Performance Evaluation for Yield Traits in Garden Pea (Pisum sativum L.) Genotypes Across Differential Thermal Environments

Garden pea (Pisum sativum L.) is a nutritionally important cool-season legume, but its productivity is highly constrained by heat stress, particularly during reproductive stages. Rising temperatures and increasing climatic variability necessitate the identification of heat-tolerant and stable genotypes to sustain yield under diverse thermal environments. The present study was undertaken to examine garden pea (Pisum sativum L.) genotypes for yield and its associated traits under varying thermal conditions, with the objective of identifying stable and heat-tolerant lines. The field experiment was laid out in an Augmented Block Design at the Vegetable Research Centre, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India, during the rabi season of 2024–2025. A total of 72 diverse test genotypes along with two standard check varieties (PM-128 and PSM-3) were evaluated under three different thermal regimes, namely pre-flowering heat stress (Environment 1), optimum conditions (Environment 2), and terminal heat stress (Environment 3). Heat stress conditions were imposed through staggered sowing dates, with early sowing exposing the crop to higher temperatures during the vegetative stage and late sowing subjecting the crop to elevated temperatures during the reproductive phase. Observation were recorded on important phenological and yield-related traits. Pre-flowering heat stress (Environment 1) led to accelerated flowering and reduced vegetative growth, with comparatively moderate effects on yield traits relative to terminal heat stress. The crop performed best under optimal conditions (Environment 2), whereas a marked decline in yield attributes was evident under terminal heat stress (Environment 3), particularly for pod number, seed set, and overall pod yield. Among the entries, PSM-151, PM-128, PSM-3, PSM-166 and PSM-221 consistently exhibited better and consistent performance across environments, indicating their relative tolerance to heat stress. On the other hand, genotypes such as PSM-152 and PSM-202 were found to be more susceptible, especially under late-season heat stress. The findings indicate that heat stress imposed during the reproductive phase has a pronounced adverse effect on yield in garden pea. Genotypes demonstrating consistent performance across environments, such as PSM-3, PM-128 and PSM-151 may serve as promising material for breeding programmes aimed at developing heat-resilient cultivars. However, further evaluation across locations and seasons would be necessary to confirm their wider adaptability.