Unveiling Drought Tolerance Biomarkers in Cocoa: A Comparative Study under Controlled and Field Conditions

Abstract

Drought stress poses a significant threat to cocoa (Theobroma cacao L.) cultivation, particularly as climate variability disrupts traditional rainfall patterns in expanding cocoa growing regions of India. This study aimed to identify reliable biochemical biomarkers indicative of drought tolerance in cocoa by comparing biochemical responses of eleven hybrids under controlled nursery and field-imposed drought conditions, and was conducted at KAU Vellanikkara, Thrissur. Four key biochemical parameters including proline, nitrate reductase activity (NRA), superoxide dismutase (SOD), and glycine betaine were quantified and analysed using paired t-tests. Results revealed statistically significant differences in SOD and glycine betaine levels between nursery and field conditions, while proline and NRA exhibited consistent responses across environments. Tolerant hybrids maintained higher proline and NRA levels under drought, highlighting their potential as predictive biomarkers for early-stage drought screening. This comparative approach bridges the gap between controlled and field research, offering a practical strategy for accelerating the selection of drought-resilient cocoa genotypes. The findings underscore the utility of integrating biochemical markers into breeding programs to enhance climate resilience in cocoa cultivation.