HARD SEED STUDIES IN BLACK GRAM (VIGNA-MUNGO L)

The effect of environment on hard seeds, release of dormancy and methods for breaking hard seeds were studied in black gram. Impermeability to water is the major cause of hard seeds (dormancy) in food legume crops. Environment also affects the development of hard seeds. Sixty five genotypes of hardbean were evaluated for their hard seededness during Kharif 1985 and Summer 1986. The formation of hard seeds was higher in Kharif sown crop as compared to summer sown crop. This might be due to low temperature and high humidity in the environment during the time of seed maturation. Fifty percent hard seeds were observed 15 days after harvest maturity which decreased with later harvests. The percentage hard seededness declined to a very low level four months after initial harvest maturity. The percentage of hard seeds ranged from 10% (UH83-14) to 76% (UH-83-6) in the genotypes grown during Kharif 1986; whereas, in the summer crop, hard seed varied from 0% to 15% (UH83-12), (UH83-13), (UH80-9),(UH-83), (UH-22) and (UH84-4), respectively. Eleven genotypes were selected for having the maximum number of hard seeds. Different methods for breaking hardseededness such as scarification with sand paper, concentrated H2SO4 treatment for 30, 60 and 120 seconds, and hot water treatment at 80-degrees-C for two minutes were used. Treatments with H2SO4 for 60 and 120 seconds and scarification with sand paper gave 86%, 86% and 80% germination, respectively. Germination for the control was only 28%.