| As an organic fertilizer(biogas slurry)that has attracted much attention in recent years,in addition to its own characteristics of containing a large number of nutrients that promote crop growth and development and improving soil environmental conditions when applied on farmland,the key point is that it can be well dissolved in water and can be applied together to achieve the effect of "adjusting fertilizer with water and promoting water with fertilizer".Since tomatoes have different water and fertilizer requirements at different reproductive stages,if the same water/biogas slurry integrated volume ratios are applied throughout the crop reproductive period,water and nutrient surpluses will occur at some growth sta ges and deficits at some crop growth stages,leading to problems such as tomato water use efficiency,lower crop yields and poorer quality of the soil nutrient environment.Based on this,this study introduced the theory of deficit-regulating irrigation on the basis of integrated water/biogas slurry cavity irrigation,and applied different levels of water/biogas slurry homeostasis treatments at three tomato fertility stages(seedling,flowering and fruiting,and fruit ripening),i.e.,high water and low fer tilizer level(A: irrigation coefficient 0.85,biogas slurry concentration 11.1%),medium water and fertilizer level(B: irrigation coefficient 0.75,biogas slurry concentration 14.3%),and low water and high fertilizer level(C: irrigation coefficient 0.6 5,biogas slurry concentration 20.0%).The response patterns of tomato physiology and ecology,yield,quality and soil nutrient indicators under different water/biogas slurry homeostasis treatments were used to provide a scientific and theoretical basis fo r water and fertilizer management of greenhouse tomatoes at different fertility stages.The main conclusions are as follows:(1)The physiological and ecological indicators of tomato were significantly affected by the application of different integrated water/biogas slurry irrigation treatments at different fertility stages.The maximum values of tomato plant height,stem thickness,leaf area and dry matter mass of above and below ground parts were reached at T8(medium water fertilizer level B applied at all three fertility stages)treatment in both seasons of the experiment.(2)The water use efficiency and yield of tomatoes were a ffected by applying different water/biogas slurry integrated deficit regulation irrigation treatments at different fertility stages.The pattern of water use efficiency of tomato in both seasons was T9>T4>T8>T6>T2>T5>T1>T3>T7>T0.The highest water use effi ciency of0.173kg/L and 0.171kg/L was observed in T9(low water and high fertilizer level C applied in all three fertility stages)treatment,which was 37.3% and 47.3% higher than that in T7(high water and low fertilizer level A applied in all three ferti lity stages)and T0(pure water with irrigation factor 0.85 applied in all three fertility stages)treatments.The water use efficiency increased by 37.3%,47.4% and 40.7%,50.0% compared to T7(pure water with irrigation factor 0.85 applied in all three fertility periods)and T0(pure water with irrigation factor 0.85 applied in all three fertility periods)treatments,i.e.,T9 treatment was the best in improving water use efficiency of tomato;tomato yield was the highest in both seasons under T8(medium water fertilizer level B applied in all three fertility periods)treatment with 5.612 kg and 5.034 kg,respectively.(3)The quality of tomatoes was significantly(P<0.05)affected by the application of different water/biogas slurry integrated deficit irrigation treatments at different fertility stages.The maximum values of fruit shape ratio,sugar-acid ratio,soluble solids,vitamin C,soluble protein and fruit water content were reached at T8(medium water fertilizer level B at all three fertility stages),soluble sugar,titratable acid and hardness at T9(low water and high fertilizer level C at all three fertility stages),T4(medium water fertilizer level B at seedling stage,low water and high fertilizer level C at flowering and fruiting stage and high water and low fertilizer level C at fruit ripening stage,respectively)in both seasons.The objective and subjective weight values of each single quality index of tomato were determined by the entropy weighting method and hierarchical analysis method,com bined with the game-theoretic combination weighting method to obtain their combined weight values,and finally,using the TOPSIS method,we obtained the following patterns of comprehensive quality evaluation values of tomatoes under different treatments:T8>T4>T9>T6>T1>T3>T2>T7>T5>T0,T8>T4>T6>T9>T3>T7>T2>T1>T5>T0,and the ranking of the overall quality scores of tomatoes under T8 treatment were all the highest at 0.7714 and 0.6630,i.e.the T8 treatment tomatoes with medium water fertilizer level B applied throughout the three tomato reproductive periods had the highest overall quality ratings.In this study,yield,water use efficiency and overall quality of tomatoes were used as evaluation indicators for the overall benefit of tomatoes,and the overall benefit evaluation values of tomatoes under different treatments were obtained by the combined evaluation method,and the best overall benefit of tomatoes was obtained under the T8 treatment.(4)The soil nutrient environment in the root zone of tomato was s ignificantly affected by the application of different levels of water/biogas slurry integrated deficit treatment at different tomato fertility stages.Soil p H was reduced by applying different levels of water/biogas slurry treatments at different fertility stages of tomatoes;the contents of ammonium N,nitrate N,total N,organic carbon and organic matter in the soil of tomato root zone basically showed a pattern of increasing from0 to 20 cm and decreasing from 20 to 60 cm at the depth of 0-60 cm,reaching a maximum at the depth of 20 cm.The T8 treatment at level B had the best effect in increasing the content of ammonium N,nitrate N,total N,organic carbon and organic matter in the soil. |
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