Gypsum and press mud application alleviate the deleterious effects of sodic water irrigation in Guava (Psidium Guajava L. cv. Taiwan Pink)

Guava is a major fruit crop in sodic soil regions of north-western India. However, the responses of guava to sodic irrigation in terms of growth, physiology, and fruit quality remain elusive. This study evaluated the effects of sodic irrigation with varying residual sodium carbonate (RSC; 2.5-7.5 meq L⁻¹), with or without amendments (gypsum and press mud), on the growth, physiological traits, mineral nutrition, and fruit quality of guava cv. Taiwan Pink over two consecutive seasons. Sodic irrigation markedly suppressed plant growth, including height, canopy spread, stem girth, leaf area, and branching, with greater reductions at higher RSC levels (5.0-7.5 meq L⁻¹). Photosynthetic rate, leaf chlorophyll content, relative water content, osmotic potential, and membrane stability also declined under sodicity stress, whereas proline accumulation and antioxidant enzyme (ascorbate peroxidase, catalase, peroxidase, and superoxide dismutase) activities increased, reflecting adaptive responses to sodicity-induced osmotic and oxidative stresses. Sodic conditions reduced leaf K⁺, Ca²⁺, and Mg²⁺ contents and increased Na⁺ accumulation. Despite these physiological and biochemical disruptions, fruit quality attributes remained largely stable across treatments. Principal component analysis indicated strong interrelationships among growth and physiological traits, whereas fruit quality traits formed a distinct cluster, and Na⁺ accumulation and stress indicators were negatively associated with plant vigor. Gypsum was more effective than press mud in alleviating sodicity stress, enhancing the plant growth, increasing photosynthetic rate (~ 10%) and chlorophyll content (4-6%), and reducing leaf Na⁺ (9.8-38.2%) across RSC levels, compared to comparatively smaller improvements achieved with press mud. Overall, the findings indicate that Taiwan Pink guava can tolerate moderate sodicity without appreciable declines in fruit quality, and that soil amendments- especially gypsum- effectively improved plant growth and physiological performance under sodic irrigation.