EFFECTS OF AERATED IRRIGATION AND NITROGEN APPLICATION ON TOMATO YIELD AND NITROGEN ABSORPTION IN GREENHOUSE ENVIRONMENT.

Aerated irrigation (AI) has the potential to be an effective management strategy to further increase yield and nitrogen-use efficiency. To determine the correlation between aerated irrigation and nitrogen application, we conducted a greenhouse experiment in Zhengzhou, Henan, China. A two-factor, three- level experiment was set up in which three aeration rates of dissolved oxygen in irrigation water (A1 = 5 mg/L, A2 = 15 mg/L, and A3 = 40 mg/L) and three nitrogen application rates (N1 = 120 kg/hm², N2 = 180 kg/hm², and N3 = 240 kg/ hm²) were set by using randomized block testing. CK is normal subsurface irrigation without fertilization and aeration, seemed as a control treatment. The analysis of variance, correlation analysis, and structural equation model (SEM) clarify how each factor affects the yield and nitrogen absorption and the utilization of greenhouse tomatoes. (Results) The results show that aerated irrigation significantly improves the nitrogen uptake efficiency and tomato yield (p < 0.05). Compared with the non-aerated treatment, the tomato yield after aerated irrigation increased by 13.35%-29.73%, and the highest tomato yield was 250.42t/hm² under treatment A2N3. Compared with treatments A1N3 and A3N3, the yield of treatment A2N3 increased by 29.73% and 11.53%, respectively, and the tomato nitrogen absorption efficiency increased by 53.06% and 18.33%, respectively (p < 0.05). Under the action of a single factor, applying nitrogen under aerated conditions can increase tomato yield and nitrogen absorption. According to SEM analysis, aeration and nitrogen application are positively correlated to a significant extent with tomato nitrogen absorption and indirectly correlated positively with tomato yield; the path coefficients are 0.969 and 0.927, respectively. Therefore, the combination of aeration and nitrogen application can further increase yield and nitrogen absorption efficiency, and the aeration amount A2 (15 mg/L) and the nitrogen application rate N3 (240 kg/hm²) are the best combination to increase the nitrogen uptake and yield of tomatoes. The results of this research provide technical support for optimizing gas-nitrogen coupled drip-irrigation and should help to popularize the use of gas-nitrogen coupled irrigation. [ABSTRACT FROM AUTHOR]