Effects Of Arbuscular Mycorrhizal Fungi On Plant Growthand Calcium Uptake In Citrus Seedlings

Arbuscular mycorrhizal is a mutual beneficial symbionts which is formed by arbuscular mycorrhizal fungi and pla nt roots in the soil. Abuscular mycorrhizal fungi can help plant to absorb more water and nutrientsby enlarging plant roots, in turn, the plant provide carbohydrates to arbuscular mycorrhizal. What’s more, it also can improve the plant quality and enhance the plant resistance. Arbuscular mycorrhizal is getting the people more and more attention because of the important role in plant.Citrus fruit is widely cultivated in the south of C hina, which is important in increasing farmers’ income and stabilizing the economic development of the region. Citrus plants possess less or no root hairs in the fields and thus highly depends on arbuscular mycorrhizas to replace the root hair for nutrient uptake from soil.Calcium is the highest content of mineral elements in citrus, and it is of great significance in regulating the metabolism and development of citrus. Calcium is one of the majorelementfor plant growth. As a second messenger, calciuminvolves in various physiological processes in plant,and it plays an important role in maintaining the stability of the plant cell wall, cell membrane and membrane binding protein.Currently, nitrogen and phosphorus are the main research contents in the mineral nutrition metabolism of the mycorrhizal citrus seedlings. In contrast, there is little research on the calcium and the results are different. Therefore, tomake a basic theory of calcium nutrient absorption mechanism in citrus, this study took theTarocco Xinxi(Citrus sinensisOsbeck)inoculatedofGlomus mosseaeand Glomus etunicatumas test materials.The research includedplant growth effect, the content of inorganic nutrients, and different forms of calcium in the soil and plant root, as well as the different absorption capacity of different calcium, etc. The main findings were as follows:1.There was different infection rate of different arbuscular mycorrhizal fungi. The infection rate of G.m plant was higher 5.1% than the plant of G.e.Test showed that compared withGlomus etunicatum,Glomus mosseaewas more effective to the plant. Differentinfection rate had a different promotion on the plant growth. The influence of was more significant than Glomus etunicatum on plant height,stem diameter,root activity,chlorophyll,soluble sugar, soluble protein and other physiological indexes.2.Inoculation of arbuscular mycorrhizal fungi promoted citrus growth and the absorption of N, P, K. C itrus seedlings after inoculation of arbuscular mycorrhizal fungi were significantly higher thanuninoculated controls in plant root activity,chlorophyll, soluble sugar, soluble protein and other physiological indexes. It also increased the absorptionof N,P and K when citrus seedlings was inoculated with AMF. It made citrus seedlings in a higher nutrition level. The content of nitrogen and phosphorus in leaves were higher than those in roots. O n the contrary, the content of potassium in roots was higher than those in leaves.3.The forms and content of calcium in soil and root of the citrus were changed when the citrus plant was inoculated of arbuscular mycorrhizal fungi, and inoculation made the transformation of the calcium forms be beneficial to the plant uptake.The content of 5 different forms of calcium of the inoculated plant and uninoculated plant in the soil were in the same changing trend from July to September.The changing trend was increase first,then decrease.The content of exchangeable calcium,organic calcium and acid soluble calcium in soil of the inoculated citrus were higher than those in soil of the uninoculated one in November. On the contrary, the content of water-soluble calcium and residue calcium were lower than those in soil of the uninoculated one. The amount of calcium with high efficiency for plant in soil of the inoculated citrus, including water-soluble calcium and exchangeable calcium were higher than the soil of uninoculated one. In November, the citrus seedlings inoculated of arbuscular mycorrhizal fungi increased the content of inorganic calcium, water-soluble calcium and pectin calcium in plant root, and decreased the content of oxalate calcium and phosphate calcium.4.The plant was in a higher nutrition level of N,P and K because of inoculation of arbuscular mycorrhizal fungi. The plant were inoculated different arbuscular mycorrhizalfungi, namely CK, G.m and G.e. The regulation of deionized water and 5nmol/L calcium nitrate, calcium acetate, EGTA on the content of calcium and CaM in root on those three groups were investigated to compare the absorption capacity of four different calcium supplements. The results showed that calcium nitrate were more suitable to increase the content of calcium and CaM in root.