Correlation and principal component analysis of morphophysiological and biochemical traits in sorghum under drought stress

Sorghum (Sorghum bicolor (L.) Moench) is a crucial global crop cultivated across diverse climatic conditions. This study investigates the correlation and principal component analysis (PCA) of morpho-physiological and biochemical traits in sorghum genotypes under both irrigated and rainfed conditions. Conducted at the University of Agricultural Sciences, Dharwad, the experiment involved twenty rabi sorghum genotypes planted in medium black soil, with two moisture levels: rainfed and irrigated. Correlation analysis revealed significant associations between morpho-physiological parameters and grain yield. Under drought stress, leaf chlorophyll content (SPAD) and relative water content (RWC) exhibited strong positive correlations with yield (r = 0.684 and 0.789, respectively), indicating their critical role in enhancing yield potential under water scarcity. Plant height, leaf area, and dry weight also showed positive correlations with yield, emphasizing their importance in productivity under stressed conditions. Conversely, biochemical parameters such as proline and wax content demonstrated variable correlations with yield depending on moisture availability; proline and wax content had negative correlations under irrigated conditions but positive correlations under stress, suggesting their role in drought tolerance. PCA identified the first three principal components (PC1, PC2, and PC3) accounting for significant variance in trait data. PC1, explaining 47.6% of the variance under irrigated and 56.5% under rainfed conditions, was positively associated with traits like plant height, chlorophyll content, and yield parameters, reflecting genotypic responses to productivity and drought. PC2 was linked to chlorophyll content and proline, highlighting its relevance to drought tolerance mechanisms. Overall, the study underscores the complex interplay between physiological and biochemical traits in determining sorghum's adaptability to different moisture conditions, providing insights for breeding programs aimed at improving drought resilience and yield stability.