Phenotypic Variation Characterization and Multiple-Method Analysis of Drought Resistance in Rice at the Germination...

Drought stress is a major abiotic factor limiting rice growth and productivity. Developing scientifically screened methods at the germination stage is critical for identifying superior drought-adapted genotypes. This study aimed to develop a novel discriminant equation for evaluating germination-stage drought resistance in rice, using field yield data as a benchmark to calibrate laboratory assessments. Seventy-six rice accessions from southern China were used as experimental materials. Drought resistance during germination was assessed using nine key phenotypic indicators. Three statistical methods-membership function synthetic value (MFSV), principal component analysis synthetic value (PCASV), and grading coefficient (GC)-were applied to classify drought resistance levels from different analytical perspectives. Field drought treatment was conducted throughout the growth period, and final grain yield was used to represent the comprehensive drought resistance (CDR)of each accession. Results showed only 45% of the accessions were consistently classified by all three statistical methods, indicating that the choice of analytical approach influences the outcome. In addition, MFSV, PCASV, and GC were all positively correlated with CDR, supporting the use of CDR as a reliable reference for integrating laboratory-based evaluations. Finally, a Fisher discriminant function was established using MFSV, PCASV, and GC as independent variables (X) and CDR as the dependent variable (Y), providing a more comprehensive and scientifically robust method for assessing drought resistance at the germination stage.