The elucidation of heat tolerance mechanisms is required to combat the challenges of global warming. This study aimed to determine the antioxidant enzyme responses to heat stress, at the enzymatic activity and gene expression levels, and to investigate the antioxidative alterations associated with heat tolerance in the stems and roots of squashes using three genotypes differing in heat tolerance. Plants of heat-tolerant “C. moschata”, thermolabile “C. maxima” and moderately heat-tolerant interspecific inbred line “Maxchata” genotypes were exposed to moderate (37 °C) and severe (42 °C) heat shocks. “C. moschata” exhibited comparatively little oxidative damage, with the lowest hydrogen peroxide (H₂O₂), superoxide (O₂⁻) and malondialdehyde (MDA) contents in the roots compared to stems, followed by “Maxchata”. The enzyme activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POD) were found to be increased with heat stress in tolerant genotypes. The significant inductions of FeSOD, MnSOD, APX2, CAT1 and CAT3 isoforms in tolerant genotypes suggested their participation in heat tolerance. The differential isoform patterns of SOD, APX and CAT between stems and roots also indicated their tissue specificity. Furthermore, despite the sequence similarity of the studied antioxidant genes among “C. maxima” and “Maxchata”, most of these genes were highly induced under heat stress in “Maxchata”, which contributed to its heat tolerance. This phenomenon also indicated the involvement of other unknown genetic and/or epigenetic factors in controlling the expression of these antioxidant genes in squashes, which demands further exploration.

The use of environmentally friendly approaches to improve crop productivity has gained considerable attention in sustainable vegetable production. This study was conducted during the summer of 2022 at the Horticulture Research Farm, The University of Agriculture, Peshawar, Pakistan, to evaluate the effects of Trichoderma harzianum and acetylsalicylic acid (ASA) on the growth and yield of chilli (Capsicum annuum L.) cv. P6. The experiment was arranged in a factorial Randomised Complete Block Design with three replications, comprising four levels of T. harzianum (0, 2, 4, and 6 kg ha-1) and four concentrations of ASA (0, 100, 200, and 300 mg L-1). The main effects of T. harzianum and ASA significantly improved plant growth, chlorophyll content, fruit characteristics, ascorbic acid content, and yield, while reducing the number of days to flowering and fruit set and disease incidence, compared with the untreated control. The highest levels of T. harzianum and ASA generally produced superior responses for most measured traits. However, the interaction between T. harzianum and ASA was generally not significant across all studied parameters. Overall, the individual application of T. harzianum and ASA demonstrated potential as environmentally friendly approaches for enhancing the growth, yield, and fruit quality of chilli under the agro-climatic conditions of Peshawar.