Cyst nematode, Heterodera oryzicola, on rice in Kerala I. Estimation of loss in rice due to H. oryzicola infestation, in field conditions Kumari Usha, Kuriyan K. John College of Agriculture, Vellayani. Presented at Nematology Symposium held at Coimbatore, India in February, 1981 Abstract The extent of crop loss caused by cyst nematode, H. oryzicola at different levels of inoculm in rice variety, Triveni, was estimated in a field experiment. It was found that the extent of damage caused to the crop increased with the increase of inoculm levels of 6000, 9000, 12000 and 18000 larvae per sq.m. There was a reduction of 4.39 to 7.65% in the height of the plant, 19.38 to 28.51% in the number of tillers, 10.07 to 28.13% in the number of leaves, 7.36 to 17.10% in the length of ear head, 11.62 to 35.36% in the weight of shoot, 13.76 to 43.37% in the root weight, 7.32 to 28.62% in yield per plot of 1 sq.m. and 7.75 to 36.28% in grain weight per plot of 1 sq.m. over the control. The yield loss per plant was 16.83 to 35.76% and 20.65 to 41.91% in grain weight per plant. There was a correspoilding increase of cyst nematode population and cysts in soil and plant also. The reduction in growth and yield characters of the rice plant was maximum at the highest level of inoculum, showing that the more the nematode population, the more the damage to the plant. Top |