Effects Of Irrigation Amount And Fertilizer Types On Water And Fertilizer Utilization And Root-zone Environment Of Greenhouse Tomato

Excessive irrigation and fertilization in greenhouse vegetable cultivation can easily lead to waste of water and fertilizer resources,soil compaction,declined soil fertility,crop quality reduction and environmental pollution,etc.Studying the effects of reduced chemical fertilizers application,replacing chemical fertilizer with organic fertilizer,and combined application of organic and inorganic fertilizers on greenhouse crop yield and quality,water and nutrient utilization and soil environment under water-saving irrigation condition is the key to the current green development of facility agriculture in China,which has important theoretical and practical significance for realizing high-quality and efficient production of greenhouse crops and sustainable agricultural development.In this study,four-season experiment was carried out on tomato in greenhouse of Guanzhong region under drip fertigation.The experiment set up three irrigation amounts,including 100%ET_c?W1?,75%ET_c?W2?and 50%ET_c?W3?;and four fertilizer types,including chicken manures for basal application and chemical fertilizers for topdressing?CC?,soluble organic fertilizers for topdressing?SO?,soluble chemical fertilizers for topdressing?SC?,both soluble organic and chemical fertilizers for topdressing?SOSC?.A total of 13 treatments were included with the W1 and no fertilizer application?CK?.The effects of various water and fertilizer supplies on growth and physiological characteristics,water consumption,yield and fruit quality,nutrient uptake and translocation,soil environment,water and fertilizer utilization efficiency and economic benefits of greenhouse tomato were explored.The main results are as follows:?1?The effects of different water and fertilizer modes on tomato growth,photosynthetic and water consumption characteristics were revealedDifferent water and fertilizer supply modes had significant effects on stem diameter,leaf area,dry matter and leaf SPAD value.Suitable irrigation amount improved leaf area,dry matter and leaf SPAD value of greenhouse tomato.Compared with autumn,the temperature in spring was more suitable to improve plant height and dry matter of tomato.Under the same irrigation condition,SOSC treatment significantly improved plant height,dry matter and leaf SPAD value of greenhouse tomato.The sufficient nutrients and water supply of SC treatment in spring under W1 led to excessive growth,which inhibited the growth and nutrient uptake of tomato fruit in the later stage and obtained the lowest leaf SPAD value compared with other fertilizer treatments.Different water and fertilizer supply modes had significant effects on water consumption characteristics of greenhouse tomato?P<0.05?.At the seedling stage and the blooming and setting stage,SC and SOSC improved water consumption,and CC treatment had the smallest.The SO and SOSC had significantly greater water consumption than SC at the fruit expanding stage,except in spring 2017?P<0.05?.The water consumption at the harvest stage of SO and SOSC were still significantly greater than that of SC treatment?P<0.05?.Then,the water consumption rate of each growth stage was the highest under SOSC.The CC under W2condition had lower water consumption rate of the seedling stage,blooming and setting stage as well as fruit expanding stage.The SC had higher water consumption rate at blooming and setting stage under W1,lower one at harvest stage under W2,and higher water consumption modulus of the seedling stage as well as blooming and setting stage.?2?The responses of nutrient uptake of tomato organs to different water and fertilizer supply modes were exploredAs irrigation decreased,the amount of nitrogen?N?,phosphorus?P?,and potassium?K?absorbed by plant reduced.SOSC effectively promoted the N absorption in each organ,and SO increased N uptake of fruit and root.SOSC and SO improved the P and K uptake of each organ and total absorption.The total P uptake of SO was smaller than that of SOSC under the W1condition in spring and the W3 condition in spring 2017.The SC was significantly greater total P uptake than CC under the W1 and W2 conditions after spring 2016 season?P<0.05?.The SC had significantly larger plant K uptake amount than the CC under the W3 condition in autumn2015?P<0.05?.?3?The effects of different water and fertilizer modes on soil nutrients and microbial environment was investigatedThe soil NO₃^--N residue under SC was higher under W1 condition in autumn and W3 in spring,while it was greater than other fertilizer treatments under W2 condition.The SOSC had smaller soil NO₃^--N residue below 30 cm soil layer under W1 and W2 conditions.Moreover,the peak of soil available P accumulation in SC moved down to 30 cm soil layer with time,and there was a high residual amount in the surface soil under W3 condition.Soil available P residue in CC was low in the surface soil and high in the deep soil.Additionally,the accumulation of total available K in 0-60 cm soil was increased in SC treatment.The SO and SC improved accumulation of total available K under W1 condition,and the accumulation amount under W2 and W3 treatment became smaller.Soil organic matter content decreased in the30-40 cm soil layer under W1 condition and in the 0-10 cm soil layer under W3 condition.The SC maintained and even reduced the content of soil organic matter.The CC,SO,and SOSC had the potential to improve soil organic matter storage over time.All of the CC,SO and SOSC increased the number of soil bacteria,actinomycetes and fungi as well as soil enzyme activity,but the SC treatment showed the opposite trend.Using the principal component analysis to comprehensively evaluate the effects of treatments on soil environment,it was concluded that the CC and SOSC treatments affected soil environment negatively under the W3 condition in spring.Under different growing seasons and irrigation amounts,the order of fertilizer types that had positive impacts on the soil environment was SOSC>SO>CC>SC.?4?The effects of different water and fertilizer supply modes on the yield and quality of greenhouse tomato were analyzedThe total yield and economic yield of tomato were positively correlated with the amount of irrigation.As the irrigation amount decreased,the differences in yield under various fertilizer types treatments became smaller.The W2 reduced the unmarketable yield,followed by W1 and W3.The SOSC increased average fruit weight and fruit number per plant,and improved yield significantly?P<0.05?.The CC and SC reduced average fruit weight and fruit number per plant without significant differences?P>0.05?.Water deficit reduced the differences in yield between the CC and SC.The content of soluble solids,vitamin C and soluble sugar increased as water supply decreased.Organic fertilizer addition improved fruit quality and reduced fruit nitrate content.The CC increased soluble sugar and titratable acid content,while the SC improved sugar acid ratio and nitrate.Compared with CK,fertilization increased the soluble solids content of the fruit,but there were no significant differences between fertilizer type treatments?P>0.05?.?5?The best water and fertilizer supply modes which are suitable for local high-efficiency and high-quality greenhouse tomato production were determinedWater use efficiency of tomato decreased with the increase of irrigation amount.The largest water use efficiency was obtained in SOSC.The W1 and W2 promoted the SC to obtain higher water use efficiency.The CC increased water use efficiency only under W3 treatment.There were significant differences in nitrogen recovery efficiency among the four types of fertilizer treatments except in autumn 2015,which were SOSC>SO>SC>CC?P<0.05?.The SOSC achieved greater nitrogen agronomic efficiency compared to other fertilizer types treatments in autumn 2016 and spring 2017.The W1 harvested more fruits weighing less than100 g.The W2 improved gross benefits of middle and large fruits.The SOSC improved gross profit of each fruit size and total net benefit compared with different fertilizer types treatments.The CC decreased economic benefits under W1 and W2 conditions.Additionally,the comprehensive evaluation using the principal component analysis showed that the W2SOSC treatment was the first to be recommended in autumn,and the first comprehensive ranking in spring was W1SOSC.