Seed priming and thermal seed treatments alleviate yield losses in late-sown wheat across two field locations

Background Wheat sowing is delayed in Rice-Wheat and Cotton-Wheat rotations. It exposes late-sown wheat to low and high temperature stresses at germination and grain development stages, respectively, affecting the growth and productivity of wheat. Therefore, this study evaluated the effect of late-sowing on wheat performance and the potential of seed treatments to alleviate yield losses in late-sown wheat. Field experiments were conducted during 2021–2022 at Bahawalpur (EL1) and Multan (EL2), Pakistan. A split-plot randomized complete block design with three replications was used at both locations, with sowing date as the main-plot factor and seed treatment as the subplot factor. Sowing was performed on 15 November 2021 for recommended sowing, and 15 December 2021 for delayed sowing at both experimental locations. Seeds were subjected to five treatments: heat treatment, cold treatment, zinc priming, proline priming, and an untreated control. Results Late sowing reduced grain yield of untreated plants by 38.6% at Bahawalpur and 67.5% at Multan and decreased their germination index by 21.4% and 25.8%, respectively. It also reduced plant growth, spike development, and yield-related traits, although the magnitude of these effects differed between locations. Heat treatment improved germination under late-sown conditions and produced the highest late-sown grain yield at Bahawalpur (5.11 t ha⁻¹). Zinc priming produced the highest late-sown grain yield at Multan (2.48 t ha⁻¹), while zinc and proline priming generally improved growth, spike traits, physiological performance, and grain yield. Zinc and proline priming also enhanced antioxidant responses, although treatment effects were location-dependent. Cold treatment provided no consistent benefit and resulted in poor crop establishment under delayed sowing at Multan. Conclusions Delayed sowing significantly affected germination, growth and yield of wheat. Based on this one season and two locations study, heat treatment, zinc priming and proline priming showed potential for improving late-sown wheat performance, whereas cold treatment was unreliable under the tested conditions. However, broader multi-season and multi-location validation is required before general recommendations are made.