Trade-offs and synergies of cultivars and plant growth promoters on wheat physiology and productivity

Wheat production in semi-arid regions faces escalating challenges from water scarcity, heat stress, and climatic variability, making improvements in physiological efficiency and yield stability critical for sustaining productivity. This study evaluated the combined influence of spring wheat cultivars and plant growth promoters (PGPs) on crop performance in a semi-arid climate, using a two-year (rabi 2021-22 and 2022-23) split-plot field experiment with three cultivars (DBW-187, K-1006, and K-607) and six PGPs treatments, including nitrobenzene, GA 3 , seaweed extracts, and micronutrient chelates. Measurements taken at tillering, flowering, and harvest revealed strong cultivar × PGP interactions, with DBW-187 showing superior growth and physiological traits such as higher tiller number (+18.3%), tiller production rate (+19.7%), dry matter accumulation (+18.3%), and improved SPAD, NDVI, and stomatal conductance (+9.5%). Micronutrient chelates (PGP6) emerged as the most effective promoter, enhancing tiller production (+36.0% to +50.5%), dry matter accumulation (+33.4%), leaf area index (+11.6%), and pigment concentrations, ultimately contributing to better stress tolerance and higher yield. The DBW-187 + PGP 6 combination achieved the highest productivity (5.38 t ha -1 ), representing a ∼24% yield increase over the control, while GA 3 also produced notable gains (12.8-19.4%). Overall, the results highlight that integrating nutrient-efficient cultivars with targeted PGPs especially micronutrient formulations and GA 3 offers a low-cost, sustainable pathway to enhance physiological resilience and optimize wheat performance in water-limited and heat-stressed agro-ecosystems. • DBW-187 + PGP6 increased yield to 5.38 t ha -1 (+24.1% over control). • Micronutrient chelates raised tiller count by 36% and dry matter by 33%. • DBW-187 recorded +19.7% tiller rate and +9.5% stomatal conductance. • GA 3 treatment enhanced grain yield by 12.8–19.4% across cultivars. • Cultivar–PGP synergy improved LAI (+11.6%) and photosynthetic efficiency.