Fuzzy comprehensive evaluation on regulated deficit irrigation scheduling of tomato drip irrigated in solar greenhouse

Abstract: This study aimed to investigate the feasibility of improved fuzzy comprehensive method in the evaluation of regulated deficit drip irrigation scheduling in solar greenhouse. An experiment was conducted in a solar greenhouse from March to July, 2015 and 2016 at Xinxiang Comprehensive Experimental Station, Chinese Academy of Agriculture Sciences (35°9? N, 113°5? E and altitude 78.7 m). The experimental soil was loam at 0-80 cm and sandy loam at 80-100 cm. The solar greenhouse frame had a steel frame, covering an area of 510 m2 (60 m by 8.5 m). The roof of solar greenhouse was covered with 2.5-cm thick cotton wadding and the heat-insulating materials were embedded in the wall to maintain the interior temperature. Irrigation scheduling was determined based on the accumulated evaporation in a standard pan in the diameter of 20 cm. The experiment was designed with full irrigation (0.9 times of the accumulated pan evaporation), mild water deficit (0.7 times of the accumulated pan evaporation) and moderate water deficit (0.5 times of the accumulated pan evaporation) in the flowering and fruit setting stage and the mature picking stage. There were 18 plots, and the plot area was 8.8 m2 (8.0 m by 1.1 m). The crop growth index, yield index, water consumption index and quality index of drip-irrigated tomato were evaluated by using the improved fuzzy comprehensive method. The weight was obtained by 10 expert's scores. The results showed that the crop growth index, yield index and water consumption index of tomato increased with the irrigation amount without considering the water deficit at different stages, but the quality index was decreased. Effect of the mild water deficit on quality index was weak, and the comprehensive evaluation index of growth index and yield index in the mature picking stage was higher than that in the flowering and fruit setting stage, while the crop evapotranspiration and irrigation amount over the whole growth stage of the former was lower. For the mild deficit irrigation for both growing stages, the quality comprehensive evaluation index was similar (0.135 and 0.138, and 0.125 and 0.124). For the moderate water deficit, the comprehensive evaluation index of growth index, yield index and quality index in the flowering and fruit setting stage was similar to that in the mature picking stage, but the crop evapotranspiration over the whole growth stage of the latter was lower. Therefore, for the drip-irrigated tomato in solar greenhouse, the mild water deficit in the mature picking stage should be recommended to the region with abundant water resource, while for the region with limited water resource, the moderate water deficit in the flowering and fruit setting stage should be applied. The improved fuzzy comprehensive evaluation method was recommended as a basis for evaluating regulated deficit irrigation system of drip-irrigated tomato in solar greenhouse.