Vermicompost Improves Resilience to Drought through Changes in Morpho-Physiological and Biochemical Traits in Wheat Seedlings

Drought stress poses a major threat to the morphological and physiological processes of wheat. Vermicompost application can help alleviate these effects under water scarcity. This study investigated the protective role of rice straw vermicompost on the nutritional, biochemical, morphological, and physiological traits of wheat seedlings exposed to different drought levels. Three drought regimes – control (CK, 70% field capacity), moderate drought (MD, 45% field capacity), and severe drought (SD, 30% field capacity) – were combined with four vermicompost treatments – RVC-0 (control, no vermicompost), RVC-1 (4 t ha− 1), RVC-2 (6 t ha− 1), and RVC-3 (8 t ha− 1), applied to two wheat cultivars, Faisalabad-08 and Galaxy-13. Vermicompost application significantly improved growth traits, including root and shoot fresh and dry weights, with the most pronounced effects observed at RVC-2, under both moderate and severe drought conditions. RVC-2 also resulted in the highest stomatal conductance and chlorophyll content in both cultivars. Under severe drought, RVC-2 increased stomatal conductance by 14.38%, sub-stomatal CO2 concentration by 11.36%, total chlorophyll by 11.55%, carotenoids by 7.63%, and ascorbate peroxidase activity by 26.74% compared with the control. Moreover, RVC-2 enhanced the uptake of essential nutrients (N, P, and K) under both well-watered and drought conditions. Overall, Faisalabad-08 demonstrated greater drought tolerance than Galaxy-13, as reflected in its superior morphological, physiological, and biochemical performance. The study concludes that rice straw vermicompost, particularly at 6 t ha− 1 (RVC-2), is effective in mitigating the adverse effects of drought on wheat growth and physiology.