Effects of plant density, nitrogen and phosphorus on black gram (Vigna mungo L. hepper)

The field experiment was conducted in summer seasons of 2007 and 2008 to study the effect of plant densities, nitrogen and phosphorus on black gram. The treatments compared were three plant density (500 × 103,  400 × 103  and 333 × 103  plants /ha), two levels of nitrogen (0 and 20 kg N/ha ) and four levels of phosphorus (0,20,40 and 60kg P2O5 /ha ) were tested in a factorial randomised block design. The growth and yield attributes viz. branches, leaves, dry matter accumulation/plant, pods/ plant, pod length, grains/pod and 1000 grains weight increased with the decrease in plnt density and with the increase in the levels of nitrogen and phosphorus while plant height was positively increased with the increase in plant density and levels of nitrogen and phosphorus. The increase in the seed and straw yield/ha, harvest index and productivity/day/ha significantly increased with the decrease in plant density and increase in the levels of nitrogen and phosphorus. Interaction effect revealed that decreasing plant density and increasing levels of nitrogen and phosphorus increased dry matter accumulation and grain yield significantly. The maximum dry matter (34.4 g/plant) and grain yield (2.07 t/ha) were recored in 333 × 103  plants/ha plant density with 20 kg N and 60 kg P2O5 /ha