Characteristics Of Soil Phosphorus Pool In Apple Orchard And Effects Of Soil Phosphorus Content And Phosphorus Sources On Phosphorus Absorption In Apple

Phosphorus is an indispensable element in the process of growth and yield formation of apple.The suitable phosphorus content in soil is the basis of high quality and high yield of apple.However,phosphorus is easily fixed in soil and easy to bring about surplus of phosphorus,thus bring environmental risks.Therefore,confirming the characteristics of the current soil phosphorus pool in apple orchards and the biological basis for the efficient use of phosphorus is important to the efficient use of phosphorus in apple orchards.Therefore,through using the large sample survey,this study analyzed the characteristics of soil phosphorus pools in apple orchards which have different planting years.Using M9T337 and M26 as tested materials,we studied the effects on their growth and phosphorus absorption by testing the soil with different phosphorus contents and examining the formation of phosphorus.The major result is as follows:1.Study on characteristics of soil phosphate pools in apple orchards in Yantai:From September 11 to September 14 in 2017,Yantai City,Shandong Province,the major apple producing each city?Qixia,Penglai,Muping,Zhaoyuan,Laiyang?for the study area,we respectively selected?5 years,6¹0 years,11¹5 years,16²0 and>20 years of apple orchards to survey and sample,which is a total of 100 samples.The results showed that,with the increase of planting years,the content of total phosphorus and available phosphorus in apple orchard soils increased significantly,and the content of total phosphorus and available phosphorus in surface soil was significantly higher than that in other soil layers;the amount of phosphorus surplus in apple orchard was detected up to 301.96⁴88.20kg·hm^-2,with an average phosphorus surplus of 416.28 kg·hm^-2,of which 6¹0 years of the tree in apple orchards are the highest(488.20 kg·hm^-2);0⁶0 cm soil layer of apple orchards in Jiaodong apple producing area has a phosphorus storage up to 4.257⁶.163 t·hm^-2.It is obvious that there is a huge potential for phosphorus reduction in apple orchards,and activating the soil phosphate pool is one of the important ways to achieve phosphorus reduction.2.Effects of soils with different phosphorus levels on seedling growth and phosphorus uptake of apple dwarfing rootstock M9T337:Provided no phosphorus and phosphorus pot experiment,a total of six treatments,respectively:?1?a low phosphorus soil without phosphorus?L?,?2?a low phosphorus soil phosphorus?L+P?,?3?Phosphorus Soils were not treated with phosphorus?M?,?4?medium-phosphorus soils were treated with phosphorus?M+P?,?5?high-phosphorus soils were not fertilized?H?,and?6?high-phosphorus soils were fertilized?H+P?.In the condition of low-phosphorus soil?L?and medium-phosphorus soil?M?,the biomass and root/shoot ratios were greatly improved by applying phosphorus compared to without applying phosphorus,but under high phosphorus soil?H?conditions,there was no significant difference in the growth of apple seedlings with or without the application of phosphorus.Under the conditions of low-phosphorus soil?L?and medium-phosphorus soil?M?,applying P fertilizer significantly increased root length,total surface area,and root tip number,while in high-phosphorus soil?H?,application of P fertilizer inhibited root growth.With or without applying P fertilizer,the activities of acid phosphatase in rhizosphere soil were all manifested as H>M>L,and the activity of acid phosphatase in rhizosphere soil after treatment was lower than that without P treatment.The soil?M?is the most obvious,reduced by 10%.Under the conditions of low-phosphorus soil?L?and medium-phosphorus?M?,application of P fertilizer significantly increased the plant absorption of phosphorus.Under high P,P application inhibited the absorption of P.The apparent phosphorus utilization rate of P fertilizer was M+P>L+P>H+P.Under medium phosphorus level,the apparent phosphorus utilization rate of fertilizer was 15.27%,which was significantly higher than other treatments.3.Effects of different phosphorus sources on growth,phosphorus uptake and rhizosphere soil properties of apple rootstocks:M9T337 and M26 seedlings were used as study materials,with no application of phosphorus?CK?,inorganic phosphorus source?Pi?,and organic phosphorus source?Po?and application of mixed phosphorus source treatment?Pi+Po?.The results showed that dry matter quality,phosphorus accumulation,phosphorus utilization efficiency and root morphology were all significantly higher than M9T337 under all treatments.Dry matter weight,phosphorus accumulation,phosphorus use efficiency,and root morphology of the two rootstocks were all demonstrated with the dealt with Pi being the largest,followed by Pi+Po,and the dealt with Po being the smallest,which was significantly higher than the CK.The activity of acid phosphatase in the rhizosphere was highest in Pp treatment;M9T337 and M26 were 3.91 and 4.23 mg·?g·h?^-1;Pi+Po was the second;Pi was the lowest,74%and 55%of the Po treatment respectively.