Department of Plant and Soil Sciences

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Open Access
Simulating the effects of nitrogen and phosphorus on the growth and yield of maize in Vhembe District, Limpopo Province
(2013-02-25) Makhaga, Ngeletshedzo Superior; Odhlambo, J. J. O.
Maize is the main staple food in South Africa and its production in the country constitute 50 percent of the output in Southern African Development Community (SADC) region. This study was conducted to determine the effect of nitrogen (N) and phosphorus (P) on maize growth and yield and to use the data collected in Agricultural Production Systems Simulator (APSIM) to predict the response of maize toN andP applications as observed in the field. The study was conducted over two seasons, 2005/2006 and 2006/2007. The study evaluated the biomass production, grain yield, plant tissue N and p content and soil N andp content during maize growth. The APSIM model was used to predict biomass and maize yield. Treatments consisted of N ferlilizer application at O and 75 Kg/ha in 2005/2006 season and o, 37.5 and 75 Kg/ha in 2006/2007 season as Limestone Ammonium Nitrate (LAN). Phosphorus was applied at O and 30 Kg/ha as Single Super Phosphate (SSP) at planting in both seasons. Maize (Zea mays L) was the test crop and was planted at a spacing of 90 x 25 cm. Individual plot sizes measured 5mx 4.5m and were laid out in Randomized Complete Block Design with three replications. Biomass was collected at three stages of maize growth, 6-8 weeks after planting, tasseling and at harvest. At maturity, grain was harvested and the yield was determined. Analysis of the variance (ANOVA) using the Gener.al Linear Model procedure (GLM) was used to assess the variation of biomass production, grain yield and plant tissue N and P content among treatments. Chi-square test was used to assess the differences between the observed and the predicted biomass and grain yield. The predicted Pearson correlation was used to determine the relationship between soil N at different stages of maize growth and the plant tissue N content and again between soil P at different stages of plant growth and plant tissue p content. There was a significant (P<0.05) difference in maize biomass among plots treated with N and those without N at 6-8 weeks at Univen in both seasons. There was no significant (P<0.05) biomass amongst all treatments at tasseling and at harvest at both sites and seasons. There was no significant (P<0.05) difference in maize grain yield amongst the treatment plots at both sites and seasons. There was no interaction between N and P in biomass and grain yield at both sites and seasons. There was no significant (P<0.05) difference in plant tissue N and P among the treatments. Plant tissue N was not correlated to soil N at all stages of growth. Plant tissue P was strongly correlated to soil P at different stages of maize growth. The predicted grain yield and biomass yield using APSIM were higher than the observed yield in most treatments. There was a strong relationship between the observed and the predicted biomass yield at 6-8 weeks (r2=0.940) and at tasseling (r2=0.919) at Univen site in 2005/6season. There was an agreement between the observed and predicted grain yield at Univen in both seasons (r2= 0.654 and r2= 0.755). The chi-square results showeda significant difference between the observed and the predicted biomass and grain yield. Therefore, for APSIM to estimate more acceptable results, the environmental management window should be incorporated.
Open Access
Spatial variability of soil and land suitability evaluation for specific crop ranges for Rambuda Irrigation Scheme in Vhembe district
(2013-09-18) Nethononda, Lutendo Obert; Odhiambo, J. J. O.; Peterson, D. G.
Rambuda Irrigation Scheme is a 120 hectare communal irrigation scheme established in 1952. There is no information on soil or basis for crop choices, consequently tamers have been growing crops on trial and error basis using local knowledge of soil and empirical observations of crop performance under various soil and climatic conditions. Such information is insufficient to make appropriate land use decisions. The objective of this study was to investigate the spatial variability of soil at Rambu
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.
