ASSESSMENT OF GENETIC VARIABILITY FOR SEED VIGOUR UNDER HIGH-TEMPERATURE STRESS IN SUNFLOWER USING TEMPERATURE INDUCTION RESPONSE (TIR) TECHNIQUE
DOI:
https://doi.org/10.48165/abr.2026.28.01.40Keywords:
Chlorophyll stability index, heat stress, sunflower, superoxide dismutase, temperature inductionAbstract
Climate change and global warming are intensifying the frequency and severity of heat stress, posing a major threat to crop growth, development, and productivity. Rising temperatures adversely affect key physiological and biochemical processes, particularly during critical stages of crop development. In this context, rapid and reliable screening techniques are essential for evaluating large numbers of genotypes and identifying heat-tolerant sources. The present study was conducted to evaluate the response of thirty sunflower genotypes to temperature induction under laboratory conditions and to identify potential heat-tolerant genotypes. Significant genotypic variation was observed among the genotypes for all the traits evaluated, indicating substantial genetic diversity in response to temperature stress. Seedling survival ranged from 35.0 to 90.0%, while root growth reduction varied from 0.0 to 34.3%. The chlorophyll stability index (CSI) and Superoxide dismutase (SOD) activity declined following temperature induction; however, the magnitude of reduction differed considerably among genotypes. Genotypes ‘PHT 6’, ‘NDI 26’, ‘NDSH 1012’, ‘NDI 55’, and ‘SH 2602’ maintained higher chlorophyll stability and antioxidant enzyme activity, suggesting enhanced cellular protection against stress. Genotypes ‘PB 1340’, ‘NDI 30’, ‘PB 1351’, and ‘PB 1356’ exhibited greater reductions in physiological and biochemical traits, indicating greater susceptibility to heat stress. The study identified ‘PHT 6’, ‘NDI 26’, ‘NDSH 1012’, ‘NDI 55’, and ‘SH 2602’ as promising sources of heat tolerance. These genotypes may serve as valuable genetic resources for development of temperature-resilient sunflower cultivars through future breeding programmes.
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