will help reduce nitrogen input costs by adding residual nitrogen from biochar mineralisation and through BNF, improving soil quality and maize production. On the other hand, biochar made from acacia feedstock will be excellent for use to improve soil organic carbon and water adsorption, but it should be applied months before planting or supplemented with high organic N and P materials when used as a soil amendment to improve nutrient availability, as it may temporary fix N and P in the soil. When using poultry litter or acacia biochar on a poorly buffered loamy sand soil like the Fernwood, care should be taken to avoid over liming, which can cause nutrient deficiency and negatively affect nutrient uptake. Moreover, to improve chickpea and maize performance in sandy textured, highly leached soils like the Fernwood, biochar should be applied regularly or combined with organic materials to improve soil organic carbon to allow the soil to retain and release nutrients for plant uptake.Item Open Access Combining Ability for Ear Prolificacy and Response of Prolific Maize (Zea May L.) Hybrids to Low Nitrogen Stress(2018-09-21) Makhumbila, Penny; Gwata, E. T.; Mashingaidze, K.Smallholder farmers in Sub-Saharan Africa still obtain low grain yields in maize largely due to low soil fertility. The soils are inherently low in nitrogen (N) that is required for the proper development of the maize plant. Currently there are no commercial cultivars for low N tolerance locally. The combining ability approach can be used as a tool for breeding desirable cultivars. In order to improve grain yield in maize, it is important to consider ear prolificacy which is a major yield component. Therefore this study was designed to estimate combining ability in maize. Exotic germplasm from the International Maize and Wheat Improvement Center and the Institute of Tropical Agriculture as well as the local germplasm from the Agricultural Research Council was used in the study to generate crosses. One hundred and two crosses were evaluated together with a standard commercial check under low N and optimum N conditions. The specific objectives of the study were to determine general and specific combining ability for prolificacy among local and exotic inbred lines and evaluate the response of prolific hybrids to low N conditions. The hybrids were planted in the 2014/2015 summer season under irrigation in Potchefstroom, Cedara and Taung in field plots consisting of 0.75m x 0.25m spacing in a 0.1 alpha lattice design replicated twice. Data for agronomic attributes were recorded and subjected to analysis of variance using SAS version 9.1.3. Genetic correlations were analyzed using the Principal Components Analysis and factor analysis based on the correlation analysis and major traits. The results showed variation in agronomic performance among the inbred lines and their F1 hybrids. Inbred lines including TZEI63, T1162W, L15 and L17 showed positive GCA estimates for ear prolificacy at the different locations. Specific combining ability for prolific hybrids was positive at all locations and environments. The GCA:SCA ratio was close to unity; indicating that the number of ears per plant showed highly significant (P<0.01) correlation with grain yield. The hybrids showed ear prolificacy under the low N conditions. This trait can be used effectively in stress tolerance maize breeding programmes.Item Open Access Conservation agriculture and slope position effect on selected soil physical properties of a Vertisol at Tshivhilwi in Limpopo Province(2023-10-05) Tshilonga, Mushe Moses; Mzezewa, J.; Odhiambo, J. J. O.Conservation agriculture (CA) is a production system that involves three principles which are minimal or zero tillage, crop rotation and mulching with plant residues. CA improves soil physical properties resulting in soil fertility improvement. However, there are relatively few studies that have documented the benefits of CA on soil physical properties of vertisols. A study was conducted to determine the influence of CA and slope position on soil bulk density (BD), total soil porosity (Vf), soil aggregate stability (AS), soil water holding capacity (WHC), soil organic carbon (SOC), soil electrical conductivity (EC), infiltration rate (IR) and cumulative infiltration (CI) of a vertisol, at Mutanga Wa Ndodzi Agricultural Co-operative at Tshivhilwi village where CA has been in practice since 2013. The farm practices CA with crop rotation. The field used for CA was tilled once in 2013 using a mouldboard plough. Mulching is done using maize stalks. After planting fertilizer was applied based on crop requirement. One set of soil samples were collected from a field under CA while another set was collected from a field under natural grass (control) which is located directly opposite the CA field. Soil samples were collected 10 m apart from 0-10 and 10-20 cm depths along the transects which were at, 10 m apart. A core of diameter of 5 cm and height of 5 cm was collected to determine soil BD. SOC was determined using the modified Walkley-Black wet oxidation procedure. EC was measured with glass electrode professional EC meter in 1:5 ratio soil water suspension. Soil AS was determined using wet sieving method. Soil particle density was determined using a pycnometer bottle after which the bulk density and particle density of the soil were used to calculate soil porosity. Soil WHC was determined by saturating with water 25 g of oven-dried soil in a glass funnel and its water holding capacity determined by gravimetric method. Management and slope position interaction had a significant effect at 0-10 cm and 10-20 cm soil depth with lower BD at the CA site lower slope position at 0-10 cm soil depth. SOC was significantly higher on lower and middle slope of CA than natural grassland (NG) site. The CA site x recorded higher EC at the middle and lower slope positions compared to NG site. Higher AS was observed at the CA site than NG at all slope position at 0-10 cm soil depth, at 10-20 cm CA site recorded higher AS at the lower and middle slope. Vf was significantly higher at the CA site than NG site at all slope positions, CA lower slope was associated with higher Vf followed by middle and summit slope. CA site exhibited a higher WHC than NG site at all slope positions, CA middle lower slope positions had the highest WHC. Interaction effect was observed on final IR however, the significant difference between