Response of Rice Genotypes to Temperature Stress During Flowering: Implications for Climate Change Adaptation in Nigeria

This study examines the response of rice genotypes to temperature stress during flowering and derives implications for climate change adaptation in Nigerian rice production. Rising temperatures associated with climate change are projected to increase the frequency of heat stress events during the temperature-sensitive flowering stage of rice, potentially causing significant spikelet sterility and yield losses. Understanding the heat tolerance of rice genotypes currently used in Nigeria is essential for identifying vulnerable production systems and prioritising heat-tolerant variety development. This study subjects 24 rice genotypes widely grown in Nigeria including FARO 44, FARO 57, NERICA L-19, NERICA L-34, and local varieties to controlled high temperature treatments of 35, 38, 41, and 44 degrees Celsius for 2 hours during anthesis in climate-controlled growth chambers at the National Cereals Research Institute Badeggi. Pollen viability, spikelet sterility, harvest index, and grain yield under stress and non-stress conditions are measured. Heat susceptibility index is computed for each genotype. Findings reveal that all genotypes show significant spikelet sterility above 38 degrees Celsius, with mean sterility ranging from 12 to 68 percent at 41 degrees Celsius across genotypes. NERICA varieties show consistently lower heat susceptibility indices than FARO varieties, suggesting genetic variation suitable for climate adaptation. Pollen viability declines sharply above 38 degrees Celsius in heat-susceptible genotypes. The study contributes original heat stress screening data for Nigerian rice varieties and recommends prioritisation of heat-tolerant NERICA genotypes in climate change adaptation breeding programmes.

Keywords: rice, heat stress, spikelet sterility, climate change adaptation, Nigeria.