Nano-armored Wheat: Enhancing Heat Stress Resilience and Yield via Zinc–Salicylic Acid–Chitosan Bionanoconjugates

After the application of Zn–SA–chitosan bionanoconjugates (BNCs), the physio-biochemical responses of two wheat varieties WH-1124 (heat resistant) and WH-542 (heat sensitive) under terminal heat stress(THS) were assessed in the current study. Zn (Zinc) and SA (Salicylic acid) were slowly released by BNCs to maintain nutrient availability for plants.Application of BNCs enhanced wheat production by enhancing seedling emergence, seed vigour index, and cellular redox homeostasis through antioxidant status regulation, enhanced photosynthetic rate, and cellular and osmotic stability which are essential for stress resistance and plant growth. BNCs (0.01–0.16% w/v) administration at booting and anthesis stages fabricated cellular homeostasis by reducing oxidative damage by suppressing malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) restoring proline, and its metabolizing enzymes in flag leaf. Comparing control plants treated with, BNCs (0.08%) considerably slowed the loss of carotenoid and chlorophyll levels in both wheat cultivars. Furthermore, foliar treatment of BNCs boosted the activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, glutathione reductase, and glutathione peroxidase in both flag leaf and developing grains on exposure of late sown wheat to THS. BNCs (0.08%) not only promoted early maturity but also significantly slowed the plant height reduction from 12.6% in the control group to just 8.7%. Similarly, the reduction in spike length with awns, and grain yield per pot was controlled to just 5.5% from 7.9% in control.Early emergence, vigorous germination, and early flowering by BNCs synergistically helped the wheat plant in mitigating THS and giving better productivity by providing enough time for grain filling.