Responses of Tomato Crop and Water Productivity to Deficit Irrigation Strategies and Salinity Stress in Greenhouse

Abstract

Saudi Arabia faces water scarcity and inadequate sustainable sources, particularly in agriculture, necessitating efficient irrigation water management to improve productivity amidst rising demand. The study investigated the impact of irrigation levels and water salinity on tomato plants in greenhouses, covering four irrigation levels (100%, 80%, 60%, and 40% of ETc) and three water sources (FW (0.9 dS·m−1), SW (3.6 dS·m−1) and MW (2.25 dS·m−1)). Salinity impacts crop yield, physiological responses, and fruit quality. The photosynthesis, stomatal conductance, transpiration, and chlorophyll content decrease with MW and SW, negatively affecting morphological characteristics. For MW, it was recommended to apply 60% deficit irrigation with a yield of 98 kg·ha−1, and water productivity (WP) improved to 21.93 kg·m−3 compared to 13.65 kg·m−3 at full irrigation (FI). In SW, 80% irrigation was suggested, as there was no significant difference in yield compared to FI. For FW, 60% deficit irrigation produced the best water conservation (104.58 kg·ha−1 yield and 23.19 kg·m−3 WP), while FI produced the highest yield per unit area (123.48 kg·ha−1 yield and 16.51 kg·m−3 WP). Nonetheless, greater water and salinity stress was associated with increased fruit quality measures such as total acidity, vitamin C, and soluble solids. The results show that implementing deficit irrigation with salinity strategies in greenhouse tomatoes could improve crop adaptability, yield, and water productivity in the face of water scarcity and salinity variability.

Evaluating Tomato Performance: A Novel Approach of Combining Full and Deficit Irrigation with Saline Water

“…Osmotic stress causes a drop in Chl-I levels, which damages chloroplast layers by increasing the membrane permeability [48]. These results are in line with previous studies, which have demonstrated that environmental stressors, including dryness and salt stress, cause tomato leaves to lose their photosynthetic pigments [31,49].…”

“…The deficit irrigation considerably reduced the h, WS w , WS d , LA, and ST, indicating the mechanisms intended for conserving water, such as decreased expansion of cells, altered hormonal balance, and resource allocation prioritizing surviving overgrowth [61,62]. This finding was in line with earlier studies by Agbna et al [20], Chand et al [22], Colimba-Limaico et al [63], Wu et al [64], and Alshami et al [31], which indicate that salinity and water stress cause a considerable loss of many morphological characteristics. The magnitude of this reduction is influenced by the level and duration of the irrigation stress.…”

“…According to the results in Table 3, the P n , gs, Chl-I, and T r values consistently dropped as water salinity levels increased, consistent with various studies' findings [31,40]. This behavior is because irrigation water with higher salinity causes water stress, which lowers the P n by changing stomatal regulation and limiting carbon dioxide absorption [41].…”

“…Water stress causes a decrease in P n through the stomatal closure mechanism, which counteracts water loss and thus lowers the uptake of carbon dioxide. Previous research showed a connection between a reduced P n and water stress [20,31,[50][51][52]. Wong et al [53] and Tuzet et al [54] showed that the g s has a reciprocal regulatory effect on the P n and T r .…”

“…Full irrigation resulted in the greatest fruit yield, while a severe water deficit during flowering lowered yields. Alshami et al [31] investigated the impact of various irrigation and water salinity levels on greenhouse tomato cultivation in Saudi Arabia. The study employed four irrigation levels, 100%, 80%, 60%, and 40% of ET c , and three distinct water concentrations, 0.9, 2.25, and 3.6 dS•m −1 .…”