Production of chickpea in South Africa is currently insignificant but local demand is high. There are no recommendations on suitable genotypes of chickpea and agronomic practices at present. This study aimed at evaluating the effect of genotype and phosphorus (P) fertilizer rates on water use and yield of four chickpea genotypes. A field experiment was undertaken, in winter 2009 and summer 2010, using a factorial arrangement of 3 P fertilizer rates (0, 45 and 90 kg P ha-1) and 4 chickpea genotypes (ICCV92944, ICCV3110, ICCV4306 and ICCV7307) laid in a randomized complete block design and replicated 3 times. Total crop biomass was determined at vegetative, 50% flowering, and harvest maturity (HM) stages and number of pods per plant, seeds per pod, 100 seed weight, grain yield and harvest index (HI) were determined at harvest maturity. Water use (ET) was determined by measuring soil moisture content at week intervals. eutron probe was used to measure soil moisture content every week after emergence until physiological maturity. Soil moisture value was used to determine crop water use. Water use efficiency was determined as the ratio of crop biomass or grain yield to water use (ET). Genotype and P fertilizer rates affected the crop biomass at vegetative and 50% flowering stage in season I and season II. Desi genotypes had greater crop biomass compared with kabuli genotypes in winter and summer season. Genotype did not affect crop biomass at harvest maturity in both winter and summer season but the application of phosphorus fertilizer rate significantly (P<0.01) affected crop biomass at harvest maturity in 1'. summer season. Genotype significantly affected grain yield in winter (P<0.05) and summer (P<0.01) se·ason. The desi types significantly had greater grain yield ( 1464 and 979 kg ha-1) compared with kabuli types (680 and 274 kg ha-1) in season I. In contrast, the kabuli types significantly had greater grain yield (1538 and 1396 kg ha-1) compared with desi types (1196 and 983 kg ha-I) in season II. Application of phosphorus fertilizer rates did not affect grain yield in season I probably due to water deficits in winter season. In contrast, P fertilizer application rates significantly (P<0.01) affected grain yield in season II.Phosphorus fertilizer at the rate of 90 kg P ha-1 produced significantly greater grain yield (1585.0 kg ha-I) followed by 45 kg P ha-I (1313.0 kg ha-1 and 0 kg P ha-1 (935.0 kg ha-1 in season II. Genotype and did not affect water use (ET) in season I (average 221.3 mm) and season II (average 314.2 mm). Phosphorus application also did not affect water use (ET) in season I (average 221.3 mm) and season II (average 314.2 mm). The desi types significantly had greater water use efficiency of grain yield (WUEg) (6.36 and 4.41 kg ha-1 mm-1) compared with kabuli types (2.69 and 1.33 kg ha-1 mm- 1) in season I. In contrast, the kabuli types significantly had greater water use efficiency of grain yield (WUEg) (4.90 and 4.40 kg ha-I mm-1) compared with desi types (3.41 and 3.12 kg ha-1 mm-I) in season II. Application of phosphorus fertilizer rates significantly (P<0.05) affected water use efficiency of grain yield (WUEg) in season I and season II. Application of phosphorus fertilizer at the rate of 90 kg p ha-I produced significantly greater water use efficiency of grain yield (WUEg) compared with 45, 0 kg P ha-1 Therefore desi genotypes may be more favourable in winter season. In contrast, kabuli appears to be more suitable in summer season while 45 and 90 kg P ha-1 phosphorus fertilizer rates may increase chickpea yield for the site of current study in both season and season II.
Open Access
Performance of selected different types of stone fruits in a summer rainfall area, South Africa
(2013-12-10) Ramphinwa, Maanea Lonia; Mchau, G.R.A.; Gwata, E.
