What question did this study set out to answer?

The aim is to characterize rice genotypes for drought tolerance through physiological and biochemical traits.

March 21, 2026

Physiological and Biochemical Characterization of a Core Germplasm Set Reveals Superior Genotypes for Enhanced Stress Tolerance in Rice (Oryza sativa L.)

USU. S. Sreevathsa SagarTamil Nadu Agricultural University RPR. PushpamTamil Nadu Agricultural University MRMuthuraja RaveendranTamil Nadu Agricultural University

Key Points

The aim is to characterize rice genotypes for drought tolerance through physiological and biochemical traits.
Developed a core set of 16 rice genotypes from 150 accessions
Evaluated under drought and irrigated conditions
Measured traits like relative water content, membrane stability index, and antioxidant enzyme activities
Conducted correlation analysis and principal component analysis to assess traits and variations
Significant genotypic variation was found across traits under both conditions
Yield under drought positively correlated with superoxide dismutase, membrane stability index, and relative water content
Superior drought adaptation observed in genotypes RL-5750, RL-9815, and RL-4499
Genotypes RL-671, RL-2503, and RL-1682 demonstrated better performance under irrigation

Abstract

Drought is one of the most critical abiotic stresses limiting crop productivity by disrupting cellular water balance, inducing oxidative stress, and impairing photosynthetic metabolism. In rice (Oryza sativa L.), drought triggers a cascade of physiological and biochemical adjustments that determine genotypic resilience, including enhanced antioxidant activity, osmotic regulation, and membrane protection. To elucidate these adaptive mechanisms, a core set of 16 rice genotypes was developed from an initial panel of 150 accessions, representing maximum physiological and biochemical diversity. These genotypes were evaluated under drought and irrigated conditions for key traits such as relative water content (RWC), membrane stability index (MSI), nitrate reductase (NR) activity, peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), proline (PRO), SPAD chlorophyll index, and yield. Significant genotypic variation was observed across all traits. Correlation analysis revealed that yield under drought was positively associated with SOD, MSI, and RWC, highlighting the critical role of antioxidant defense and cellular water retention in sustaining photosynthetic function. Principal component analysis (PCA) efficiently captured the multidimensional variation among genotypes, while the Multi-Trait Genotype–Ideotype Distance Index (MGIDI) enabled integrated selection for physiological and biochemical efficiency. Genotype 5(RL-5750), 6(RL-9815) and 4(RL-4499) exhibited superior adaptive responses under drought, whereas genotype 1(RL-671), 3(RL-2503) and 2(RL-1682) performed best under irrigation. This integrative physiological framework demonstrates that drought tolerance in rice is governed by coordinated antioxidant regulation, membrane stability, and tissue hydration. The findings provide a mechanistic basis for identifying physiological markers and elite genotypes, offering valuable resources for breeding programs aimed at improving drought resilience and yield stability in rice.

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