Assessing Different Rice Genotypes Tolerance against the Major Pests and Identifying the Biochemical Basis of Tolerance

Abstract

A total of 196 rice genotypes were screened for tolerance against paddy stem borer and leaf folder pests under open field conditions. Damage assessment followed the standard evaluation procedure for rice developed by IRRI (1988). Stem borer incidence was recorded during both the vegetative and reproductive stages while leaf folder incidence was recorded at five different growth stages (30, 40, 50, 60, and 70 days after transplanting). Interestingly, tolerance to paddy stem borer varied among the genotypes. Genotypes resistant at the Vegetative Stage did not show tolerance at the Reproductive Stage. Consequently, leaf folder infestation was recorded at five different growth stages, demonstrating that although the mean infestation was considered for identifying tolerance, the rate of infestation against an accession is not consistent across all growth stages. Additionally, biochemical analysis of the resistant entries, along with a susceptible check (TN1), revealed that higher total phenol concentrations, moderate chlorophyll content, and lower sugar levels were key factors contributing to pest tolerance. The correlation between infestation percentage and biochemical parameters showed a high positive correlation between total sugars and infestation percentage and a strong negative correlation between total phenols and infestation percentage, indicating that phenols play a role in plant defense.