the two-management system was observed at lower and middle slope. Conservation agriculture and slope position interaction in this research resulted in significantly higher BD, SOC, EC, AS, vf and WHC but had no effect on BD middle slope and summit slope positions at 0-10 cm, SOC summit and lower slope positions at 10-20 cm soil depth, EC summit slope at 0-10 cm, vf at summit and middle slope at 10-20 cm soil depth and WHC lower slope lower slope position at 10-20 cm soil depth. According to the findings of this study, practicing conservation agriculture in various slope positions could be recommended to improve soil properties (bulk density, soil organic carbon, soil electrical conductivity, aggregate stability, total soil porosity, water holding capacity and infiltration rate) of a Vertisol.Item Open Access Distribution of retroacizzia Mopani and its natural enemies in Tshikundamalema Area, Limpopo Province, South Africa(2017-09-18) Mmbengeni, Rofhiwa Isaac; Kunjeku, E. C.; Hurley, B. P.Colophospermum mopane (Fabaceae), commonly known as mopane tree, is an indigenous tree species in Southern Africa, often being the dominant species in semi-arid areas. It plays an integral part in the improvement of communities’ livelihoods when it is harvested for firewood and mopane worms which are edible insects are collected from the tree. Colophospermum mopane is host to many insects, among them Retroacizzia mopani, a leaf pest. Retroacizzia mopani produces lerps which are protective exudates that shield the insect from predation, but lerps also reduce the photosynthetic area of mopane leaves. This study aimed to determine the distribution of the African mopane psyllid, R. mopani and its natural enemies in the Tshikundamalema area, in Limpopo Province. The study assessed the presence of lerps on C. mopane, as well as determining the effect of site, tree height, tree density, tree position, branch size and neighbouring trees on R. mopani infestations at three sites. Sample of leaves infested with R. mopani were collected at six different sites and reared in the laboratory to determine the prevalence of R. mopani natural enemies and the levels of parasitism. The site, tree density, tree position, and branch size had an effect on the R. mopani infestations. The results showed that as the tree density, tree height and branch size increased, R. mopani infestation also increased. Neighbouring trees had no effect on R. mopani infestations. Trees found at the edge of the forest were more heavily infested compared to those that were inside the forest. All the three sites had low levels of parasitism by the natural enemy, Psyllaephagus arytainae Prinsloo. This indicates that P. arytainae has little effect on population dynamics of the psyllids.Item Open Access Diversity of fungi associated with dieback of Ziziphus Mucronata in Limpopo Province, South Africa(2020) Thaphathi, Polly; Kunjeku, E. C.; Ogola, J. B. O.; Coetzee, M. P. A.Ziziphus mucronata (buffalo thorn, Rhamnaceae) is an indigenous tree that serves multipurposes to rural communities and wildlife across Africa. The tree is considered important because of its useful parts for various purposes. For example, leaves of this tree can be consumed as a vegetable by humans and wild animals such as antelopes and baboons feed on them. Fruits from Z. mucronata are edible and nutritious to both human and wild animals such as monkeys. Roots from this tree are used for medicinal purposes by people living in rural areas for treatment of wounds, snake bites, swelling glands as well as diarrhoea. However, the tree face diseases such as dieback that negatively affect its production and there is little research on diseases of Z. mucronata in South Africa. This study was conducted in Limpopo Province, in three different sites namely Tshikundamalema, Buzzard Mountain Farm and Wits Rural Facility to identify fungi from branches of Z. mucronata showing dieback symptoms. Symptomatic branches were collected from each site and processed in the laboratory before primary isolations. Isolates obtained from the samples collected were identified based on their morphology where isolates were grouped according to their morphological characteristics such as colour and structure of mycelia. The isolates were further identified based on DNA sequence data from multiple genome regions including the internal transcribed spacer (ITS), beta-tubulin (BT) and the translation elongation factor (TEF) genomic regions and phylogenetic analyses. Fungi identified in this study were from families Botryosphaeriaceae, Diaporthaceae, Cytosporaceae (=Valsaceae), Nectriaceae, Pleosporaceae and Didymellaceae. Fungi identified include Dothiorella (=Spencermartinsia), Diplodia, Botryosphaeria, Neofusicoccum, Fusarium, Diaporthe (=Phomopsis), Cytospora, Didymella (=Phoma) and Alternaria. Results obtained from this study showed the diversity of fungi associated with dieback of Z. mucronata in Limpopo Province. Studies in other parts of Limpopo Province are needed to further investigate the diversity of fungi found on branches of Z. mucronata with dieback.Item Open Access Effect of biochar and phosphorus fertilizer application on selected soil properties and agronomic performance of chickpea (Cicer arietium)(2015-05) Lusibisa, Siphiwe Gloria; Odhiambo, J. J. O.; Ogola, J. B. O.See the attached abstract belowItem Open Access Effect of biochar and rhizobium innoculation on nodulation, chlorophyll content, growth and yield of chickpea (Cicer arietinum L.)