Seed Germination and Seedling Establishment of Securidaca Longerpedunculata (Polygalaceae)

Abstract

Securidaca longepedunculata Fresen. (Polygalaceae) is a multipurpose tree valued for its medicinal uses in Limpopo Province, South Africa. Hence, it is threatened due to human pressure which affects its regeneration potential since it is uncultivated. This poses a challenge in efforts aimed at its conservation. The objective of the present study was to investigate the germination potential of Securidaca longepedunculata seeds which have a very low and erratic germination under natural conditions. Seeds were collected in Nylsvley Nature Reserve and a number of pre-treatments, namely seed coat removal, sulfuric acid, gibberellic acid, boiled water, cold water and control were tested for their efficiency to improve germination under field, laboratory and greenhouse conditions. The results showed that some of pre-treatments have a stimulating effects on seed germination and seedling growth. Removal of the seed coat resulted in the highest germination percentage. This pre-treatment gave 90% seed germination under greenhouse conditions, while it was 63.3% for those grown in the laboratory, whereas untreated seeds under field conditions showed 0% germination. Boiled and cold water pre-treatments did not improve seed germination. The average heights of seedlings from different pre-treatments ranged from 4.5 cm to 22 cm with the highest seedling (22 cm) obtained in seed pre-treated with 400mg/l of gibberellic acid. It is concluded that removal of the seed coat is the most effective pre-treatment