Symbiotic efficiency, thermal requirement and yield of blackgram (Vigna mungo) genotypes as influenced by sowing time

Abstract

A field investigation was carried out during summer 2008, 2009 and 2010 at Research Farm of Punjab Agricultural University, Ludhiana, to study the performance of spring blackgram [Vigna mungo (L.) Hepper] genotypes (Sekhar 2, Pant U 19, Pant U 31, WBU 109, Mash 364 and Mash 1008) on different dates of sowing (10 March, 15 March, 20 March and 25 March). The grain yield recorded in 20 March sowing was significantly higher than the other sowing dates. Blackgram sown on 20 March registered 17.2, 3.2 and 4.5% higher grain yield over 10, 15 and 25 March sowing dates, respectively. Number of nodules was not significantly influenced by sowing dates. Nodule dry weight was significantly higher in 15, 20 and 25 March sowings than 10 March sowing. Early sown crop took more number of days to 50% flowering and maturity than late sown crop in 2008 but these were increased with delay in sowing in 2009 and 2010. Early sown crop required lower agroclimatic indices, i.e. growing degree days, heliothermal units, photothermal units than the late sown crop. Among genotypes, Mash 364 yielded the highest (1 136 kg/ha), closely followed by Mash 1008 (1 125 kg/ ha), both being significantly superior to all other genotypes. The optimum time of sowing for spring blackgram was found to be 15-25 March and Mash 364 and Mash 1008 were the promising genotypes.