Optimizing irrigation and fertilization to improve yield, quality and resource use efficiency of greenhouse tomatoes

【Objective】 Efficient irrigation and fertilization are critical to sustaining greenhouse vegetable production. They not only improve fruit yield and quality, but also reduce resource waste and environmental risks. This paper experimentally determines the optimal water and fertilizer application for greenhouse tomatoes under drip fertigation.【Method】The experiment was conducted in a greenhouse with seven treatments: no fertilizer application (CK0); conventional flood irrigation and fertilization (CF); sufficient drip irrigation and fertilization (T1); reducing water and nitrogen applications in T1 by 20% and 10% (T2), 20% and 20% (T3), 30% and 10% (T4), 30% and 20% (T5), respectively, with all treatments including a reduction in phosphorus application (P2O5) by 40%. In each treatment, we measured growth, yield, quality, and water and fertilizer use efficiency of tomatoes. 【Result】Compared with CF, T1 increased economic yield and dry matter weight of tomatoes by 25.65% and 16.98%, respectively, while reducing fruit nitrate content by 7.94% and increasing lycopene content by 63.76%; it also increased irrigation water use efficiency (IWUE) and partial factor productivity (PFP) of fertilizer by 14.05% and 14.01%, respectively. There was no significant difference in water and fertilizer use efficiency between T4 and T5, and a moderate increase in irrigation and fertilization improved fruit yield and water and fertilizer use efficiency. The yield of T1 and T2 was 91.6 t/hm2 and 90.1 t/hm2, respectively, the highest among all treatments. The IWUE and PFP of T2 were 45.1 kg/m3 and 121 kg/kg, respectively, the highest among all treatments. Continuously supplying water and fertilizer via drip irrigation improved fruit quality both before and after harvest. Compared with CF, T3 increased average contents of vitamin C and soluble solids in the fruits by 21.59% and 11.29%, respectively, while reducing fruit nitrate content by 9.13%. 【Conclusion】Considering yield, quality, and water and fertilizer use efficiency, drip-fertigating 2 016 m3/hm2 of water, 243 kg/hm2 of nitrogen, 135 kg/hm2 of P2O5 and 375 kg/hm2 of K2O is optimal for greenhouse tomato production in the study region and regions with similar conditions.