Simulation And Validation Of Tomato Water Consumption Model In Greenhouse

This experiment selected potted tomato “Jinpeng No.1” as materials, included4cultivations. Cultivation1was from Mar.14to Jun.18in2011, cultivation2and3were fromApr.5to Jun.27in2011, and cultivation4was from Sep.2to Oct.25in2011. In cultivation1and2, three water treatments were designed as supplementary irrigation of60%,80%and100%of transpiration with the same initial relative soil water content. The correlation betweendaily transpiration of pot planted tomato in greenhouse and impact factors was studied, such astotal leaf area per tomato plant, soil relative water content, temperature, relative humidity andsolar radiation, etc., and a regression function for estimating daily transpiration of greenhousetomato established. In cultivation3and4, tree water treatments were designed assupplementary irrigation of100%transpiration with the different daily initial soil watercontents of100%,85%and70%. An estimation model of transpiration per day was establishedfor greenhouse tomato in vegetative growth period by analyzing parameters under differentwater treatments. The model parameters were estimated by measuring data from Apr.17to May16in2011. The model was verified by measured data from Sep.30to Oct.19in2011. Themean results were as follows:1. The impact factors of daily transpiration of tomato in greenhouse were analysed byPearson correlation analysis and path analysis. The correlations between daily transpiration oftomato in greenhouse and impact factors except daily minimum temperature were remarkable,especially the correlations of total leaf area per plant, relative soil water content, daily meantemperature, daily mean relative humidity, daily maximum relative humidity, daily minimumrelative humidity and daily maximum intensity of solar radiation were significant. Thestrongest direct positive impact factor of potted tomato daily transpiration in greenhouse wasdaily minimum relative humidity, and the strongest direct negative impact factor was dailyminimum temperature, the direct path coefficients were0.742and–0.515, respectively. Thefactors of total leaf area per plant, relative soil water content, daily mean temperature, dailyminimum temperature and daily minimum humidity impacted on transpiration in direct way.The factors of daily maximum temperature and daily mean relative humidity impacted ontranspiration in indirect way positively. The factors of daily maximum relative humidity, dailymaximum intensity of solar radiation and daily solar radiation intensity accumulation impactedon transpiretion in indirect way negatively. Complicated interactions among impact factors of transpiration comprehensively effecteddaily transpiration of greenhouse tomato by enhancing or restricting impact factors. Soilrelative water content was the main decision factor, the decision coefficient was27.39%. Dailyminimum relative humidity was the main limiting factor, and daily minimum temperature wasthe less important limiting factor, the decision coefficients were–119.68%and–34.44%,respectively. That the decision coefficient of residual factor ε was18.81%indicated that someother impact factors were not yet considered.The regression function for estimating established by path analysis and multiple linearregression analysis with less variables could better fit the observed value, and R2=0.74(n=40),RMSE and RE were respectively76.56g and20.26%. The regression model had good stabilityin trend.2. Based on5hypotheses from the perspective of stomatal conductance and dailytranspiration of unit leaf area, a model for estimating daily transpiration of tomato ingreenhouse was established and verified by analysis of impact factors. The result showed thataverage relative error for the model simulation was13.24%,15.64%and14.70%underdifferent water treatments, respectively. Therefore, tomato transpiration per day in vegetativegrowth period could be estimated using the model. This study was a useful attempt for researchon crop transpiration simulated model in greenhouse, and could be helpful to intensive study oftomato water management in greenhouse.