Interactive effects of irrigation and fertilization on the growth and physiological characteristics of greenhouse tomatoes, Solanum lycopersicum L.

Water scarcity in China poses a significant challenge for sustainable greenhouse tomato production, necessitating strategies that optimize water use without compromising yield. While previous studies have explored irrigation and fertilization separately, comprehensive research on their combined effects using soluble organic fertilizers in arid regions is lacking. This study evaluates the interactive effects of different irrigation levels and fertilizer application patterns on the growth, physiological characteristics, water use efficiency (WUE), nutrient uptake, nitrogen use efficiency (NUE), and yield of greenhouse tomatoes. A pot experiment was conducted with three irrigation levels: I1 (90-100% field capacity), I2 (72-80% field capacity), and I3 (54-60% field capacity), and four fertilizer treatments: C1 (combined soluble organic and chemical fertilizer), C2 (soluble chemical fertilizer only), C3 (sheep manure and chemical fertilizer), and C4 (soluble organic fertilizer only). Results showed that increased irrigation significantly enhanced plant height, stem diameter, leaf area, leaf SPAD value, dry matter accumulation, nitrogen uptake, and fruit yield. Among all treatments, I1C1 achieved the highest fruit yield under sufficient irrigation, whereas the I2C1 treatment maintained a relatively high yield while notably improving root-to-shoot ratio, WUE, and nitrogen uptake, indicating an optimal balance for water-limited conditions. These findings demonstrate that integrating appropriate irrigation levels with combined fertilizer application can effectively mitigate water scarcity impacts, optimizing water savings and resource use efficiency while sustaining greenhouse tomato production in arid regions.