Exploration of Water-Saving and High-Yield Irrigation Model for Tomato under Microsprinkler Irrigation with Plastic Film in a Greenhouse Based on Spatial Analysis

Abstract

The purpose of this study was to analyse the suitability of the frequency and amount of microsprinkler irrigation under plastic film technology (MSPF) in a greenhouse. This study was aimed at determining the effects of different irrigation frequency and irrigation amount of the MSPF on the quality, yield (Y), and water use efficiency (WUE) of tomato, and the optimal irrigation period and irrigation amount of tomato with MSPF were determined by spatial analysis method. Irrigation frequency was set 3 levels, 3 d (F1), 5 d (F3), and 7 d (F3), respectively. Irrigation amount was set 3 levels, 0.7 $E_{\text{pan}}$ (I1), 1.0 $E_{\text{pan}}$ (I2), and 1.2 $E_{\text{pan}}$ (I3) ( $E_{\text{pan}}$ is the diameter of 20 cm standard pan evaporation, mm), respectively. The results show that increase in the single fruit weight (SFW), transverse diameter (TD), vertical diameter (VD), total soluble solids (TSS), total soluble sugar (TSU), soluble solid content (SSC), sugar-acid ratio (SAR), soluble protein (SP), vitamin C (VC), lycopene (L), Y, and WUE of spring and autumn tomatoes was observed initially with decreasing irrigation frequency; however, decrease in all these variables was observed thereafter. Similarly, SFW, TD, VD, and SAR of spring and autumn tomatoes first added and then reduced with increasing irrigation amount, whereas TSS, SP, TSU, VC, L, and WUE exhibited an overall decreasing trend. On the basis of spatial analysis, the comprehensive score, Y, and WUE of F2I2 tomato were predicted to simultaneously reach more than 95% of the maximum, which is consistent with the earlier studies on comprehensive evaluation of yield and WUE.