Effect of Heterodera cajani, Rotylenchulus reniformis and Hoplolaimus seinhorsti on pigeonpea biomass.

The effect of Heterodera cajani, Rotylenchulus reniformis, and Hoplolaimus seinhorsti infections on pigeonpea (ICP 2376) biomass was studied under greenhouse conditions (temperature 25–30°C). All the three nematode species significantly (P = 0.05) reduced plant growth. The influence of nematodes on plant growth was visible after 40 days. The relationship between initial nematode density and plant growth retardation was quadratic. H. cajani and H. seinhorsti severely reduced root biomass, while the effect of R. reniformis was more pronounced on shoot weight. Using a quadratic equation, we derived the numbers of H. cajani and H. seinhorsti required to reduce fresh and dry weights of root and shoot by 25 per cent and R. reniformis required to reduce fresh and dry shoot weights by 25 per cent. Most growth attributes were adversely affected (P = 0.05) by 500–1000 nematodes 500 cm−3 soil.