Managing salinity stress through microclimate control to enhance tomato productivity in arid regions

Given the increasing reliance on saline groundwater in arid regions, it is essential to assess how interacting abiotic stresses affect tomato growth, physiological performance, and productivity under different production environments. This study aimed to evaluate selected abiotic factors (including light, temperature, humidity, and irrigation water salinity), typical of Middle Eastern groundwater, that interact to influence morpho-physiological traits and yield of tomato grown under greenhouse, net house, and open field systems. Tomato plants were cultivated under the three selected environments (greenhouse, net house, and open field), combined with four salinity levels (2-5 dS m^⁻1). Growth, yield, and physiological traits were measured, including plant height, stem diameter, leaf number, fruit characteristics, yield per plant, and leaf chlorophyll indicators (SPAD and NDVI). Treatment effects were assessed statistically. Growth and yield traits exhibited significant interactive effects of environment and salinity, whereas SPAD and NDVI responded independently to each factor. Net house conditions under low salinity produced the highest fruit weight and yield, while higher salinity generally reduced performance, particularly under greenhouse conditions. Fruit weight showed strong positive relationships with vegetative growth parameters and fruit diameter. Increasing salinity consistently reduced SPAD and NDVI values, indicating declining photosynthetic capacity. Despite yield reductions under salinity stress, controlled environments partially mitigated physiological decline, with higher chlorophyll indices observed under low-salinity greenhouse conditions. SPAD and NDVI were positively correlated, confirming their consistency as indicators of plant physiological status. Salinity stress negatively affected tomato growth, physiology, and yield, with responses strongly modulated by environmental conditions. Optimizing both salinity management and growing environment is essential for sustaining tomato productivity in arid regions and controlled-environment agriculture systems.