Effects Of Different Water And Fertilizer Combinations On Yield, Quality And Physiological Characteristics Of Tomato In Greenhouse Under Drip Irrigation

The effects of different water and fertilizer treatments on the growth and physiology of tomato?Yingshidahong?in solar greenhouse under drip irrigation conditon were studied in order to provide theoretical basis for reducing fertilizer application and water-saving cultivation in solar greenhouse.Three irrigation water limits were set,i.e.70%?W₁?,80%?W₂?and 90%?W₃?of the maximum field water holding capacity,respectively.The lavese irrigation water limit was set at 50%of the maximum field water holding capacity.Three levels of N,P and K fertilization were set:low fertiling amout F₁[N?228 kg/hm²?,P₂O₅?132 kg/hm²?,K₂O?300 kg/hm²?],medium fertilizer F₂[N?285 kg/hm²?,P₂O₅?165 kg/hm²?,K₂O?375 kg/hm²?]and high fertiling amount F₃[N?342 kg/hm²?,P₂O₅?198 kg/hm²?,K₂O?450 kg/hm²?].The control group?CK?was treated with traditional water and fertilizer[?342kg/hm² N,198kg/hm²P₂O₅,450kg/hm² K₂O?and flooded with water].The main results are as follows:1.Under the condition of water and fertilizer integration,the fresh weight and dry weight of shoot,fresh weight and dry weight of root and root-shoot ratio of tomato plants were significantly higher than those of traditional water and fertilizer CK except for F₃W₁?high-fertilizer and low-water?;except for F₁W₁?low fat and low water?treatment root activities of other treatments were higher than CK,especially in F₂W₃?middle fertilizer and high water?treatment,and the difference was significant when compared with CK?P<0.05?;The economic and biological yield of tomatoes treated with F₂W₂?middle fertilizer and water?reached the highest,which were 15.4%and 14.12%higher than CK,and the difference was significant with CK.2.The chlorophyll content,Pn,Gs and Tr of tomato leaves reached the maximum under F₂W₂?middle fertilizer water?treatment.Under the condition of water and fertilizer integration,chlorophyll content at the early fruiting stage was higher than CK except for F₁W₂,F₂W₃ and F₃W₃ treatments.At the middle fruiting stage,except F₃W₃treatment,chlorophyll content was higher than CK,and at the later end of the fruiting stage,except for F₁W₃ treatment,chlorophyll content was higher than that of CK.However,the intercellular CO₂ concentration?Ci?reached the maximum under F₂W₃ treatment significantly,and there was no significant difference between F₂W₂treatment and F₂W₃ treatment,but there was significant difference between CK treatment and F₂W₃ treatment.Similarly,the maximum photochemistry rate?Fv/Fm?,actual photochemistry rate?PSII?and non-photochemistry quenching coefficient?NPQ?of tomato leaves under the condition of water and fertilizer integration reached the maximum under the treatment of F₂W₂,and were significantly higher than that of CK.The photochemical quenching coefficient?qP?reached the maximum under CK,but there were no significant differences when compared with F₂W₁?medium fertilizer and low water?,F₁W₂?low fat medium water?,F₂W₃?medium high water?.3.The contents of VC,lycopene and soluble sugar in tomato fruit quality were the highest in F₂W₂?medium water fertilizer?treatment,which increased by 236.6%,81.1%and 102.3%compared with CK,and the difference was significant compared with CK.The increase in the amount increases first and then decreases.Soluble protein reached the maximum under F₂W₃?middle fertilizer and high water?treatment,which was increased by 50.3%compared with CK,but there had no significant difference compared with F₂W₂ treatment and F₂W₃ treatment.The organic acid content reached the maximum?0.342%?under F₃W₁ treatment,which increased by 87.8%compared with CK,and decreased gradually with the increase of irrigation amount.Nitrate content reached 25.51 mg/kg under CK treatment,and increased with the increase of the application of fertilizing amount.4.The irrigation of and fertilization had significant effects on the activities of antioxidant enzymes in tomato leaves at different growth stages.The activities of SOD,POD and CAT reached their highest values under F₂W₂ treatment at all growth stages,and had significant drfferences compared with CK?P<0.05?.Indicated appropriate irrigation was more conducive to the increase of antioxidant enzymes in tomato leaves.The content of MDA in all growth stages was the lowest under F₂W₂ treatment,which was significantly lower than CK.It is suggested that rational irrigation and fertilization could reduce the content of MDA in tomato plants and reduce the damage of stress to plants.The activities of antioxidant enzymes and MDA content in tomato leaves at different growth stages showed significant levels under the interaction of water and fertilizer among each other.5.The activities of nitrogen metabolism-related enzymes in tomato leaves treated with F₂W₂ was higher than those of other treatments,and were significantly higher than those of CK.The interaction of water and fertilizer had significant positive effects on NR,GS,GOGAT,GDH and the content of nitrate nitrogen in all growth stages.The activity of sucrose synthase?SS?in sugar metabolism in tomato leaves reached the highest under F₁W₃?low fertilizer and high water?treatment at all growth stages,but there was no significant difference between F₂W₂ treatment and CK treatment at the middle and late fruiting stages?P<0.05?.The activities of sucrose phosphate synthase?SPS?and neutral invertase?NI?reached their maximum at the initial fruiting stage under F₂W₃?middle fertilizer and high water?treatment,while the activities of the two enzymes reached the maximum at the middle fruiting stage under F₂W₁?middle fertilizer and low water?treatment.The activities of the two enzymes reached the maximum at the end of the fruiting stage under the under medium water fertilizer?F₂W₂?treatment,and there were significant differences,compared with CK.The activity of acid invertase?AI?reached the maximum at the early and middle stages of fruiting under F₂W₃ treatment,and reached the maximum at the later stage of fruiting with medium water fertilizer?F₂W₂?treatment.Comprehensive analysis showed that when the irrigation water limit was80%?W₂?,the total irrigation water amount was 3686.691 m³/hm²,and the fertilization amount was F₂[N?285 kg/hm²?,P₂O₅?165 kg/hm²?,K₂O?375 kg/hm²?].The optimal water and fertilizer treatment of the experiment increased the yield by 15.4%,the fertilizer by 20%,and the water saving by 54.84%compared with the traditional water and fertilizer treatment.