A novel method for evaluating rice black‐streaked dwarf virus disease severity based on plant dwarfing index

Abstract Rice black‐streaked dwarf virus disease (RBSDVD) poses a severe threat to rice production in China. Currently, the resistance levels of rice varieties to this disease are evaluated based on the incidence rate, which is a singular criterion that fails to capture the nuanced differences among cultivars with similar resistance levels. This study reveals a positive correlation between the severity of RBSDVD and the degree of plant dwarfing. We propose a refined evaluation method using the plant dwarfing index (PDI) to assess the resistance of different rice varieties. By analyzing the incidence rates and PDIs of four rice varieties with varying resistance levels after inoculation, we found that the PDI more accurately reflects the differences in disease severity among the varieties compared to the incidence rate. This PDI‐based method for evaluating RBSDVD severity provides a scientific quantitative tool for future rice breeding and resistance mechanism studies.