Studies on Nutrient Status in Rice Foliage and its Relationship with Leaf Folder and Brown Planthopper Incidence

The biochemical analysis of rice foliage at 75 days after transplanting (DAT) during Kharif 2003 revealed that the susceptible cv. Jaya retained higher amount of N and P (1.771 and 0.267%) in foliage, while the moderately resistant cv. Surendra at the same age retained more K and Zn (1.397% and 112.877 ppm) irrespective of nutrient levels tested. Combined application of ZnSO₄and NPK fertilizers (F₃and F₄) enhanced the N, K, Zn and sulphur content in the foliage as compared to application of only NPK fertilizers (F₁and F₂). However, the phosphorus content of foliage was high in F₁and F than that of F and F₄, respectively. Zinc and sulphur uptake in foliage also increased when NPK dose was increased. Application of triazophos resulted in reduction of N and P contents and increase of K and Zn in rice foliage regardless of cultivars and nutrient levels. Increase in N (r = 0.7390**) and P (r=0.6279**) contents in the foliage also showed a significant positive correlation with brown plant hopper (BPH), while the nitrogen content in foliage was positively correlated with leaf folder (LF) incidence only (r = 0.7427**). The K content in foliage showed negative relationship with BPH and LF incidence, while Zn and sulphur content were found negatively related with BPH only. On the contrary, there was positive correlation between Zn and sulphur contents and LF incidence.