EFFECTS OF SEED DISPERSAL UNIT AND THE POSITION OF SEED RELATIVE TO SUBSTRATE ON GERMINATION OF 3 COMPOSITES

Diaspore morphology has long been assigned a role for dispersal by var ious mechanisms. An experiment was designed to investigate the effect of dispersal unit and the position of seed relative to substrate on ge rmination of three composites (Iphonia grantioides, Tridax procumbens and Sonchus arvensis). Seed morphology of the three species was studie d and pappus appeared to influence the overall germination percentage. Diaspore having attached pappus and lying horizontally on the surface of the soil showed maximum germination compared to other positions. D iaspore having detached pappus and lying horizontally on the soil surf ace showed lower germination percentage than the seed with attached pa ppus. The angle of contact with soil is also important besides pappus which presumably regulates water absorption by seed and consequently t he rate and overall germination percentage.