| Long term and large-scale application of chemical fertilizer,especially nitrogen fertilizer,resulted in decreasing yield and quality of banana,acidating banana garden soil and spreading banana wilt,which restricted the development of banana industry.At present,organic nitrogen replacing part of inorganic nitrogen was one of the organic-inorganic combined application technologies to effectively improve nitrogen utilization and soil fertility.Based on this,pot experiment was used to study the application effect of organic nitrogen partially replacing inorganic nitrogen in banana seedling stage and the response of nitrogen reduction,so as to provide theoretical basis for scientific fertilization of banana.Three treatments with organic nitrogen replacing inorganic nitrogen ratios of 10%(CO10),20%(CO20)and 30%(CO30)nitrogen reduction were set up.The pure chemical fertilizer treatment(CF)were added control.The study was to explore the effects of organic nitrogen replacing part of inorganic nitrogen on the growth,photosynthetic characteristics,material accumulation,soil properties and nitrogen fate of banana seedling stage and was to select a suitable organic nitrogen replacement ratio.The main findings are as follows:At the end of the experiment,compared with CF treatment,CO20 and CO30 treatments both could averagely increase the plant height by 11.63%,the new leaf area by15.53% and the total dry matter accumulation by 24.97%;CO30 treatment could increase the stem circumference by 14.86% and the total nitrogen uptake by 15.26%.With the increase of the proportion of organic nitrogen substitution,the net photosynthetic rate(Pn)of banana leaves could increase significantly,the highest of which was CO30 treatment,and higher than CF treatment by 86.12%.Compared with CF treatment,CO20 and CO30 treatments both could averagely increase the leaves transpiration rate(Tr)by 60.46% and the chlorophyll content by 9.80%.Compared with CF treatment,CO10,CO20 and CO30 treatments all could increase the seedling index 23.08%~53.85%,and the highest of which was CO30 treatment.Compared with CF treatment,CO20 and CO30 treatments both could averagely increase the total nitrogen content of soil(TN)by 8.63%,the alkali hydrolyzed nitrogen content of soil(AN)by 26.96%,and CO30 treatment could increase the soil organic matter content by 24.30%.Compared with CF treatment,organic nitrogen replacing part of inorganic nitrogen treatments all could reduce the nitrogen leaching loss rate 23.99%~32.85%,CO20 and CO30 treatments both could averagely increase the nitrogen soil residue rate by 32.50%,and CO30 treatment could increase the crop absorption rate by 19.86%,could reduce the apparent loss rate by 25.94%.Based on this,organic nitrogen replaced 30% of inorganic nitrogen at banana seedling stage is moresuitable replacement ratio.At the end of the experiment,compared with CF treatment,when organic nitrogen replaced 30% of inorganic nitrogen,four treatments with nitrogen reduction ratios of 0%(CO30),10%(CO30-10),20%(CO30-20)and 30%(CO30-30)all could averagely increase the stem circumference by 13.27%,the new leaf area by 21.86%,the Pn of banana leaves by 74.55%,the total dry matter accumulation by 27.14%,and the seedling index by46.15%.Compared with CF treatment,nitrogen reduction ratio within 20% all could averagely increase the Tr by 57.19%,and about the chlorophyll content nitrogen reduction ratio within 20% all showed no significant differences.Compared with CO30 treatment,about the growth,photosynthetic characteristics,material accumulation CO30-20 treatment all showed no significant differences.With the increase of the nitrogen reduction ratio,the total nitrogen uptake could reduce significantly,the highest of which was CO30 treatment,and higher than CF treatment by 14.77%,and between CO30-20 and CF treatment showed no significant differences.Compared with CF treatment,CO30 treatment could increase the TN content of soil,the AN content of soil,the soil organic matter content,and CO30 treatment could increase the AN content of soil by 19.59%.Compared with CF treatment,nitrogen reduction ratio within 30% all could averagely increase the crop absorption rate by 21.62%,the nitrogen soil residue rate by 36.66%,reduce the nitrogen leaching loss rate by 32.85%,and nitrogen reduction ratio within 20% all could averagely reduce the apparent loss rate by 18.71%.Based on this,when organic nitrogen replaced 30% of inorganic nitrogen,nitrogen reduction 20% at banana seedling stage is more suitable nitrogen reduction ratio.In summary,in terms of banana plant growth indicators,soil properties and fertilizer nitrogen fate,organic nitrogen instead of 30% inorganic nitrogen and 20% nitrogen reduction is a more suitable organic-inorganic combination method. |
