Effects Of Different N,P,K Ratios On The Growth Physiology And Soil Fertility Character Of Sterculia Lanceolata

In the pot experiment of "3414" prescription fertilization which using Sterculia Lanceolata seedlings as experimental object,the index fertilization method and a completely randomized block design was conducted with N,P,K three-factor including four levels?pure N content 0,0.9,1.8,2.7g/plant;pure P content 0,1,2,3g/plant;pure K content 0,0.9,1.8,2.7g/ plant?to study the seasonal dynamics of growth and development,physiological characteristics,plant nutrient content and soil properties of S.Lanceolata under different N,P and K ratios,to reveal their correlation,find out the most favorable fertilization conditions for the growth and soil fertility of S.Lanceolata.and in the hope of provide the basis for the cultivation of S.Lanceolata and the rational fertilization in the landscaping.The results showed that:?1?Among the three factors,nitrogen is the main factor affecting the growth index of S.Lanceolata,P fertilizer has the greatest effect on the ratio of stem to root,and K fertilizer has a greater effect on the ratio of height to diameter.Compared with CK,except for treatment 11?N3P2K2?,all fertilization treatments significantly promoted the plant height,ground diameter,leaf area,stem root ratio,biomass and root growth of S.Lanceolata.The plant height increment,ground diameter increment,height diameter ratio,leaf area,stem root ratio,biomass and root index accumulation of treatment 3?N1P2K2?were the largest,and treatment11?N3P2K2?was the worst.From July to August,the height and ground diameter of S.Lanceolata increased the fastest.?2?Fertilization significantly increased the content of soluble sugar?SS?,soluble protein?SP?,nitrate reductase?NR?on June,increased the content of final November soluble protein?SP?,glutamine synthetase?GS?,transpiration rate?TR?,chlorophyll,and decreased the activities of proline?Pro?,malondialdehyde?MDA?,antioxidant enzyme SOD and POD in the two stages;except for treatment 11?N3P2K2?,the activity of final SS,NR and Pn were higher than CK.SS,SP,NR,Pro,POD in the end stage were higher than those in the middle stage,SOD activity in the end stage was lower than that in the middle stage,and MDA content in the two periods were not significantly different.The effects of nitrogen on physiological characteristics were the most significant.Under high nitrogen level,Pro and antioxidant enzyme activities increase,MDA content increases;under the appropriate ratio of nitrogen,phosphorus and potassium,chlorophyll content and photosynthetic efficiency of Adoxophyes viridis are higher,NR and GS activities increase,which is conducive to sugar and protein accumulation,and promotes carbon and nitrogen metabolism of the seedlings.The content of SS,SP,NR,GS,PN,Chla+b is the highest under N1P2K2 treatment.?3?Compared with CK,fertilization increased the plant nutrient content,soil total and available nutrient content,leaf total carbon and soil organic matter.The total nitrogen content of leaves was higher than that of roots,and the total phosphorus and potassium content of roots were higher than that of stems and leaves.With the growth of S.Lanceolata,the total nitrogen,potassium and soil nutrient content of leaves in the final stage were lower than that in the middle stage,and the total phosphorus content of leaves in the final stage was higher than that in the middle stage.The content of total and available N,P and K in the soil was the highest at the level of N3,P3 and K3 respectively,and the lowest at the level of lack the element.High nitrogen fertilizer can improve the nitrogen content of plants and soil,but reduce the total potassium content of leaves and soil;the increase of nitrogen and potassium level can increase the accumulation of soil phosphorus,and the lack of potassium treatment can increase the phosphorus content of roots and leaves;the lack of nitrogen treatment can increase the planting total potassium content of plant,and high nitrogen is unfavorable to the accumulation of potassium.The accumulation of N,P and K in plants was significantly correlated with the physical and chemical properties of soil,but there was no significant interaction effect between elements except that total root P,total leaf phosphorus was positively correlated with total leaf nitrogen and nitrate nitrogen.?4?Fertilization significantly reduced the p H of the soil,increased the activities of invertase,urease and catalase in the middle and final stages of the soil,and soil enzymes in the final stage were higher than those in the middle stage.p H was negatively correlated with carbon and nitrogen content,available potassium and soil enzymes.The effects of three factors on sucrase,urease and catalase activities were K,N and P,respectively.Urease was positively correlated with soil nitrogen,but there was no correlation among the three soil enzymes.?5?DRIS nutritional diagnosis showed that under the treatment of lack an element,the plant needs more of this element,which has a synergistic effect on the absorption of the other two factors.With the increase of the concentration of one element,the demand for the corresponding elements of S.Lanceolata decreased or exceeded,and the demand for the other two factors increased.High N and P fertilizer can increase the accumulation of nitrogen,and low nitrogen has a significant synergistic effect on K absorption The results showed that the nutrient balance of N1P2K2 was the best,which was consistent with the comprehensive performance of S.Lanceolata seedlings.?6?Proper fertilization can improve photosynthesis,increase plant nutrients and soil fertility,and promote the growth and development of S.Lanceolata.The analysis of seedling quality and membership function showed that treatment 3?N1P2K2?had the highest ranking,and had the best effect on promoting the growth and maintaining the normal physiological metabolism of S.Lanceolata,and excessive N application will cause inhibition effect.In greenhouse cultivation of S.Lanceolata,N: 0.9g/plant,P₂O₅: 2g/plant,K₂O: 1.8g/plant?pure N,P,K content?were the most favorable for the growth and development of seedlings.