Effects Of Different Fertilization Amounts Of Nitrogen,Phosphorus And Potassium On Olive Root Development And Rhizospheric Microenvironment

Nitrogen,phosphorus and potassium in the soil are essential nutrients for plant growth and development,they not only involve in the construction of plant roots and shoots,provide substantial basis for the formation of plant biomass,but also have an important impact on plants rhizospheric microenvironment.Due to the introduction of olives in China is relatively in a short time span and the lack of systematic scientific fertilization theories,olive fertilization can only refer to the fertilization measures of other fruit trees,thus result in lower fertilizer utilization efficiency and deterioration of the soil environment.Therefore,the research and formulation of nutrient control and soil management measures for olives are extremely essential to the development of the olive production.In this study,we used the annual olive seedlings as experimental materials?the variety was“E'Zhi No.8”?,the experiments were designed as follows:six N fertilizer utilization levels labelled as CK,N1,N2,N3,N4,N5?the N utilization amount was 0 g,12 g,24 g,36 g,48 g and 60 g per plant?respectively,and six P fertilizer utilization levels labelled as CK,P1,P2,P3,P4,P5?the P₂O₅ utilization amount was 0 g,15 g,30 g,45 g,60 g and 75 g per plant?respectively,and six K levels utilization levels labelled as CK,K1,K2,K3,K4,K5?the K₂O utilization amount was of 0 g,10 g,20 g,30 g,40 g and 50 g per plant?respectively.To evaluate the effects of different fertilization amounts on olive root development and rhizospheric microenvironment,the olive root growth and development,rhizospheric soil`s physicochemical property,nutrient condition,enzyme activities,microbial number as well as plant biomass indexes under different levels of N,P and K fertilizer utilization amount were carried out.The main conclusions are as follows:?1?The results indicated that,olive growth were inhibited,the plants were short,the root biomass was low and growth and development of olive were slow with insufficient nutrient supplied in soil.Comparing the six N,P and K fertilizer utilization levels,it was the best to promote the olive root physiology,growth and development and rhizospheric microenvironment with 36g N,45g P?P₂O₅?and 20 g K?K₂O?per plant.Utilizing appropriate amounts of N,P and K fertilizers reduced the relative conductivity of the root system,increased the root vigon,root water content and the content of soluble sugar,soluble protein,and proline of the olive root,increased the total root length,root surface area,root volume and total roots number.Reduced the average root diameter,thus optimized the spatial distribution of the root system in the soil and promoted the absorption and utilization of nutrients by the olive root system.The specific performance was that the plant height,stem diameter and the accumulation of dry matter between the shoot and the root system of olive seedings were significantly improved,the ratio of root to shoot was optimized.Compared with the control group,after utilizing 36g N,45g P and 20g K of fertilizer,the olive root activity increased by71.66%,80.06%and 88.08%respectively,soluble sugar content increased by 91.43%,115.15%and 85.00%,root length increased by 126.14%,133.79%and 85.41%,the root surface area increased by 104.71%,114.36%and 105.27%respectively.Among them,the appropriate utilizing amount of N was more conducive to the accumulation of shoot biomass,compared with the control group,the olive shoot dry weight increased by36.35%;the P had the most significant effect on the growth of olive root system,after adding appropriate amount of P,the olive root dry weight increased by 72.48%compared with the control group;the olive root to shoot ratio increased significantly after adding the most appropriate amount of K,which was 41.49%higher than that of the control group,and the promotion effect was the best among the three tested fertilizers.?2?For the rhizospheric microenvironment of olive,the application of N,P and K fertilizer adjusted the soil pH and moisture content,increased the content of nitrogen,phosphorus,potassium and organic matter in the soil,improved the activities of soil urease,invertase,alkaline phosphatase and catalase,increased the number of bacteria and actinomycetes,reduced the number of fungi and increased the bacteria/fungal ratio in soil.After applying N fertilizer,available nitrogen and total nitrogen increased by132.06%and 40.92%,the activity of soil invertase increased by 125.99%respectively,compared with the control group.Compared with the non P utilizing treatment,after the addition of appropriate amount of P fertilizer,the content of available phosphorus and total phosphorus increased by 201.34%and 47.19%,the activities of alkaline phosphatase and catalase increased by 108.82%and 56.92%,the number of actinomycetes increased by 117.06%respectively.Increased the appropriate amount of K fertilizer reduced the pH of the olive rhizospheric soil.The contents of available potassium,total potassium and organic matter in the soil increased by 34.49%,42.56%and 77.85%respectively,compared with the control group;the activity of urease increased by 40.26%,compared with the control group.Comparing the three tested fertilizers,the K fertilizer had the most significant effect on soil microbial quantity.After adding appropriate amount of K fertilizer,the number of soil bacteria increased by 52.14%compared with the control group.While the number of fungi decreased significantly,only 22.53%of the control group,and the ratio of bacteria/fungal was6.75 times of that in the control group.