Vol. 8, Issue 1, Part A (2024)

Abstract: An experiment was conducted during Kharif-2019 at Main Rice Research Centre, Navsari Agricultural University, Navsari to studies mechanism of bio-chemical basis of resistance in rice against rice sheath mite, Steneotarsonemus spinki Smiley. At peak stage (100 DAT), the minimum phenol content (4.67±0.10 mg/g) was found in rice variety GR-11 and the maximum phenol content (7.38±0.08 mg/g) was found in variety GR-15. The presence of higher amount of total phenols provided resistance by acting as a barrier to rice sheath mite, S. spinki from utilizing the plant nutrients. It is quite possible that endogenous high levels of phenols rendered resistance against S. spinki. At peak stage (100 DAT), the minimum protein content was recorded 15.40±4.71 mg/100 g in rice variety GR-15 and the maximum protein content was recorded 22.30±6.84 mg/100 g in variety GR-11. Rice varieties, GNR-4, TN-1 and GR-11 with higher protein content evidently supported higher rice sheath mite population. The protein content had been reported to indirectly influence resistance against mite in rice plants. At peak stage (100 DAT), the minimum content of total sugar was recorded 16.65±4.13% in rice variety GR-15 and the maximum content of total sugar was recorded 30.79±4.49% in variety GR-11. The reduction of the total sugar content in rice plant at the critical stages might have adversely affected the rice sheath mite population. At peak stage (100 DAT), the minimum chlorophyll content was recorded 20.71±4.33 (SPAD value) in rice variety GR-15 and the maximum chlorophyll content was recorded 32.92±7.67 (SPAD value) in variety GR-11. The reduction in chlorophyll was less in the rice varieties GR-15, GNR-7 and GNR-3 recording low population of S. spinki.