| In order to improve the situations of the excessive application of chemical fertilizers which lead to diminished vegetable quality,low fertilizer utilization rate,and environmental pollution.A field experiment was conducted using Asparagus lettuce as material to study the effects of different fertilizer combinations on yield,quality,photosynthesis,dry matter accumulation,nutrient absorption,fertilizer utilization,soil physical-chemical properties and soil microbial quantity,which could provide the scientific basis for reasonable fertilization of Asparagus lettuce.The experiment used a completely randomized block design to set a conventional fertilization(CF),20%reduction of conventional fertilization(F1)and 30%reduction of conventional fertilization(F2)and combined with 200 kg/667 m~2(B1)or 400kg/667 m~2(B2)bio-organic fertilizer,meanwhile,non-fertilization(CK)and conventional fertilization(CF)were set as two control treatments.The main research results were as follows:1.The combined application of bio-fertilizer(200,400 kg/667 m~2)with chemical fertilizer(-20%,-30%of conventional fertilization)treatments increased the plant height,stem height and stem diameter in different degrees of asparagus lettuce compared with CF,among them,these indexes of F1B2 reached maximum.The content of photosynthetic pigments in F1B2 treatment increased by 17.32%and1.74%compared to CK and CF,respectively.In addition,the net photosynthetic rate in asparagus lettuce treated with F1B2 treatment reached the highest,with increasing degree ranging from 6.90%~49.35%.Compared with CF treatment,the accumulation of dry matter in roots,stems and leaves of F1B2 treatment were increased by 5.74%,22.19%and 17.82%.2.The yield increased by biological organic fertilizer under different combinations,and 400 kg/667 m~2(F1B2 and F2B2)treatments were the most effective treatments.Compared with CF,the yield of F1B1,F1B2,F2B1 and F2B2increased by 4.76%,15.31%,4.11%and 11.06%,respectively.And the yield of F1B2was the highest,which was 8277.00 kg/667 m~2.The contents of nitrate in stem and leaf were decreased by reducing the chemical fertilizer.Additionally,the contents of soluble protein,soluble sugar and vitamin C were increased by applying biological organic fertilizer.Under each treatment,400 kg/667 m~2 biological organic fertilizer led higher content of vitamin C compared with the application of 200 kg/667 m~2biological organic fertilizer.3.The application of 100%conventional fertilizer exceeded the fertilizer supply,and the balance between supply and demand of fertilization was destroyed,which leads to the waste of fertilizer.The contribution rate of fertilizer was significantly improved by combined application of bio-fertilizer with chemical fertilizer.Compared with the treatment CF,the accumulation of N,P and K nutrients of F1B2 treatment increased by 128.96%,113.23%and 23.10%,respectively.The reduction of fertilizer combination with bio-organic fertilizer significantly improved the recovery efficiency,agronomic efficiency and partial factor productivity of elements of N,P and K.Besides,the dependent rates of N,P,K of CF reached the highest.4.The application of bio-organic fertilizer significantly increased soil nutrient content.Compared with CF,the contents of soil organic matter,total N,P,K and alkaline N,available P and available K were increased by 71.65%,84.53%,75.41%,19.94%,75.90%,17.06%and 24.35%in the treatment F1B2,and were increased by58.51%,70.17%,72.13%,9.28%,42.94%,13.48%and 11.42%in the treatment F2B2,respectively.5.The combination of chemical fertilizer and bio-organic fertilizer increased the number of bacteria and actinomycetes in the soil of asparagus lettuce,but inhibited the growth of fungi.The number of bacteria increased with the increase of the amount of bio-organic fertilizer,and the number of actinomycetes increased with the decrease of chemical fertilizer,but the number of fungi decreased with the increase bio-organic fertilizer.Compared with CF,the number of aerobic azotobacter,anaerobic azotobacter,nitrifying bacteria and denitrifying bacteria were increased by 1.36 times,6.10 times,47.50 times and 23.76 times in the treatment F1B2,respectively.The number of bacteria was significantly and positively correlated with the contents of organic matter,alkaline N,available P and total N content.And there was a significant and positive correlation between the number of actinomycetes and the content of total P.The number of azotobacters and nitrogen transformational bacteria showed a significant or extremely significant positive correlation with the contents of alkaline N and total N content.According to the results of principal component analysis and comprehensive scores,the soil quality under different fertilization treatments with the following sequence of F1B2,F2B2,F1B1,F2B1,CF and CK.To sum up,partially replacing chemical fertilizer with bio-organic fertilizer improved soil physical and chemical properties by improving the content of soil nutrient and regulating the structure of soil microbial community,thereby enhanced the photosynthetic ability of asparagus lettuce leaves,increased the nutrient accumulation and fertilizer utilization rate,and finally,increase production and improved the quality of asparagus lettuce.In summary,the partial substitution of chemical fertilizer with bio-organic fertilizer had good effects on the nutrient accumulation of asparagus lettuce,and could improve the fertilizer utilization efficiency and soil fertility.The F1B2 treatment was the optional treatment in the research,which could provide good fertilization mode to promote rational use of fertilizer resources and improves soil environment. |
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