Calcium Forms In Apple Root Zone Soil And Their Effects On Root Growth And Development

Calcium is a necessary element in plants,which can reduce fruit quality and fruit resistance,but the total calcium content in many orchard soil with fruit calcium deficiency symptoms is not low.Calcium exists in various forms in soil,and the total calcium content of soil can only reflect the potential of soil supply plant calcium,and it is difficult to reflect the true calcium supply capacity and bioavailability of calcium.The bioavailability of calcium is closely related to its form in soil,and the form of calcium depends on its environment.Rhizosphere is a micro environment in soil which is obviously affected by plant root growth and absorption activities.Different micro environment will change the form,distribution and biological effectiveness of calcium,and also affect the migration and transformation of soil calcium and the absorption and utilization of calcium by plant roots.Rootstock and soil management are important factors affecting the micro environment.In this study,the 8-year Red Fuji apple trees with rootstocks of Chistock#1,SH40,M9,M26 and Begonia octagonus were selected as the main factors.The results showed that the 8-year-old Red Fuji apple orchard was used to investigate the physical and chemical properties of Rhizosphere and non rhizosphere soil,calcium element morphology and content.Meanwhile,the effects of calcium morphology on plant growth and development were studied by adding citric acid.The results show that:1.The nutrient content of the five rootstock grafted apple rhizosphere soil and non rhizosphere soil is similar.The organic matter,alkali nitrogen,available phosphorus and available potassium in rhizosphere soil are higher than those of non rhizosphere soil,and the p H value of rhizosphere soil is lower than that of non rhizosphere soil;the organic matter,alkali nitrogen,available phosphorus and available potassium of apple rhizosphere and non rhizosphere soil with M26 as rootstock are the highest,and the most important ones are SH40low.The p H of rhizosphere Soil and non rhizosphere soil with M26 as rootstock was the lowest,while that of SH40 was the highest,while that of non rhizosphere soil with begonia octagonus as rootstock was the highest.2.The order of the content of calcium in the root area of apple tree grafted by five rootstocks is as follows:residual calcium>exchangeable calcium>acid soluble calcium>water soluble calcium>organic binding calcium;the content of water soluble calcium,exchangeable calcium,acid soluble calcium and organic binding calcium in the rhizosphere and non rhizosphere soil of apple rootstock with M26 as rootstock is the highest,and the content of water soluble calcium in the rooting and non rhizosphere soil is SH40,and the content of water soluble calcium is the lowest,and the content of water soluble calcium in the rootstock and non rhizosphere soil is the lowest,and the content of water soluble calcium in the rooting and non rhizosphere The content of exchangeable calcium and organic bound calcium in rhizosphere and non rhizosphere soil of begonia was the lowest.3.The soil organic matter,alkali nitrogen,available phosphorus and available potassium in the rhizosphere soil of apple under different ground management were higher than that of non rhizosphere soil,and the p H value of rhizosphere soil was lower than that of non rhizosphere soil;the content of alkali solution nitrogen,available phosphorus,available potassium and p H value of apple root area under mulching were significantly higher than that of pure and grass,while the organic matter content in the root area of apple tree root area of natural grass was significantly higher than that of pure tillage The p H value of the soil covered with grass is significantly lower than that of the pure and non rhizosphere soil;the exchangeable calcium,acid soluble calcium and organic combined calcium in the rhizosphere and non rhizosphere soil of the natural grass are significantly higher than those of the grass covered and the pure cultivated soil,and the exchangeable calcium,acid soluble calcium and organic combined calcium in the rhizosphere and non rhizosphere soil of the covered grass are lower than those of the natural grass.4.The content of exchangeable calcium,acid soluble calcium and organically bound calcium in root zone soil increased with the increase of citric acid content within 100 mg·Kg^-1.The content of calcium in root system,root activity,total length,total surface area,total volume,average diameter,number of root tips and root fractal dimension of Apple Rootstock（Malus hupehensis Rehd.）seedlings also increased.