Temperate fruit trees cultivated in areas of mild winter conditions result in a number of insufficient chilling symptoms. Such insufficient symptoms are described in general as the absence of bud break, delayed foliation, reduced fruit set as well as reduced fruit quality. Therefore, after bud break, fruit trees show insufficient symptoms such as paralysis of the shoot growth, development of small leaves, low rate of effective fructification, and reduction of the flowering-maturity circle and development of small flat fruits. Adequate information of chilling requirements, dates of dormancy breaking and appropriate chemical agents, which should be applied to meet chilling requirement is required for successful production of stone fruit. South African (SA) deciduous fruit has been exported successfully (primarily to the UK and Europe) since 1892 and SA is currently a major Southern Hemisphere supplier of fresh fruit between the months of October and August (Huysane, 1996). In order to remain competitive, there is a need to expand the production of stone fruits from traditional Western Cape to a summer rainfall area in Limpopo Province. The broad objectives of the study was to evaluate some quantitative and qualitative performance traits of different types of stone fruits in a summer rainfall area in Limpopo Province. The project was initiated in 2007 by Agricultural Research Council through the collaboration of Agricultural Research Council (ARC) Infruitec-Nietvoorbij (Stellenbosch) Western Cape and University of Venda in Limpopo Province. This was a continuous assessment about the performance of selected stone fruit cultivars in a summer rainfall area, South Africa. Growth data was sampled on each tree. Circumference measurement of the graft union after the growing season was measured using a soft pliable measuring tape in order to get an indication of the growth rate. This was done annually during winter period. The experimental design was a completely randomized design (CRD) with six trees (experimental units) randomly selected for each of the four species ('Charisma', 'Summersun', 'Pioneer 'and 'Mayglo'). Analysis of variance was performed on all variables accessed using GLM (General Linear Models) Procedure of SAS statistical software version 9.2 (SAS Institute Inc., Cary, NC, USA, 2003). Shapiro-Wilk test was performed to test for normality (Shapiro, 1965). There was significant different on diameter of stems, scion height and production of secondary branches of trees on the four different stone fruit trees studied. 'Mayglo' and 'Summersun' trees had high buds production, blooming, and fruit-set than 'Charisma' and 'Pioneer' trees in year 2009. All trees had a very good bud production and blooming, but only 'Mayglo' and 'Summersun' had a good fruit set compared 'Charisma' and 'Pioneer' in year 2010.
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 below
Open Access
Organic manure effects on selected soil properties, water use efficiency and grain yield of sunflower
(2016) Mokgolo, Matome Josphinos; Mzezewa, J.; Odhiambo, J. J. O.
The application of organic manures as alternatives to reduce the use of mineral fertilizers is considered a good agricultural practice for smallholder farmers. However, the effect of organic manure on soil properties and crop yield depends upon its application rate and chemical composition. Climatic seasonal variability within the study area could adversely affect crop production. The amount of rainfall and temperature are among the most important factors that determines crop production. This field experiment was carried out during the 2013/2014 and 2014/2015 cropping seasons at the University of Venda experimental farm which is located about 2 km west of Thohoyandou town in the Vhembe District, Limpopo Province. The main objective of this study was to determine the effect of three types of organic manure (cattle, poultry and their combination (1:1)) on yield and water use efficiency of sunflower (Helianthus annuus L.) and selected soil physical and chemical properties under rainfed conditions. The experiment was a randomized complete block design (RCBD) with four treatments and four replications (control (C0), cattle manure (CM), poultry manure (PM) and their combination (CM + PM)). All organic manures were applied 21 days before planting at a rate equivalent to 20 t ha-1. The manures were incorporated in the soil using a hoe to an approximate depth of 10 cm. Crop water use (WU) and water use efficiency (WUE) were determined using the water balance equation. Rainfall was measured using three standard rain gauges installed on the experimental site. Change in soil moisture storage was determined by monitoring soil moisture content weekly using a neutron water meter (NWM), calibrated on the experimental site. Data on sunflower dry matter and leaf area index (LAI) was collected at flower bud stage, flowering stage and at grain maturity stage. Plant height and stem girth were also determined at the