Effect Of Water-Gas Coupled Drip Irrigation And Reduced Potassium Application On The Growth And Soil Environment Of Tomato In Greenhouse

Unscientific water and fertilizer management has caused problems such as salinization of greenhouse soils,leading to a decline in crop yield and quality,and severely limiting the sustainability of facility agriculture.However,it is worthwhile to further investigate whether water-gas coupled irrigation can promote potassium uptake and utilization by crops,so that reduced potassium application can also increase crop yield and quality.To investigate the combined effect of water-gas coupled drip irrigation and potassium application on greenhouse tomato cultivation,this study was based on a greenhouse field trial with tomato as the test crop,K3,K4),for a total of 8 treatments.The results of the measurements and analyses of greenhouse tomato growth and physiology,yield quality,root zone soil environment and potassium uptake and utilization efficiency provided theoretical and scientific basis for the study of greenhouse tomato fertilization and gas.The main conclusions obtained are as follows:（1）Water-gas coupled drip irrigation and reduced potassium application can improve soil aeration and enhance the uptake of soil nutrients by tomato.During the whole reproductive period,soil oxygen diffusion rate,soil redox potential and soil respiration rate all reached the maximum in OK2 treatment（combination of water-air coupled drip irrigation and 66%potassium reduction treatment）;at the ripening stage,the minimum values of alkaline nitrogen,fast-acting phosphorus,fast-acting potassium and organic matter content in tomato root zone all appeared in OK2treatment.（2）Water-gas coupled drip irrigation and reduced potassium application could promote tomato growth and improve photosynthetic physiology of tomato leaves as well as inter-root morphology.The maximum fluorescence,maximum photochemical efficiency,potential photochemical efficiency and chlorophyll of tomato leaves were at the seedling stage in the SK2 treatment（combination of normal subsurface drip irrigation and 66%potassium reduction treatment）,flowering and fruiting stage in the OK2 treatment,and at maturity in the OK2 treatment.At maturity,root length,root surface area,root volume,root tip number and root meristem number of tomato were all maximized in the OK2 treatment.（3）Water-gas coupled drip irrigation and reduced potassium application improved tomato biomass,yield and quality.During fruit expansion and ripening,aboveground fresh weight,aboveground dry weight,belowground fresh weight and belowground dry weight of tomatoes reached the maximum in OK2 treatment;the maximum concentration of single fruit quality,yield,soluble solid form,vitamin C and lycopene of tomatoes appeared in OK2 treatment;the maximum number of fruits per plant and soluble sugar content were reached in OK3 treatment;the organic acid content of tomatoes reached the maximum in SK3 treatment（combination of normal subsurface drip irrigation and 33%reduced potassium treatment）.The maximum organic acid content of tomato was reached in the SK3 treatment（combination of normal subsurface drip irrigation and 33%potassium reduction treatment）,and the maximum protein content was reached in the OK4 treatment（combination of water-gas coupled drip irrigation and conventional potassium application treatment）.（4）Water-gas coupled drip irrigation and reduced potassium application improved the uptake and utilization of potassium in tomato.At maturity,the total potassium content and potassium accumulation in leaves,stalks,fruits and roots of tomatoes under water-gas coupled drip irrigation were all maximized in OK2treatment.Among them,the maximum values of potassium fertilizer agronomic utilization,potassium fertilizer bias productivity and potassium utilization efficiency were found in OK2 treatment,the maximum value of potassium physiological efficiency was found in OK1 treatment and the maximum value of potassium utilization efficiency was found in OK3 treatment.A comprehensive analysis of tomato growth physiology,root zone soil environment,yield,quality,potassium uptake and utilization efficiency showed that the water-gas coupled drip irrigation method with 66%potassium reduction(OK2treatment,144 kg·hm^-2)was the optimal water-fertilizer-air coupling mode for greenhouse tomato production management.