Protective Role of Sodium Nitroprusside (SNP) in Mitigating Chilling Stress Effects in Wheat: Nutrient Homeostasis and Photosynthetic Light Reactions

BACKGROUND: Cold stress presents a serious challenge to global crop production, particularly affecting cereals such as wheat during early developmental stages. SNP enhances wheat stress tolerance by modulating nitric oxide signalling, improving antioxidant defences, growth, and yield. OBJECTIVES: The present study aimed to explores the physiological impacts of cold stress on nutrient homeostasis and photosynthetic efficiency in wheat, with emphasis on the potential mitigating effects of sodium nitroprusside (SNP). METHODS: Wheat seedlings were grown under controlled conditions. The experiment was conducted using a completely randomized design with four treatments and ten replicates. The treatments included: (1) control, (2) cold stress, (3) SNP, (4) cold stress + SNP. Each replicate consisted of one pot containing ten plants. RESULTS: Cold stress significantly reduced shoot and root growth, impaired nutrient acquisition, and disrupted photosynthetic performance, as evidenced by altered OJIP fluorescence transients and declines in key JIP-test parameters. Cold treatment led to the formation of L-, K-, and J-bands, indicating structural damage to photosystems and impaired electron transport. Nutrient uptake of essential elements such as N, P, K, Mg, and micronutrients declined notably under chilling conditions. However, SNP application significantly alleviated these detrimental effects, improving biomass accumulation, enhancing nutrient homeostasis, and partially restoring chloroplast electron transport efficiency. SNP-treated plants under cold stress exhibited higher quantum yields, better photosystem stability, and increased performance index (PItotal), suggesting enhanced resilience of the photosynthetic machinery. CONCLUSIONS: These results support the role of nitric oxide as a central player in plant stress physiology and highlight the potential of SNP as an effective treatment to enhance cold tolerance in wheat. This work provides new insight into strategies for improving crop performance under low temperatures, contributing to more resilient agricultural systems in the face of climate variability.