Suitable water-fertilizer-gas coupling model under drip irrigation for processing tomato based on yield，quality and carbon emission

The purpose of this study was to investigate the effects of water-fertilizer-gas coupling under drip irrigation on yield and quality of processing tomato and CO₂ emissions from processing tomato land, and to screen out better treatments that take into account high yield and quality, reduce greenhouse gas emissions and improve economic efficiency. A field tiral was conducted in 2023 at the Key Laboratory of Modern Water-saving Irrigation, Shihezi University, Shihezi City, Xinjiang, China. A three-factor completely randomised trial was set up using irrigation level, humic acid addition and aerating method. The local conventional irrigation level was 4500 m³/hm² , so the irrigation level was set at 4500 m³/hm² (W2) and 3800 m³/hm² (W1). The humic acid addition was set at three levels, 0 (H0), 0.25% (H1) and 0.50% (H2), and the aerating method was conventional sub-film drip (A0) and micro-nano aerated drip (A1). The tomaoto yield and its components were determined. The quality of tomato was evaluated. In addition, the green house gas emissions from the filed were also measured and the net profit of processing tomatoes was calculated. The results showed that, in terms of carbon emission and carbon sequestration, the cumulative CO₂ emission flux, initial carbon productivity and net carbon sequestration under the W2 treatment were significantly increased by 17.14%-25.36%, compared with the W1 treatment; and those under H2 treatment were significantly increased by 11.48%-12.26% compared with H1 treatment. In terms of yield, weight, number of fruits, weight of single fruit and irrigation water use efficiency of processing tomato were significantly increased by 8.86%-19.87% (P＜0.05) in the W2 treatment compared to the W1 treatment, but the vitamin C, soluble sugar, titratable acid, soluble solids, and lycopene content of processing tomatoes were significantly reduced by 4.77%-14.58% (P＜0.05). Tomato yield, number of fruits, weight of single fruit, irrigation water use efficiency, vitamin C, soluble sugar, soluble solids, and lycopene were increased by 5.25%-29.32% in the H2 treatment compared with H0 treatment (P＜0.05). However, the titratable acid content in the H2 treatment was significantly 11.21% lower than that in the H0 treatment (P＜0.05).Tomato yield, single fruit mass, irrigation water use efficiency, vitamin C, soluble sugar, soluble solids, and lycopene were increased by 15.23%-35.65% in the A1 treatment as compared to the A0 treatment (P＜0.05). A comprehensive evaluation was conducted by means of three evaluation methods, namely the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS), the Rank Sum Ratio (RSR) method, and Principal Component Analysis (PCA) based on 12 evaluation indicators from four aspects: yield, quality, economic benefit, and environmental indicators (carbon emissions and carbon sequestration) and the result showed that the coupling drip irrigation model combining an irrigation level of 3 800 m³/hm², an application rate of 0.5% humic acid, and micro-nano aeration achieved the highest comprehensive evaluation score. It is recommended as the optimal water-fertilizer-gas coupling mode for high-yield, high-quality, emission reduction, and efficiency enhancement of processing tomatoes. This research can provide a technical support for the high-yield, high-quality, and emission reduction of drip-irrigated processing tomatoes in the arid area of northern Xinjiang.