same developmental stages. Grain yield was measured at physiological maturity. Analysis of variance (ANOVA) was carried out using SPSS software. Due to seasonal variability encountered during the two cropping seasons, particularly in terms of rainfall, further analysis of two factors (viz. cropping season and organic manure) and their interaction were performed. The differences between treatment means were separated using the least significant differences (LSD) procedure. The results showed that organic manure application had no significant effect on soil physical properties. Poultry manure application resulted in lowest bulk density (BD) with a decrease of 32% in the top layer (0 – 20 cm) compared to control. Cattle manure + PM and CM application decreased BD in the top layer by 14% and 9% compared to control, respectively. Poultry manure and CM recorded almost the highest similar stable aggregate fractions at all soil depths. Poultry manure recorded the highest final infiltration rate and cumulative infiltration followed by CM and CM + PM. The control treatment retained the highest mean water content compared to other treatments at both field capacity (FC) and wilting point (WP). Cattle manure + PM and PM recorded the least mean water content among others at FC and WP respectively. This could be as a result of increased micropores by organic manure application on a clayey soil which allowed an ease movement of water that control treatment which had no manure application. Total N, Ca, and Zn were significantly different between treatments in the first cropping season while K, Na, CEC and Zn were significantly different in second cropping season. pH recorded no significant difference in all treatments in both cropping seasons. CM + PM recorded the highest OC at top layer (0 – 20 cm) in both cropping seasons compared to other treatments. Dry matter yield and LAI at flower bud, flowering and maturity stages increased with the application of different manures compared to the C0. Organic manure application showed a significant (p<0.05) effect on dry matter at all growth stages in the second cropping season. Organic manure had a significant effect on LAI only at flower bud stage of the first cropping season, with PM and CM + PM recording the highest similar value of 1.31. The manure application also showed a significant (P<0.05) effect on plant height and stem girth at all growing stages in the second cropping season, whereas in the first cropping season the significant effect was only in the flower bud stage for both parameters. Grain yield was significantly affected by the manure application in the second cropping season. Manure application in the second cropping season resulted in an increase in the grain yield compared to the first cropping season, except for PM where the grain yield decreased significantly by 167.92% from the first cropping season. Then high grain yield in the second cropping season could be as a result of high WUE reported. The manure application had a significant effect (p<0.05) on water use efficiency (WUE) in the second cropping season. The WUE recorded the highest values under CM and CM + PM treatments in second cropping season than in first cropping season, while PM recorded the highest WUE value in the first cropping season. Generally, organic manures used obtained higher grain yield and WUE compared to control.
Open Access
Effectiveness of indigenous tree species (Spirostachys africana) extracts against Sitophilus Zeamais (Mostschulsky)
(2016-02-11) Ndou, Zwivhuya Leonard; Kunjeku E.C.; Mojapelo P.E.L.
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.
Open Access
The Response of Tepary Bean (Phaseolus actifolius) Germplasm to Induced Mutation
(2016-05) Thangwana, Andries; Gwata, E. T.; Zhou, M.
See the attached abstract below
Open Access
Survey of diseases on Marula (Sclerocarya birrea), in Tshikundamalema, Limpopo Province, South Africa
(2016-05) Ramabulana, Elelwani; Kunjeku, E. C.; Roux, J.; Coetzee, M. P. A.; Coutinho, T. A.
See the attached abstract below
Open Access
Genetic Study of Pod Shattering Resistance in Soybean (Glycine max (L.) Merrill) Plant Populations Derived from Exotic x Local Germplasm
(2016-05) Nevhudzholi, Khuliso Marine; Gwata, E. T.; Mchau, G. R. A.
See the attached abstract below
Open Access
Morpho-physiological characterisation of bambara groundnut (Vigna subterranea L) landraces collected in Mpumalanga Province
(2016-09) Magongwa, Selwana Michael; Ogola, J. B. O.; Mathews, C.
See the attached abstract below
Open Access
The effects of relative planting dates of legumes on productivity of cassava - legume intercrop
(2017-08-18) Legodi, Khutso Debra; Ogola, J. B. O.; Gwata, E. T.
See the attached abstract below
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.
Open Access
Regeneration potential of selected medicinal plants used to treat human and livestock diseases in Limpopo Province of South Africa
(2018-05-16) Ojelade, Babatube Solomon; Ogola, J. B. O.; Mwihomeke, S. T.
