RELATIONSHIP BETWEEN THE DEVELOPMENT OF SEED COAT PIGMENTATION, SEED COAT ADHERENCE TO THE COTYLEDONS AND THE RATE OF IMBIBITION DURING THEMATURATION OF GRAIN LEGUMES

Measurement of the rate of imbibition of individual seeds of dwarf Fre nch beans, chickpea and cowpea at different stages of maturation revea led that cultivars having unpigmented seed coats when mature imbibed r apidly at all stages of maturation, although the overall water uptake was less in the mature seeds. Seeds from cultivars having pigmented se ed coats when mature also imbibed rapidly when harvested at an immatur e stage before the development of pigmentation and when the seed coats were green. However the rate of imbibition decreased markedly in all three species once pigmentation of the seed coat developed during matu ration. The decrease in water uptake of chickpea was attributed to the increased adherence of the seed coat to the cotyledons with little ch ange in seed coat permeability during maturation of the pigmented cult ivar. In cowpea adherence of the seed coal to the cotyledons appeared to play a minor role in reducing the rate of imbibition as the seeds m atured.