(2018-05-18) Macil, Patricia J.; Ogola, J. B. O.; Odhiambo, J. J. O.Soil infertility, water scarcity, and availability of high yielding and drought tolerant crop genotypes remain major constraints for agricultural production in semi-arid regions. These constraints are major threats to sustainable crop production and food security. Management practices in such areas should always be geared towards improving productivity at a low cost while sustaining soil fertility. Preliminary studies showed the huge potential of chickpea in the dry environments of the North Eastern South Africa. However, lack of nodulation in chickpea has been reported in these regions probably due to low soil pH, insufficient rhizobial populations or total lack of infective native rhizobia. Therefore this study assessed the effect of biochar and rhizobium inoculation on soil pH, nodulation, growth, yield and chlorophyll content of chickpea in Mpumalanga (Nelspruit) and Limpopo (Thohoyandou) Provinces, South Africa. Two field experiments were planted during winter 2015 and 2016. Treatments consisted of three levels of biochar (0, 10 and 20 t ha-1), two Rhizobium inoculation levels (with and without Rhizobium inoculation) and three chickpea genotypes (ACC #4, ACC #5, and ACC #6) in a factorial combination arranged in randomized complete block design replicated three times. Crop phenology (days to 50% emergence, flowering, podding, and physiological maturity), crop growth (plant height, canopy cover, number of primary and secondary branches), nodulation (number of nodules per plant and nodule dry weight), yield and yield components (number of pods per plant, number of seeds per pod and 100 seed weight [100-SW]), and chlorophyll content were determined at various crop growth stages. Identification and isolation of native rhizobia from soils was done using standard protocols. Data obtained were subjected to analyses of variance using the general linear model of Genstat software version 17. Significant differences between the treatments means were compared using the standard error of difference (SED) of the means at 5% level. Correlation analyses were performed to assess the relationship between parameters. Molecular data was subjected to BLASTn in National Centre for Biotechnology Information (NCBI) searches for identification of isolated strains Application of biochar at 10 and 20 t ha-1 increased soil pH by 0.7 pH units in Thohoyandou (clay soil) in 2015 and 2016, respectively. Soil pH increased by 0.77 pH units at 10 t ha-1 and 1.2 pH units at 20 t ha-1 in Nelspruit (loamy sand) in 2015 and 2016, respectively. Similarly, rhizobium inoculation increased soil pH by 0.2 (Thohoyandou) and 0.5 (Nelspruit) pH units in 2015 and 2016, respectively. There was a 100% increase in nodulation in inoculated compared to uninoculated treatments. There was no effect of biochar and rhizobium inoculation on number of days to 50% flowering, podding, v physiological maturity and on plant height. However, plant height varied with genotypes. Biochar application increased above ground biomass by 17% (10 t ha-1) and 12% (20 t ha-1), and 100 seed weight by 9% (10 t ha-1) and 7% (20 t ha-1) in Thohoyandou in 2015. Rhizobium inoculation increased yield and yield components in Thohoyandou in both seasons; biomass was greater by (31 and 23%), grain yield (26 and 24%), number of pods per plant (18 and 31%), and 100-SW (10 and 13%) in 2015 and 2016, respectively. Similarly, rhizobium inoculation increased biomass (53.4%), grain yield (81%), number of pods per plant (54%) and number of seeds per pod (89%) in Nelspruit in 2015. Genotype did not affect yield and yield components in Nelspruit. In contrast, genotype affected above ground biomass, grain yield, harvest index, number of pods per plant, and number of seeds per pod in 2015 in Thohoyandou with ACC #6 producing greater yield compared to ACC #4 and 5. The analysis for native rhizobia showed that agricultural fields in Nelspruit and Thohoyandou lack effective strains of rhizobium. The identified strains according to 16s gene region were Klebsiella variicola, Burkholderia cenocepacia, Bacillus subtilis and Ochrobactrum spp. The effects of biochar and rhizobium inoculation were more pronounced in Thohoyandou compared to Nelspruit. Therefore biochar and rhizobium inoculation may improve chickpea productivity in Limpopo and Mpumalanga Provinces through improved soil pH, nodulation, growth, yield and yield components.Item Embargo Effect of biochar derived from different feedstocks on nitrogen retention availability, and uptake by a maize crop(2024-09-06) Khethani, Thakhani; Odhiambo, J. J. O.; Lusiba, S. G.Nitrogen (N) is an essential nutrient for most crops and can be provided directly by fertilisation or indirectly through atmospheric deposition, fixation, all of which can then be converted to nitrate through mineralization and nitrification. Incomplete N utilisation by crops leaves residual soil nitrate, which is water soluble and susceptible to leaching into groundwater, particularly in regions dominated by light-textured sandy soils with low WHC. Application of biochar (BC) can potentially have a significant impact on nitrogen retention and availability. BC is a charcoal-like substance that’s made by burning organic material from agricultural and forestry wastes (also called biomass) in a controlled process called pyrolysis. Biochar can increase organic matter content, act as a liming agent, add basic cations and micronutrients, improve water holding capacity, and release nutrients gradually to the growing plant. This study evaluated the effect of BC derived from different feedstock on nitrogen retention and availability. Two experiments’, laboratory (column leachate) and nursery experiments were conducted at the University of Venda Soil Science Laboratory and the School of Agriculture Experimental Farm, respectively. The treatments in both experiments 1 and 2 consisted of a factorial combination of BC from three different feedstocks (acacia, hay, and poultry litter) and three BC application rates (0%, 1%, and 2%). In experiment 1, the levels of NH4+ and NO3- leached from and retained in the soil were determined in the laboratory experiment before and after 70-day leaching period. The columns were first filled with three kilograms of the soil-BC mixture based on the previously mentioned treatments, giving rise to an initial bulk density of roughly 1.5 g/cm3. A single fertiliser application with 100 mg of solutioned ammonium nitrate (NH4NO3) was applied to each column. The fertilizer was applied to each column's surface in uniform drips after being diluted in 5 millilitres of distilled water. In the laboratory, the columns were maintained at room temperature, or roughly 23 °C. Every two weeks, 200 ml of distilled water was added to each column through a funnel that was placed above the center of each column. To aid in the dispersal of the water drips, filter papers were placed on the soil surface of the columns. Columns were allowed to drain freely during the leaching process, and all leachate samples were collected in foil-wrapped Erlenmeyer flasks to minimize evaporative loss. For 10 weeks (seventy days), columns were leached every two weeks. Every two weeks, the leachates were collected and chilled before analysis to minimize the growth of algae. Leachates were collected