Many high valued tree species of medicinal significance in the Limpopo Province, South Africa exhibit seed dormancy, and also contain aromatic oils which inhibit rooting of their stem cuttings. These plant species are under pressure due to human over-exploitation. The main objective of this study was to investigate effects of rooting hormones on the rooting ability that will help in domesticating some of the selected high valued medicinal plants, Elaeodendron transvaalense (bushveld saffron), Brackenridgea zanguebarica (yellow peeling plane), and Warburgia salutaris (pepper-bark tree). Stem cuttings of these plant species were prepared and treated with various concentrations (500, 1000 and 2000 ppm) of IBA, IAA and NAA in different growth media (Natural soil, farm soil and hygromix) at a nursery house. 180 experimental units were sown and arranged in Randomized Complete Block Design (RCBD), each treatment replicated five times and then monitored for a period of three months. Data were only obtained from Brackenridgea zanguebarica as other species dried up two weeks after sprouting. The two variables measured from the experiments were sprouted stems and number of leaves. The data obtained were subjected to analysis of variance and least significant difference (LSD) at 5% probability level was used to compare treatment using STATISTICA software analysis package. The hormone, hormone concentration, growth media and their interactions had effect on sprouted stems and number of leaves produced on Brackenridgea zanguebarica cuttings, with no record of rooting ability. IBA (500 ppm and 1000 ppm) and control (without rooting hormone) showed high significant results with natural soil and farm soil in terms of leaf production compared to the hygromix, which is significantly lower from others. IBA at the various concentrations (500, 1000 and 2000 ppm) and the control gave the highest percentage sprouted stem on both natural soil and farm soil as compared with other hormones at the same
Open Access
The effect of water stress and storage conditions on seed quality of chickpea genotypes characterized by differences in seed size and coat colour
(2018-05-18) Vilakazi, Busisiwe; Ogola, J. B. O.; Odindo, A. O.
Chickpea (Cicer arietinum L.) is an excellent utilizer of residual soil moisture in agricultural ecosystems. However, its seed quality and hence reproduction is constrained by water stress, seed size and storage conditions. This study was carried out at the University of KwaZulu- Natal (UKZN), Pietermaritzburg Campus. It was conducted to evaluate the performance of chickpea genotypes (Desi-K, Saina-K and ICCV-K) with different seed sizes on seedling emergence (i), seed ageing effect on seed quality and imbibition of genotypes produced under water stressed and non-stressed conditions (ii), and (iii) the effect of water stress during seed development on sugars and protein accumulation, germination and seed vigour. Pot experiments were conducted under glasshouse / tunnel conditions at the Controlled Environment Facilities (CEF). The experiment for objective 1 was laid out as a single factor in completely randomized design (CRD). Data on emergence rate, final hypocotyl and complete emergence was collected. The small seeded Desi-K showed higher and faster emergence compared to medium sized Saina-K and large seeded ICCV-K. In the experiment of the second objective, seeds of the three genotypes were first obtained by production under water stressed and non-stressed growing conditions. They were then aged for 0, 1, 3, 5, or 7 days at 41 ºC and 100% relative humidity to form a 2 x 3 x 5 (water levels x genotypes x ageing) factorial design. Data was collected on germination percentage (GP), mean germination time (MGT), electrical conductivity (EC), tetrazolium chloride test (TZ) and imbibition weight. Seed ageing caused progressive loss of seed viability and vigour in all genotypes, which resulted in lower GP, delayed MGT, reduced TZ staining, cell death and high solute leakage from the seeds produced under the two water regimes. However, the effect was more severe under water stressed conditions. In the experiment for objective 3, seeds of all three genotypes were larger when grown under non-stressed condition compared to those under water stressed condition. These larger seeds had higher seed viability and germination percentage but lower electrical conductivity and mean germination time. Stressed seeds had higher soluble sugars than non-stressed seeds. It was deduced that irrigation during seed development reduces the final sugars and protein content but increases the seed size and physiological quality parameters allied to production of chickpea. Therefore, water provision to chickpea crop is critical during seed development.
Open Access
Evaluation of Diverse Cowpea (Vigna unguiculata [L.] Walp.) Germplasm for Field Performance and Drought Tolerance
(2018-05-18) Nkoana, K. D.; Gwata, E. T.; Gerrano, A. S.
Open Access
Multi-Location Field Evaluation of Bambara Groundnut (Vigna Subterranean (L) Verdc) for Agronomic Performance and Seed Protein.
(2018-05-18) Mogale, Tlou Elizabeth; Gwata, E. T.; Zhou, M.
