MORPHOPHYSIOLOGICAL TRAIT PROFILING AND MULTIVARIATE CHARACTERIZATION OF RICE (ORYZA SATIVA L.) GENOTYPES FOR GRAIN YIELD

Abstract

Rice is the largest cereal crop in the world. Increased rice productivity depends on canopy development, physiological traits, photosynthetic activity, phenology, sink formation and assimilate partitioning. A field experiment was conducted at Navsari Agricultural University, Gujarat, India, during the Kharif seasons of 2020 and 2021 to evaluate 20 rice genotypes in a randomized block design with three replications. Various morpho-physiological, phenological and yield related traits were recorded. Pooled means identified IET-28705 as the most consistently superior genotype, recording the highest leaf area (70.13 cm²), leaf area index (0.234), net photosynthetic rate (44.30 µmol CO₂ m⁻² s⁻¹), stomatal conductance (0.446 mol H₂O m⁻² s⁻¹), transpiration rate (5.73 mmol H₂O m⁻² s⁻¹), tiller number (18.93 plant⁻¹), panicle length (30.42 cm), test weight (26.68 g), grain yield (26.63 g plant⁻¹) and harvest index (49.13%). At the genotype level, grain yield showed strong positive correlation with tiller number (r=0.965), LAI (r=0.957), leaf area (r=0.956), photosynthetic rate (r=0.952), stomatal conductance (r=0.929), transpiration rate (r=0.922) and panicle length (r=0.854). A parsimonious three-predictor regression model explained 94.6% of the variation in pooled grain yield (R²=0.946; adjusted R²=0.936); path analysis identified tiller number as the largest direct contributor (0.844), followed by harvest index (0.157). The hierarchical clustering separated the genotypes into four phenotypic groups, with IET-28705, IET 28701, IET-28696 and IET-28704 forming a high-performance cluster. These integrated results support the use of canopy, gas-exchange and sink traits for better genotype identification.