every two weeks, and the pH and electrical conductivity (EC) were measured. The leachate samples were then filtered through Whatman No. 42 filter paper to measure the amounts of nitrite (NO3-) and ammonium (NH4+). In experiment 2, which was conducted in a nursery, 5 kg of soil was placed in pots measuring 25 cm in height and 25 cm in diameter. Maize (Zea mays L.) was used as a test crop and harvested 56 days after planting. xviii The measurements made in this experiment were dry matter (kg) and nitrogen uptake (kg/ha). A uniform application of nitrogen fertilizer (LAN) at a rate of 100 kg N/ha was given to each pot. The soils were treated with BC as per the stated application rates and ammonium nitrate fertilizer one week prior to planting. The treatments were arranged in a completely random design (CRD) The pots were wetted to 60% field capacity (FC) and allowed to dry out for 24 hours prior to planting. Three maize seeds were planted in each pot. After watering, the pots were filled to 60% of their field capacity (FC). After being allowed to develop for a maximum of eight weeks (56 days), maize crops were collected, dried, weighed, ground, and the N content determined. In experiment 1, the current study's findings show that using BC can significantly reduce the leaching of highly mobile nutrients like NH4+ and NO3-. The total amount of leachates collected increased by 46% and 42% at the 1% and 2% biochar application rates, respectively. The amount of ammonium and nitrate retained increased by 1.62% and 16.2% at a 2% rate of application, respectively. In comparison to the control, where no BC was added, BC significantly reduced ammonium leaching at 1% on days 56-70 and 2% (w/w) in BC-amended soils. Biochar increased EC in all BT and retained NH4+ and NO3-. In experiment 2, this study has shown that feedstock type significantly affects biomass accumulation and N uptake. Biomass yield and N uptake increased in the order poultry litter > acacia > hay. Increasing biochar rates from 0 to 2% increased biomass accumulation and N uptake. In summary, biochar type and rate of application have a potential effect on N leaching and retention in the soil, as well as the biomass and N uptake and therefore these factors should be considered when biochar is used as a soil amendment, especially for N management in agricultural systems.Item Open Access The effect of biochar on immobilization and phytoavailability of chromium, nickel and lead in soils amended with slag(2020) Letsoalo, Morakene Lambert; Odhiambo, J. J. O.; Lukhele-Olorungu, P.Application of industrial wastes in agricultural fields as sources of plant nutrients has become a common practice in agriculture. In other countries and recently South Africa, steel plant slag (SPS) (an industrial waste) is used in agricultural fields as liming material. Steel plant slag is a potential source of plant nutrients, especially in areas where plant iron chlorosis is a problem. The use of SPS as liming material on agricultural soils seems viable despite the detrimental effects due to heavy metals contained in SPS. The presence of heavy metals [chromium (Cr), nickel (Ni) and lead (Pb)] in higher concentrations in potential agricultural soils has negative effects to fauna and flora. Naturally soils possess traits that counter the accumulation of heavy metals, for example, texture and pH of a soil can play a role in the adsorption of heavy metals. An alternative strategy would be that capable of enhancing the metal-binding capacity of soil amendments such as biochar. In this study, the aim was to evaluate the effect the different types of texture, the efficacy of different types of biochar and rate of biochar on the concentration of chromium, nickel and lead. The greenhouse pot experiment was therefore conducted to investigate the effect of biochar on the immobilization and phytoavailability of chromium, nickel and lead in soils amended with slag. A 2 x 2 x 4 factorial experiment was conducted with three factors consisting of two soils (sandy and clay), two biochar and four biochar rates (0 t/ha, 5 t/ha, 10 t/ha, and 20 t/ha). All the soil and biochar were thoroughly mixed. 4 kg of soils was placed in a pot. Slag was then applied to each pot at an amount equivalent to 15 g/kg (75 g per pot). The treatments were replicated four (4) times to give a total of 64 pots and were arranged in a completely randomized design (CRD) in a greenhouse. The soils were analyzed for texture, exchangeable cations (Mg2+, Ca2+, K+), pH, electrical conductivity and soil aggregates. Slag was analyzed for potassium, phosphorus, pH, electrical conductivity, total nitrogen, chromium, nickel and lead, and biochar was analyzed for organic carbon content, pH, electrical conductivity, calcium, magnesium, potassium and phosphorus. The data showed that acacia and poultry litter biochar significantly (P< 0.01) immobilized and reduced the phytoavailability of Cr, Ni and Pd in the soil. For example, the application of 20 t/ha biochar in this study significantly decreased the concentrations of chromium, nickel and lead. The biochars immobilized the selected heavy metals from a range of 9.3% to 89.9% and reduced the phytoavailability from a range of 0.0248% to 8.1x10-8%. Acacia and poultry litter biochar significantly increased the shoot dry biomass of spinach plant by 1.2% to 85.1%. Following the application of biochar to the soil, electrical conductivity and pH increased significantly (P< 0.01) from 24% to 22% and 11.3% to 44.7% respectively. Application of acacia and poultry litter biochar significantly (P <0.01) increased soil stable aggregates by 14.3% to 43.5%. Application of acacia and poultry litter biochar reduced the toxicity of heavy metals (chromium, nickel and lead) in spinach by immobilizing and reducing phytoavailability of the heavy metals. Acacia and poultry litter biochar have positive effects on the soil pH, electrical conductivity, plant growth (shoot dry biomass of spinach) and soil stable aggregates.Item Embargo Effect of biofertilizers on phosphorus nutrition and grain yield of des chickpea (Cicer arietinum L.) grown in different agro-ecologies(2024-09-06) Mashishi, Sina; Ogola, J. B.O.; Odhiambo, J. J. O.; Maseko, S. T.South African soils are predominantly acidic and have high levels of Al and Fe, giving a higher P sorption capacity and low P levels. Consequently, soil fertility has become a major constraint in South Africa’s