Bambara groundnut (Vigna subterranea) is one of the most important legumes cultivated primarily for food by smallholder farmers in Africa. It is an affordable source of protein and contributes to income generation as well as soil fertility. Despite its importance, it is cultivated largely for subsistence purposes in South Africa. Growers use landraces. The agronomic performance of the traditional varieties depends on environmental factors prevailing in a particular area. In Limpopo and Mpumalanga Provinces, there is no adequate information regarding the performance of bambara groundnut germplasm. The objectives of the study were to (i) determine the agronomic performance of Bambara groundnut across three contrasting locations in Limpopo and Mpumalanga provinces over two cropping seasons (ii) determine the genotypic variation in the seed protein level among 42 bambara groundnut genotypes. Forty-two bambara groundnut genotypes were evaluated under three different environmental conditions (Syferkuil, Thohoyandou and Nelspruit) over two (2013/2014, 2014/2015) seasons in a 7 × 6 rectangular lattice design replicated three times. Eight agronomic traits including dry shoot weight (DSW), number of pods per plant (NPP), pod length (PL), number of seed per pod (NSP), pod weight per plant (PWT), seed weight per plant (SWT), 100 seed weight (100-SWT) and seed yield (SYLD) were measured. The results showed that there were significant genotype x location interactions which demonstrated that the prevailing agro-ecological conditions at the test locations were distinct from each other. Five genotypes (‘BGN-19‘, ‘BGN-11‘, ‘BGN-12‘, ‘BGN-4‘and ‘BGN-34‘) attained >25.0% seed yield advantage over the local check ‘BGN-39‘. The results also showed that light brown coloured genotypes attained relatively higher seed yield compared to the other seed colours types. The cultivar superiority index (CSI) showed that three genotypes (‘BGN-12‘, ‘BGN-19’ and ‘BGN-34’) were the most stable across the test locations and attained >900.0 kg/ha on average. There were significantly high positive correlations between PWT and each of the three other attributes (SWT, 100 SWT and SYLD). In terms of seed protein, the results showed a poor relationship between seed yield and protein levels. ‘BGN-12’ which produced the highest seed yield, attained the lowest percent seed protein while genotype. On average, the genotypes contained 21.72% protein. The highest and lowest seed protein quantities were attained by the genotypes ‘BGN-42’ (25.17%) and ‘BGN-12’ (19.89%) respectively.
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.
Open Access
The effectiveness of Solanum panduriforme (Mey) based extracts on the cabbage aphid, Brevicoryne brassicae (Linnacus) on brassicas
(2018-05-18) Mhazo, Mary Louis; Kunjeku, E. C.; Addo-Bediako, A.; Blair, B.
Brassicas are important vegetable crops grown for home consumption and market gardening in eastern and southern Africa. However, productivity is affected by aphids, through both direct feeding and disease transmission. Botanical insecticides have potential to control the aphids, but so far few plants have been evaluated for use on brassicas. This study was conducted to evaluate the effectiveness of Solanum panduriforme to control aphids on brassicas. Botanical extracts from three parts of S. panduriforme were assessed for their insecticidal effects on the cabbage aphid, Brevicoryne brassicae. The extracts from leaf powder (LP), ripe berry powder (BP), fresh ripe berries (RB) and fresh unripe berries (UB) were extracted with four solvents; water, ethanol, hexane and diethyl ether, using homogenisation, maceration and solvent-assisted / sequential extraction methods. The effectiveness of the extracts was determined by laboratory bioassays as well as by plant assays in the screen house and under field conditions. The experiments were replicated three or four times depending on the assays and the design used was completely randomized design (CRD). The immature (LP and UB) plant parts were generally more effective than the mature (BP and RB) plant parts, with mortalities ranging from 100 % down to 40 % respectively depending on assays. Ethanol extracts were more effective than aqueous extracts (LP 96% and 63%; BP 96% and 64%; RB 100% and 64%; UB 100% and 90%). The dried crude extracts from hexane were more effective than di-ethyl ether extracts. The group chemical analysis indicated presence of alkaloids in the berries (BP, RB and UB), which were absent in the leaves (LP). Phenolic compounds and flavonoids were present in all the extracts (LP, BP, RB, and UB). Saponins were present in the fresh parts (RB and UB). The results show how the locally available S. panduriforme plants can be used as an aphicide to control aphids on brassicas. Farmers can directly prepare an easy and cheap botanical