Water and fertilizer are two important factors influencing crop growth, development and yield formation. To investigate their combined effects on the soil-plant system, and to find out the optimal water and organic fertilizer coupling strategy for tomato (Solanum lycopersicum L), an experiment was carried out from May to October in 2016 in the south of China. The experiment consisted of three drip irrigation quotas (150, 180, 210 m3/ha) and three organic fertilizer application amounts (2,800, 3,600, 4,400 kg/ha). A water-fertilizer treatment (abbreviated as CK) that is in line with local practice was used for comparison. The tomato marketable yield, sugar/acid ratio (SAR) and irrigation water use efficiency (IWUE), as well as the soil salinity and available nutrient concentrations were measured. The results showed that the marketable yield was highly significantly (p < 0.01) affected by irrigation or fertilization. The SAR of tomato were significantly (p < 0.05) affected by irrigation or/and fertilization. The fertilization had an highly significant (p < 0.01) effect on the concentrations of soil nutrients (N, P, K), while the coupling effect of irrigation and fertilization was not pronounced. According to the multi-index analysis and the computed result by the entropy weight coefficient model, a 180 m3/ha irrigation quota in combination with 4,400 kg/ha organic fertilizer application amount was the optimal water-fertilizer coupling strategy which owned the most satisfactory comprehensive benefits. The marketable yield, SAR and IWUE under this optimal strategy were 122.4 t/ha, 9.2, 32.4 kg/m3, respectively, and by 28.0%, 29.6% and 28.1% higher compared to that under CK.
Keywords: Drip irrigation; Entropy weight; Organic fertilizer; Solanum lycopersicum L; Water use efficiency; Yield.