| Greenhouse cultivation has become the main form of vegetable production in northern China.In order to pursue high profits,excessive fertilization and irrigation have become a common phenomenon.This not only causes the decrease of vegetable yield and quality and waste of water and fertilizer resources,but also causes the potential groundwater pollution and other harm by the infiltration of excess water and fertilizer into the deep soil by gravity.Meanwhile,the strong trend of climate aridification in north China leads to serious overexploitation of groundwater,continuous degradation of groundwater system and prominent contradiction between supply and demand of water resources,which seriously restricts the development of facility agriculture.Therefore,optimizing fertilization and irrigation is crucial for the sustainable development of facility agriculture to reduce waste of water and fertilizer resources,improve water and fertilizer productivity,and ensure vegetable yield and quality.As the most widely planted vegetable in facility cultivation in my country,tomato is very sensitive to changes in soil moisture,and has become a model crop for plant physiology and biochemical experiments.In this study,greenhouse tomato was taken as the research object,and the effects of fertilization,irrigation and coupling of irrigation and fertilizer on tomato yield,quality and soil environment were explored by applying controlled release fertilizer with different ratio and dosage under different irrigation amount.The main results are as follows:(1)Effects of different irrigation and controlled release potassium chloride application amount on tomato yield,quality and water-fertilizer use efficiency were determined.Under the same application rate of controlled release potassium chloride(CRK),the average yield and potassium use efficiency of tomato in the treatment with 20%reduced irrigation amount increased by 5.3%-10.0%and 4.9-6.9 percentage points,respectively,compared with the treatment with conventional irrigation amount and 40%reduced irrigation amount.Under the same irrigation amount,the average yield and water use efficiency of tomato under CRK reduction of 20%increased by 5.3%-10.4%and 6.5%-11.5%,respectively,compared with other CRK application treatments.Compared with other K application treatments,the average yield and vitamin C content increased by 8.0%-23.7%and 8.9%-28.3%,respectively.Soluble sugar content increased by 2.3%-25.3%on average.Soluble solid content increased by 3.5%-15.5%on average;this treatment increased soil available potassium supply during tomato growth period,decreased H2O2 and malondialdehyde content,and increased leaf and root auxin and resistance.The content of oxidase reduces the damage of lipid peroxidation when satisfying the absorption of potassium by the root system,and provides a guarantee for the improvement of tomato yield and quality.(2)Effects of controlled release potassium chloride on soil bacterial community structure and metabolites under different irrigation amounts were determined.The 16S r DNA gene copy number of soil bacteria increased by 4.2%and 15.7%in controlled release potassium chloride treatment compared with normal potassium chloride treatment under sufficient and insufficient soil water conditions,respectively.Application of CRK significantly increased the relative abundance of Proteobacteria,Betaproteobacteriales and Burkholderiaceae under the condition of 40%reduction in irrigation amount.According to soil metabonomics analysis,CRK application significantly regulated N-glycan biosynthesis,atrazine degradation,retinol metabolism,cutin,suberine and wax biosynthesis,and sphingolipid metabolism.In addition,regulation of fatty acid metabolic pathways by CRK can improve the drought resistance of cells by preventing lipid peroxidation and maintaining cell membrane integrity.The co-occurrence network analysis showed that the application of CRK under deficient irrigation conditions formed a more complex co-occurrence network and contained more positively correlated bacterial groups,which significantly improved the ability of soil bacteria to resist drought stress.(3)Effects of different controlled release potassium chloride and potassium chloride mixing ratios on tomato yield,quality and water-fertilizer use efficiency under different irrigation amount were clarified.In 2020-2021,the tomato yield and quality increased firstly and then decreased with the increase of irrigation amount and CRK mixing ratio.In the same irrigation level,compared with the conventional CRK application and 60%CRK mixed with40%potassium chloride(KCl)application,the average yield,water use efficiency and potassium use efficiency increased by 2.9%-6.4%,3.2%-6.9%and 6.9-11.7 percentage points,respectively,and the tomato fruit quality was also improved by 80%CRK and 20%KCl application.Under the same mixing ratio of CRK and KCl,the average yield and potassium use efficiency in two growing seasons were increased by 3.1%-6.2%and 6.5-10.2 percentage points respectively under the 20%reduced irrigation amount treatment compared with other treatments.The results showed that the average yield and potassium use efficiency increased by 4.6%-18.9%and 11.5-34.2 percentage points respectively,and vitamin C content of fruit increased by 9.3%-25.3%under the condition of 20%reduction of irrigation amount.The soluble sugar content in fruits increased by 10.2%-20.0%on average,and the rubisco activity and osmotic regulatory substance content in leaves at key growth stages were improved,cytokinin and gibberellin in roots and leaves were increased,malondialdehyde and hydrogen peroxide contents were decreased,and finally photosynthetic rate was increased and organic matter accumulation was promoted.(4)Effects of reduced application of controlled release mixed nitrogen fertilizer on tomato growth and soil nitrogen supply under appropriate irrigation amount were determined.Compared with the conventional fertilization treatment,the yield and net income increased firstly and then decreased with the increase of the blending ratio of controlled release urea.The treatment with the mixing ratio of controlled release urea to common urea of 7?3 was the best,and the yield increased 9.2%-25.2%,4.6%-15.0%and 1.9%-7.3%,respectively,compared with conventional fertilization,controlled release urea to common urea of 4?6 and full controlled release fertilizer.Meanwhile,net income increased by 3.7-33.6%,5.9-19.1%and 2.5-9.6%,respectively.The yield and net profit of the treatment with the ratio of controlled release urea to conventional urea of 7?3 and 15%reduction of nitrogen fertilizer were the highest,which were 128908 kg hm-2 and 310817-yuan hm-2,respectively;and the treatment had obvious advantages in improving fruit quality and enhancing soil nitrogen supply.The interactive effect of controlled release fertilizer,controlled release fertilizer mixed with conventional fertilizer and irrigation level made the characteristics of fertilizer nutrient release match the characteristics of tomato demand for nutrients,which not only improved the yield and quality,but also improved the water-fertilizer use efficiency and saved water and fertilizer resources.The results provided technical support for improving the yield,quality and water and fertilizer use efficiency of greenhouse tomato,and theoretical guidance for fertilization and irrigation technology of greenhouse tomato. |
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