Impact of nitrogen and silicon amendments on hopper population in rice

Present study showed that total dry weight values of rice plants were significantly higher in the plant with high nitrogen (N) application (100kg/ ha) as compared to low nitrogen (30 kg/ ha) treatment whereas the silicon (Si) amendment had very little effect on biomass accumulation but both the elements are associated with hopper pest population densities in rice. Here the correlation coefficient values were high- r= 0.759 to 0.999 and r= 0.726 to 0.996 for brown planthopper Nilaparvata lugens (Stål) and green leafhopper Nephotettix virescens (Dist.) respectively when the calculation was made between insect population and plant biomass after application of nitrogen 0 to 100 kg/ ha. However, when calcium silicate was added 140 kg/ ha or above with high doses of nitrogen the N. lugens and N. virescens incidence reduced in comparison to others. Consequently, the interaction between nitrogen and silicon play a significant role in resistance to these hopper pests.