Journal of Agronomy and Field Innovations

Climate change presents a multifaceted challenge to global agriculture, characterized by the co-occurrence of multiple environmental abiotic anomalies. While isolated drought or thermal shocks have been extensively researched, the simultaneous occurrence of combined heat and water stress represents an additive, highly disruptive biochemical challenge to crops. Pearl millet (Pennisetum glaucum L.), traditionally cultivated in arid and semi-arid geographies, stands out as an archetypal candidate for identifying climate-resilient evolutionary mechanics.
This comprehensive research investigates the morpho-physiological, anatomical, and biochemical dynamics of ten contrasting pearl millet genotypes exposed to independent and combined heat and water deficit (35% field capacity) stresses during the critical flowering stage. Over a two-year experimental timeframe, key parameters including net photosynthetic rate (A_n), stomatal conductance (g_s), chlorophyll fluorescence (F_v/F_m), relative water content (RWC), membrane stability index (MSI), and enzymatic antioxidant assays (SOD, CAT, APX) were examined.
The results show that combined stress induces an overriding physiological burden that cannot be predicted by summing the individual stresses. Genotypes PPMI-102 and PPMI-74 showed superior resilience, preserving higher photosynthetic rates, advanced cell membrane stability, and lower reductions in grain yield (<22%) under combined stress. Conversely, genotypes PPMI-15 and PPMI-44 were highly susceptible, showing severe chlorosis, photosynthetic inhibition, and high levels of cellular lipid peroxidation.
Resilient genotypes possessed distinct deep-penetrating root system architectures and robust antioxidant scavenging networks that efficiently managed reactive oxygen species (ROS). These findings provide biochemical markers and genetic candidates to guide targeted marker-assisted breeding programs aimed at developing resilient staple crops for arid farming systems.