farming, thereby threatening crop production and food security. Literature reveals, however, that biofertilizers have the potential to improve crop growth, grain yields and, acid and alkaline phosphatase activities in both the plant tissue and soil. Nonetheless, there is scant information about the biofertilizers’ effects on their co-application with rhizobium inoculation as most of the studies focused on the sole application of the biofertilizers such as Bontera, Kelpak, Mycorrhiza, and Rhizobium inoculation. This study evaluated the biofertilizers’ effects on the phosphorus accumulation in the rhizosphere soil, the acid and alkaline phosphatase activity in the rhizosphere soil and, the two chickpea genotypes’ growth and yields under different environments. In 2019, three field experiments were conducted in three locations, namely Thohoyandou, Syferkuil, and Sikhwahlane, and two more were done at Thohoyandou and Syferkuil in 2021. The treatments consisted of a factorial combination of six biofertilizer levels (Mycoroot, Kelpak, Rhizobium inoculation, Kelpak+Rhizobium inoculation, Mycoroot+Rhizobium inoculation, zero control) and two chickpea genotypes (Accession 3 and Accession 7). These were arranged in a three-time replicated randomised complete block design. The intercepted radiation’s (IR) proportion was measured using the AccuPAR LP-80 ceptometer at Thohoyandou in 2019 and 2021. The chlorophyll content was measured at vegetative and reproductive stage using a chlorophyll meter (CCM-200 PLUS, Opti-Science) at Thohoyandou and Syferkuil in 2021. The stomatal conductance (gs) was measured using a portable porometer (AP4 DELTA-T Device) at the vegetative and reproductive stage at Thohoyandou in 2021. The normalised different vegetation index (NDVI) was measured using the portable GreenSeeker at the vegetative stage at Thohoyandou and Syferkuil in 2021. The chlorophyll fluorescence was measured at the flowering stage using the portable chlorophyll fluorometer at Thohoyandou, Syferkuil, and Sikhwahlane in 2019; and at Thohoyandou and Syferkuil in 2021. The acid and alkaline phosphatase activities were measured at the flowering stage at Thohoyandou, Syferkuil, and Sikhwahlane in 2019, and at Thohoyandou and Syferkuil in 2021. The inorganic phosphorus was measured at the flowering stage at Thohoyandou and Syferkuil in 2021. The yield and yield components (pod weight, shoot biomass, and harvest index) were measured at the harvest maturity stage at Thohoyandou, Syferkuil, and Sikhwahlane in 2019, and at Thohoyandou and Syferkuil in 2021. Data were analysed for variance (ANOVA) using the STATISTIX (2017) version 10.0. The Tukey’s honestly difference (HSD) test was used to separate the means that were significantly different (P≤0.05). The Pearson correlation was used to test the linear association’s strength between the parameters studied. The biofertilizers significantly increased the intercepted radiation’s proportion (%IR) at Thohoyandou in 2019 and 2021. The Kelpak sole and in combination with the rhizobium inoculation on 61DAE (86.71) and 75DAE (85.10) recorded the highest %IR in 2019 cropping season. The rhizobium inoculation recorded the highest %IR at 47DAE (50.17) & 83DAE (80.67) and the Kelpak+Rhizobium inoculation recorded the highest %IR at 61DAE (54.33) & 75DAE (68.67) in the 2021 cropping season. The genotype had no significant effect on %IR in both seasons but the interaction between M x accession7 gave the greatest proportion of the intercepted radiation in 2019. The chlorophyll content was significantly increased by the biofertilizers at Thohoyandou (clay soil) only in 2021 with the Kelpak combined with rhizobium inoculation recording the greatest chlorophyll content (2.13-3.10) in all measurement dates. However, the genotype affected the chlorophyll content at 74DAE with accession7 recording the highest chlorophyll content compared to accession3. However, the interaction between the biofertilizer and the genotype had no significant effects on the chlorophyll content in all sites. The stomatal conductance was significantly affected by the biofertilizer application with K+R recording the highest gs at 42DAE (529.25) and M+R recording the highest gs at 56DAE (473.08) at Thohoyandou in 2021. Both the genotype and interaction between the biofertilizer and the genotype significantly affected the gs at 70DAE with accession3 recording the highest gs compared to accession7, and the Mycoroot x accession3 recording the highest gs. The normalised difference vegetative index was significantly increased by the biofertilizer application at 28DAE & 42DAE at Syferkuil only (sandy soil) with Mycoroot and K+R recording the highest NDVI at 28DAE (0.56) and rhizobium inoculation and M+R recording the highest NDVI at 42DAE (0.68). Neither the genotype nor the interaction between the biofertilizer and the genotype had a significant effect on the NDVI in all sites. The biofertilizer’s application significantly affected the acid and alkaline phosphatase activities in all sites except at Syferkuil in 2021 where the biofertilizers had no significant effect on the alkaline phosphatase activity. The co-application of K+R gave the highest APase at Syferkuil (sandy soil) and Sikhwahlane (loamy soil) in 2019, while at Thohoyandou (clay soil) the co-application of M+R gave the highest APase. In 2021, the co-application of K+R gave the highest APase at Syferkuil and Thohoyandou. The alkaline phosphatase activity was higher with the application of rhizobium inoculation at Syferkuil and Thohoyandou in 2019, and higher with the co-application of M+R (13.03) in Sikhwahlane in 2019. However, the zero control gave the highest AlkPase activity (74.14) at Syferkuil in 2021. At Thohoyandou (2021), however, the Kelpak’s application recorded the highest AlkPase activity (56.81). Inorganic phosphorus was significantly affected by the biofertilizers in both sites. The co-application of K+R recorded the highest inorganic phosphorus at Syferkuil and the sole Kelpak (15.16mg/kg) gave the highest inorganic phosphorus at Thohoyandou in 2021. The genotype had no significant effect on the APase and AlkPase activities but significantly affected the inorganic phosphorus at Syferkuil with accession3 (55.61mg/kg) recording the highest Pi compared to accession7. The interaction between the biofertilizer and the genotype affected the APase and inorganic at Thohoyandou, and only the Pi at Syferkuil