Evaluating effect of micro-spray on tomatoes for resisting summer heat stress using a Fuzzy Borda combination evaluation model

Micro-spray is commonly used to improve the growing environment of plants to avoid growth inhibition due to high temperatures in greenhouses in summer. In this study, the effects of micro-spray on growth and physiological characteristics of tomato plants grown in a Venlo-type greenhouse were observed using a combined micro-spray and drip irrigation (MSDI) system for two growing. Therefore, four single integrated evaluation methods, TOPSIS, PCA, RSR, and VIKOR were used to evaluate the different indicators in an integrated manner to avoid the limitation of a single indicator under two irrigation methods. The results of the study showed that the values of effective quantum yield of PSII (ФPSII) for tomatoes cultivated under MSDI treatment were higher than those obtained under DI treatment. However, when the air temperature was below 35 °C and photosynthetically active radiation (PAR) was below 820 μ mol/m²/s, the increase in ФPSII value was ranged from 13% to 23% under MSDI. Once the air temperature exceeded 35 ℃, then a short time (1 min) micro-spray was less effective in relieving heat stress; and the increase of ФPSII ranged from 6% to 13%. Meanwhile, it was found that the TOPSIS, PCA, and RSR were suitable for studying the rapid quality evaluation of the tomato cultivated under MSDI because their ranking results had a high Spearman correlation coefficient of 0.965 with the Fuzzy Borda combination evaluation (FB) model. Comprehensively evaluating the quality of tomatoes cultivated under different irrigation methods, the results of the FB model proved that the MSDI was better than the DI because the comprehensive score of the MSDI was higher than the DI. MSDI took up five spots in the top six scores in the two years of the FB model.