Genotypic Variation in Fodder Cowpea (Vigna unguiculata (L.) Walp.) for Adaptability to Heat Stress: An Evaluation of Growth, Physio-Biochemical Traits and Fodder Quality

Abstract

Climate change poses a significant threat to global agriculture due to the combined effects of rising temperatures and fluctuating atmospheric CO₂ levels. Fodder cowpea (Vigna unguiculata (L.) Walp.), a climate-resilient legume, holds great promise as a sustainable forage source for livestock under such challenging conditions. The present study was conducted at the Department of Genetics and Plant Breeding, College of Agriculture, Vellayani, to evaluate thirty fodder cowpea genotypes for their performance under heat stress. The experiment was carried out in contrasting field and polyhouse environments, with the polyhouse maintained at approximately 4°C higher temperature and a CO₂ concentration of around 409 ppm compared to 405 ppm in the field. Biometric, physiological and quality traits were assessed to determine genotypic responses under these environments. Significant variability was observed among genotypes indicating the presence of substantial genetic diversity for adaptive traits. Plants grown under polyhouse conditions exhibited significantly enhanced biomass accumulation (up to 22% higher), while those in the field environment showed around 18% higher crude protein content reflecting environmental influences on trait expression. Crude fibre content showed a 6.9% increase under polyhouse compared to field conditions. The genotypes EC240630, BL4, MFC-09-1 and COFC-8 were identified as promising entries demonstrating superior performance across several traits representing valuable genetic resources for breeding programs aimed at developing high-yielding, climate-resilient fodder cowpea varieties.