in 2021. Among the various biofertilizers used at Thohoyandou, the rhizobium inoculation recorded the highest quantum yield of PSII (0.24 to 0.33) in 2019. The biofertilizers, however, significantly affected the PSII, Fv/Fo, and Fv/Fm at Syferkuil in 2021 with the rhizobium inoculation exhibiting the highest PSII, Kelpak exhibiting the greatest Fv/Fo, and the sole Mycoroot and Mycoroot combined with the rhizobium inoculation exhibiting the strongest Fv/Fm. Among the biofertilizers administered at Thohoyandou, the Kelpak and rhizobium inoculations gave the highest PSII, and the Kelpak sole gave the greatest Fv/Fo. The genotype significantly affected the minimal fluorescence (Fo) in Sikhwahlane in 2019. It was pronounced in accession7 than in accession3 and the genotype affected the Fv/Fm at Syferkuil and was more pronounced in accession7 than in accession3. In 2019’s cropping season, the biofertilizers increased the pod weight and grain yields at Thohoyandou to above-ground biomass and grain yield at Syferkuil, and pod weight to above-ground biomass and the grain yield in Sikhwahlane. In both sites in 2021, the biofertilizers increased the above-ground biomass, harvest index, and grain yield. Accession7 gave the highest value of pod weight at Syferkuil’s cropping season in 2021. The interaction between the biofertilizer and the genotype had no significant effect on the grain yield and yield components in all the locations and in both cropping seasons. Therefore, this makes the biofertilizers an effective tool for increasing the chickpea’s yield in these regions.Item Open Access The effect of chemomutagenesis on root nodulation and seed protein in tepary bean (Phaseolus acutifolius)(2018-05-18) Mashifane, Dipoo Charity; Gwata, E. T.; Bessong, PascalTepary bean (Phaseolus acutifolius) is an important food legume originating from South America and the South-western parts of the United States. The crop is produced in many countries worldwide including South Africa. It is highly tolerant to drought and the seed contains a wide range of vitamins, minerals and protein of high nutritional quality. The genetic base of tepary bean is narrow but can be widened by chemical mutagenesis. However, there are no reports on the impact of chemical mutagenesis on the root nodulation and seed storage proteins in tepary bean. Therefore, this study was designed to examine root nodulation attributes and seed storage proteins of three tepary bean genotypes in the early mutagenic generations (M2 to M4) derived through treatment with varying doses (0.0, 0.5, 1.0, 1.5 and 2.0 v/v) of ethyl methanesulfonate (EMS). The experiment on root nodulation attributes was laid out as a 3 x 5 x 3 (genotypes x EMS doses x mutant generations) factorial design replicated three times. At harvest, shoot height (SHT), primary root length (PRL), dry weights (shoot, root and nodule), number of nodules per plant (NNP) and grain yield components such as the number of pods per plant (NPP) and number of seeds per pod (NSP) were measured. Highly significant (P≤0.01) dose effects were observed for SHT, PRL, shoot dry weight (SDW) and root dry weight (RDW). Highly significant (P≤0.01) interaction effects of mutant generation x genotype x dose were observed for NSP. A highly significant (P≤0.01) positive linear relationship was observed between the NNP and nodule dry weight (NDW). Increase in the PRL suggested that tepary bean mutants could be important in drought tolerance. EMS treatment led to an enhanced partitioning of dry matter (assimilates) to the shoots and roots. There was a three fold increase in most of the root nodulation traits at the 0.5% EMS dose.The Kjeldahl method was used for crude protein determination whereas the sodium dodecyl sulphate – polyacrylamide gel electrophoresis (SDS PAGE) was utilized in determining the protein banding patterns of the bean. There were highly significant (P≤0.01) differences among the genotypes in crude protein accumulation. Highly significant (P≤0.01) mutant generation x genotype x dose were observed for seed protein accumulation. ‘Genotype 3’ attained the highest protein content (24.23%) at 1.5% EMS dose in the M4 generation. EMS doses ≥0.5% positively stimulated protein accumulation in all genotypes but high EMS doses (2.0%) depressed protein content. There were significant variations in seed storage protein profiles among the genotypes and mutant generations. ‘Genotype 6’ showed a distinct 15.0kDa protein fragment which was absent in the majority of the remaining genotypes. The presence of distinct protein subunits in the three genotypes could be used in varietalItem Open Access Effect of genotype and phosphorus fertilizer rates on water use and yield of chickpea(2013-12-09) Madzivhandila, Thendo; Ogola. J. B. O; Odhiambo. J. J. O.;Item Open Access The effect of phosphorus fertilizer and bradyrhizobium innoculation on grain yield and nutrients accumulation in two chickpea (Cicer aritienum L.) genotypes(2020-07) Madzivhandila, Vhulenda; Ogola, J. B. O.; Maseko, S. T.Chickpea (Cicer aritienum L.) is an ancient crop that originated in South-Eastern Turkey and belongs to the genus Cicer, tribe Cicereae, and family Fabaceae. Chickpea has the ability to fix atmospheric nitrogen (N) for its growth. However, chickpea productivity not only depends on N2 fixation or dry matter accumulation, but also the effectiveness of nutrient partitioning to seed, a key component to overall yield. There is a dearth of information on the effect of P with rhizobial inoculation in response of nutrients accumulation in the rhizosphere, shoots and grain of chickpea, especially when determined at different growth stages in the African continent. This study contributes knowledge on this crucial aspect which will likely lead to more other similar research reports in other settings. Therefore, the objectives of this study was to evaluate the effect of P fertilizer rates and rhizobial inoculation on yield and nutrients accumulation in two chickpea genotypes. Field experiments were conducted in winter 2017 and 2018 at University of Venda, Thohoyandou and University of Limpopo’s experiment farm, Syferkuil. Treatments consisted of a factorial combination of two rates of P fertilizer (0 and 90 kg P ha-1), two desi chickpea genotypes (ACC1 and ACC5) and two rhizobial inoculation levels (with and without rhizobiam strain). The treatments were laid out in a randomized complete block design (RCBD) and replicated three times on 22 April 2017 and 11 April 2018 (Syferkuil), 13 April 2017 and 29 April 2018 (Thohoyandou). Macronutrients including P, K, Ca, Mg were determined using the citric acid method. The total N concentration were determined by the micro-Kjeldahl method in both soil, shoots and grain. Zn was extracted using a di-ammonium ethylenediaminetetraacetic acid (EDTA) solution. The content of macronutrients (P, K, Ca, Mg, Ca, and Zn) in soil, shoots and grain was determined by first subjected to wet digestion (Mehlich, 1984). From the digest, various elements were read using relevant procedures. P contents was determined colorimetrically using a spectrophotometer. Yield and yield components were assessed at harvest maturity. Genotypes affected the accumulation of mineral elements in rhizosphere soil, shoots, grain and yield. Accession 5 performed better in most of nutrients elements compared to accession 1 in both seasons and sites. Application of phosphorus alone, and in combination with rhizobium inoculation increased the concentration of majority of nutrients in the rhizosphere. When the test accessions were grown at the Syferkuil and Thohoyandou study location in 2017, they showed significant differences in the concentration of N, P and K while Ca, Mg and Zn were similar in the rhizosphere. The concentrations of N, P and K were markedly higher in the rhizosphere of ACC5 compared to ACC1. In fact, the concentration of P was two-fold greater in the rhizosphere of ACC5 than ACC1. Accession 5 exhibited a markedly higher shoot dry weight, number and dry weight of pods, 100-seed weight, grain yield and harvest index compared to ACC1. P plus rhizobium inoculation, P, rhizobium inoculation affected grain yield and yield components of chickpea genotypes. This preliminary finding show that the combination of P and rhizobium inoculation affected the nutrients accumulation in the rhizosphere, shoots, grain, yield and yield components in both locations. Moreover, Thohoyandou had the highest nutrients accumulation on the rhizosphere, shoots, grain, yield and yield components compared to Syferkuil.Item Open Access Effect of summer and winter rotations on selected soil properties and productivity of succeeding winter chickpea (Cicer arietinum L.)(2020-01) Kgobe, Nnana Magdeline; Ogola, J. B. O.; Odindo, A. O.Chickpea (Cicer arietinum L.) is one of the minor pulse crops in South Africa, but there is hardly any commercial chickpea production in South Africa and the rest of Southern Africa despite its increasing domestic demand. The country meets its domestic demand through imports. Preliminary research has shown the potential of winter sowing of chickpea in rotation with summer crops in the dry environments of Limpopo Province, South Africa. This has provided an opportunity for development of summer and winter crop rotation in the semiarid regions of the Limpopo province, South Africa. There is evidence that crop rotation positively affects physical, chemical and biological properties of the soil consequently increasing the yields in the long run. Therefore, this study assessed the residual effect of summer and winter crop rotations on selected soil chemical properties and soil biological health indicators, and productivity of the succeeding winter chickpea. A field experiment was established during the summer of 2016/17 to determine the effects of summer and winter crop rotations on selected soil chemical properties, biological health indicators, and yield performance at the University of Venda, South Africa. The current study was based on two winter seasons i.e. 2017 and 2018 focusing on chickpea crop. Experimental materials consisted of summer crops [maize (Zea mays), bambara groundnut (Vigna subterranea), cowpea (Vigna unguiculata), mung bean (Vigna radiata)], fallow and winter crops [chickpea - mustard (Brassica rapa)] and combination treatments consisting of summer-winter crop rotations. The field experiments were laid out in a randomized complete block design (RCBD) with three replicates. Seeds were inoculated and sown manually at intra-row spacing of 10 cm and inter-row spacing of 30 cm. Single superphosphate (10.5% P) fertilizer was applied at planting at a recommended rate of 90 kg P ha-1. Supplemental irrigation was applied whenever necessary. Plots were kept weed-free throughout the growing seasons. Soil samples were collected at depths of 0–20, and 20–40 cm prior to planting (experiment I) and after harvesting (experiment II) in 2018. The following chemical properties were determined: soil reaction (pH), cation exchange capacity (CEC), exchangeable bases (M2+, Ca2+, Na+, K+), available P, and (NO3-) nitrate. Soil biological indicators that were analysed include soil active carbon (AC), organic carbon (OC), (NH4+) ammonium and potentially mineralizable nitrogen (PMN). Crop phenology (days to 50% emergence, flowering, and podding) and crop growth (plant height, canopy cover, number of primary and secondary branches) were determined at various crop growth stages. Grain yield and yield components (number of pods per plant, number of seeds per pod and 100 seed weight [100-SW]) were determined at maturity. The data (various agronomic and soil laboratory) obtained were subjected to analyses of variance (ANOVA) using the general linear model (GLM) of Genstat software version 18 to examine the effects of treatments on selected soil properties and crop productivity. Significant differences between treatment means were compared using the standard error of difference (SED) of the means at 5% level. Independent samples t-test was used to compare the differences between experiments and soil depths. Correlation analyses were conducted to assess the relationship between the various parameters measured. Crop rotations did not affect soil pH, CEC, exchangeable cations, P, K and NO3- in both experiment I and II. However, relatively greater soil NO3- and P values were recorded in experiment II compared to experiment I. Similarly, crop rotations had no significant effect on soil AC, OC, NH4+ and PMN in both experiments. Soil organic carbon remained relatively constant across all the soil depths (0-20 cm and 20-40 cm) in experiment I, however, there was an increase in experiment II. There was a statistical difference between experiments on mean soil NH4+, greater mean soil NH4+ values were reported in experiment II in comparison to experiment I. There