The effect of water stress on the germination of Citrullus lanatus seeds

The germination of Citrullus lanatus seeds is extremely sensitive to water stress. A decrease of 13,6 % in the total water content is sufficient for the complete inhibition of germination. Exposure of seeds to water stress at a very late stage of germination after normal incubation in water prevents radicle emergence. Prolonged water stress treatment does not induce secondary dormancy in these seeds. Water stress which completely inhibits germination does not appear to affect the conversion of phytochrome intermediates to Pfr or the photoreversibility of phytochrome during light treatments

A preliminary study on the germination of Sclerocarya birrea subsp. caffra

Seeds of Sclerocarya birrea (A. Rich.) Hochst. subsp. caffra (Sond.) Kokwaro, commonly known as marula, occur in locules within a hard lignified endocarp. The endocarp appears to restrict germination mainly by offering mechanical resistance. It may also restrict the leaching of germination inhibitors and possibly serve as a barrier to oxygen diffusion. The endocarp does not restrict water uptake. High germination counts were only obtained by removing opercula. Leaching slightly improved germination of seeds in intact endocarps. The optimum germination temperature of opercula-removed seeds was between 27° and 37°C. Storage improved rate of germination