Improving Water Use Strategies in Greenhouse Tomato with Superabsorbent Polymers: Effects on Fruit Yield Under Deficit Irrigation

Summary

Water scarcity is increasingly challenging greenhouse tomato production, particularly in Mediterranean and semi-arid regions where irrigation water availability is becoming progressively limited. This study evaluated whether a superabsorbent polymer (SAP) can support water-saving irrigation in tomato grown in coconut fibre. Plants were cultivated in pots under four irrigation amounts (100, 75, 50, and 25% of crop water requirement—WC) combined with two SAP levels (0 and 2 g L−1). Irrigation was managed by a lysimetric control system. Reducing irrigation decreased total fruit yield (averaged across SAP treatments) from 100% WC (1212 g plant−1) to 50–25% WC (914 and 624 g plant−1, respectively), while non-marketable fruit number was unchanged (15.4 fruit plant−1, on average). SAP increased t