was no response of crop phenology and growth with respect to crop rotations in both growing seasons (2017 & 2018). However, the crop flowered earlier in 2018 compared to 2017, and the tallest plants were measured in 2017 compared to 2018 growing season. In contrast, 2018 growing season resulted in greater grain yield (1654 kg ha-1) than the 2017 growing season (1319 kg ha-1); for treatments there was no statistical difference found. A similar trend was found with number of pods per plant. There was no significant difference in 100 SW and number of seeds per pod. Based on the current results it can be concluded that crop rotations are generally less effective at improving soil properties and crop productivity in the short term. Many of the chemical and biological attributes of soil quality are stable and their manifestation is experimentally verifiable only over extended periods. Therefore, a study with a more prolonged period would provide useful insight, hence the importance of long-term studies.Item Open Access The effect of various selected shade nets on field-grown bush tea’s physicochemical and antioxidant properties (Athrixia phylicoides DC.)(2023-10-05) Ramenu, Khuthadzo; Mchau, G. R. A.; Ramphinwa, M. L.; Mashau, M. E.Bush tea (Athrixia phylicoides DC.) is an indigenous herbal tea plant in South Africa with medicinal potential. Various parts of this plant are used to make herbal infusions and have been used traditionally for different purposes, including treating other diseases owing to the presence of pharmacologically active metabolites and antioxidants that are believed to be the active ingredient in the plant. However, knowledge of the manipulation of agronomic practice to enhance the accumulation of physicochemical antioxidant properties is not yet present. Therefore, this research was aimed at evaluating the effects of various shade nets colours and light intensities on the physicochemical, polyphenols and antioxidant activities of field grown bush tea leaves. The field experiment was conducted during the 2018 and 2019 autumn seasons at the University of Venda, School of Agriculture. Three replicates of the experiment were conducted using a Randomized Complete Block Design (RCBD) with three distinct degrees of light intensity (i.e., 40%, 50%, and 80%), three shade nets (specifically, black, green, and white) and full sunshine (control, 100%). The individual plots were each 4.8 m x 4.8 m in size. There were 24 plants per plot, with each plot having four plant rows spaced 1.2 m apart and 0.75 m apart within each row. When necessary, a drip watering system was applied to irrigate the plots except during rainy periods. When necessary, weeding was done manually using a hand hoe throughout the cropping seasons. To protect the plants from termites, methamidophos was sprayed at a concentration of 10 mL per 20 L immediately following each weeding session. At the end of the season, the leaves were harvested by cutting the base of the stem and placed inside brown paper bags and stored in the shade at room temperature to allow shade drying process as it is the best method for retaining bioactive compounds and phytochemicals. The leaves were detached from the stems after drying, by the process of threshing and the leaves were ground using the Retsch miller machine. The parameters such as moisture, ash, dry matter, vitamin C, and colour attributes (a*, b*, c*, H° and ΔE) were analysed. In addition, parameters such as chlorophyll content a, chlorophyll content b, total chlorophyll content (TCC), total flavonoid content (TFC), total phenolic content (TPC), as well as antioxidant activities following ABTS and FRAP methods were analysed using a spectrophotometer. For each treatment, the samples were analysed three times. Analysis of variance was conducted in all the collected data using the statistical package SAS version 9.4 statistical software and student’s t-LSDs (Least Significant Differences) were computed at 5%, comparing the means of substantial source effects at a considerable level. The analysis of Pearson's Correlation Coefficient was used to establish the association between the climatic factors and nutritional compositions, polyphenols, antioxidants activities, chlorophyll contents and colour attributes of bush tea. The results revealed that different shade nets colours and light intensities significantly (p <0.0001) influenced the nutritional compositions (moisture, ash, dry matter, vitamin C), polyphenols (TPC and TFC), antioxidants activities (ABTS and FRAP) and physicochemical properties (colour attributes, chlorophyll a, chlorophyll b, and TCC) of field grown bush tea in both years 2018 and 2019. Black shade net colour had a noteworthy influence on total chlorophyll content, chlorophyll a content, and chlorophyll b content. In contrast, green shade net influenced on H° values and the white shade net on TFC. In contrast, the use of shade nets colours had no effects on dry matter (92.86%), vitamin C (3.03 mg AA/100g), or colour attributes [b* (20.65) and c* (20.65)] values of bush tea as they were highly significant at control. The use of 80% light intensity, significantly influences the moisture content, chlorophyll a, chlorophyll b and total chlorophyll content and H°. However, control had a higher influence on dry matter, vitamin C, b*, c* and FRAP results. A very strong, strong, and moderate positive correlation was observed between the climatic factors and nutritional compositions, polyphenols, antioxidants, and chlorophyll contents of field-grown bush tea, under the influence of shade nets colours and light intensities during autumn 2018 and 2019. However, colour attributes: a*, b* and H° resulted in weak/ no correlations. This study is the first to demonstrate different shade nets colours and light intensities as the key factor of accumulating of chlorophyll contents and antioxidants in field-grown bush tea plants. The use of a black shade net together with 80% light intensity resulted in being the best treatment to promote the accumulation of antioxidants compared to other treatments. And it is evident that black shade net together with 80% light intensity was of significant influence after control (100% light intensity). Future studies will be to determine the regulatory effects of shade treatments on the biosynthetic pathway of flavonoids and the accumulation pathways of chlorophyll contents under the shade nets treatment.