| Excessive application of chemical fertilizer and low utilization rate are important problems in vegetable production,which seriously affect the quality of soil environment and the sustainable production of vegetables.In this study,"green shoots" was used as the test material,and five treatments were set up,including no fertilization(CK),conventional fertilization(CK1,local farmers’ conventional fertilization),conventional fertilizer reduced fertilization(T1),slow-release fertilizer was reduced(T2),slow-release fertilizer common fertilization(T3).T1 and T2 were reduced by 35.2% compared with the total fertilization amount of regular fertilization.In order to provide a reasonable fertilization model for local asparagus lettuce production,the effects of slow-release fertilizer instead of common fertilizer on growth physiology,nutrient utilization,yield,quality,soil nutrients and related enzyme activities of lettuce were studied.The main results are as follows:1.Compared with CK1 treatment,the plant height,stem diameter,stem length,root length and root activity of asparagus lettuce treated with T2 and T3 were significantly improved,while the stem diameter and stem length of asparagus lettuce treated with T1 were significantly increased,the stem diameter and stem length of asparagus lettuce treated with T2 and T3 were increased by 20.9%,15.7% and 14.0%,10.4% respectively.Compared with CK1 treatment,the contents of chlorophyll a + b and carotenoid in T2 treatment increased by23.0% and 18.5% respectively.Nitrate reductase activity(NR)of asparagus lettuce leaves treated with T2 was significantly higher than that of other treatments.2.Compared with CK1 treatment,the yield of asparagus lettuce in T1,T2 and T3 treatment was significantly increased,among which,T2 treatment had the highest yield,which was 12.4% higher than CK1 treatment.There was no significant difference between T1 and T2.The total amount of dry matter accumulation of asparagus lettuce was T2 > T3 >T1 > CK > CK1,and there was a significant difference among the treatments.The total amount of dry matter accumulation of T2 was 22.6% higher than that of CK1.3.Compared with CK1 treatment,T1,T2 and T3 treatment can significantly improve the absorption of nitrogen,phosphorus,potassium and fertilizer utilization rate of asparagus lettuce.The absorption capacity of nitrogen,phosphorus and potassium was T2 > T3 > T1 >CK1,and the utilization ratio of nitrogen,phosphorus and potassium was T2 > T1 > T3 >CK1.Compared with CK1,the absorption of nitrogen,phosphorus and potassium in T2 treatment increased by 116.4%,90.3% and 13.1% respectively,and the absorption and utilization of nitrogen,phosphorus and potassium increased by 16.0,5.5 and 23.6 percentage points respectively.4.Compared with CK1,T2 and T3 can significantly asparagus reduce the nitrate content of asparagus lettuce stem and increase the content of soluble protein,Vc,soluble sugar and free amino acid.Among them,T2 can reduce the nitrate content of asparagus lettuce stem by17.6%,soluble protein,Vc and soluble sugar by 7.8%,3.2% and 78.5%,T3 can reduce the nitrate content of lettuce stem by 6.9%,soluble protein and soluble amino acid by 7.8%,3.2% and 78.5%,respectively The contents of sexual sugar,Vc and free amino acids increased by 22.9%,13.1%,45.1% and 27.0%,respectively.Compared with CK1 treatment,T1 treatment significantly reduced nitrate content and increased Vc content in asparagus lettuce stem,in which nitrate decreased by 12.2% and Vc increased by 37.6%.5.When asparagus lettuce was harvested,the contents of available N,available P and available K in the soil of each fertilization treatment were T3 > T2 > CK1 > T1.Compared with the CK1 treatment,the contents of alkali hydrolyzed n,available P and available K in T2 and T3 treatment were higher than those in CK1,and the contents of available N,available P and available K in T1 treatment were significantly lower than those in CK1;the contents of urease(Ure),invertase(INV)and neutral phosphatase(SNP)in T2 and T3 treatment were higher than in CK1 treatment,T2 reached a significant level.In conclusion,using slow-release fertilizer replacing general fertilizer and reducing the amount of fertilizer by 35.2% can improve the output of asparagus lettuce,the quality of products,the utilization rate of fertilizer,the content of soil available nutrients and the activity of related enzymes,which can be used as a reference for the production and fertilization of asparagus lettuce in local greenhouse. |
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