Effect of date of sowing on nodulation, growth, thermal requirement and grain yield of kharif mungbean genotypes

A field experiment was carried out during kharif 2005 and 2006 to study the effect of different dates of sowing on nodulation, growth and yield of four mungbean genotypes ‘SML 668’, ‘ML 818’, ‘ML 1265’ and ‘ML 1405’. There was a drastic reduction in yield in case of August 5 sowing in both the years compared to July sowing. Genotype ‘ML 1265’ produced higher yield than ‘SML 668’ in both the years. Interaction between dates of sowing and genotypes for grain yield was significant in 2005. Genotype ‘ML 1265’ produced significantly higher yield than the other genotypes under late sowing of August 5. Early sowing resulted in absorbing sufficient amount of heat units in less time as compared to late sowings which acquired more days to mature during 2006 as compared to 2005 and resulted in accumulation of more growing degree days (GDD) as compared to first season. Among genotypes ‘SML 668’ followed by ‘ML 1265’ consumed lesser days to attain 50% flowering and physiological maturity as compared to other genotypes during both the years. On the basis of two-year mean values, days to 50% flowering were 43.0, 42.0, 41.0 and 39.5 and days to maturity were 70.5, 69.0, 65.5 and 63.0 in July 5, 15, 25 and August 5 sowings, respectively. SML 668 was the earliest in maturity (60.5 days) whereas ‘ML 818’, ‘ML 1265’ and ‘ML 1405’ matured in 69.0, 67.5 and 69.6 days, respectively.