The Effect Of Inoculating Of AM Fungi On The Zn Absorption

The genus citrus is a member of Citrus Linn of Rutaceae. The fruit of citrus is delicious, rich in nutrient and can be eaten raw, which also can be processed into kinds of production including juice. Citrus has high and stable, so it can create high economic value, which has become the most important fruit trees in the southern of China. It plays a significant role in developing rural economy.In China, although there are many reports of Zn contaminated soil, but Zn deficiency was still up to the 40% of the soil nationwide. In citrus production, the Zn deficiency is because of the different of soil content and the plant demand. Impropriety application of N,P,K and Ca fertilization in Citrus prodution in Chongqing, also bring about Zn deficiency, restricting crop production. In recent reports, Zn deficiency become one of limiting factor of citrus quality and high yield.On the other hand, Citrus is mycorrhizal symbiosis plant. Citrus growth depend on the mycorrhizal.The arbuscular mycorrhiza is a sort of beneficial symbiont which engenders between plant roots and soil fungi during the course of the plant's growth. It is known that the AMF can promote plant growth and improve the plant's ability resisting against environmental stress. Due to the positive effects of AMF, the studies and utilization of AM biotechnology have being paid enormous attention. So, if proper AMF inoculated in roots of cirus plantlets, the growth of the plantlets and the ability against the environmental stress will be greatly improved. So choose the suitable AMF is important for increasing the transplant survival rate, growth potential and the nursery stock quality.In this paper, the first experiment was carried out to research the correlation between the happening of Zn-deficient chlorosis and the Zn contents of cirus leaves; The second experiment was carried out with the Carrizo citrange (Citrus sinensis Osbeck x Poncirus trifoliata (L.) Raf.)as materials.In this test there were three treatments by three diffrent arbuscular mycorrhizal fungi of Glomus in order to evaluate the effect and mechanism of AM fungi on Zn uptake in citrus in different soil pH. By measuring citrus growth and physiological and biological indexes such as SOD,POD,leaf chlorophyll,leaf Photosynthetic utilization,root activity and fruit in citrust, the application efficiency of mycorrhiza was valued; The third experiment was carried out in field to study the effect of Zn-fertilizers application on the Zn deficient chlorosis correction and the improvement of fruit quality of citrus.The main results of this study are as follows:1. Zn deficience caused the leaf chlorosis of citrus plants. Zn contents of normal leaves are higher significantly than chlorosis leaves. In this study, Zn content of leaves in June is higher during the testing period and the suitable indicators is above 35μg.g-1. So this paper shouws that the appropriate standards of Zn contents of citus plants related to sampling time and cultivars.2. Zn deficiency stress decreased the chlorophyll content of citrus leaves. Chlorophyll contents of chlorosis leaves 1.033 mg·g-1Fw is lower than normal leaves 1.68·9 mg·g-1FW. However contents of carotenoids there are not significant difference.3. Zn deficiency restriction shoot growth of citrus. The spring shoots and leaf area of chlorosis leaves were lower than healthy leaves.4. The AMF can promote citrus to absorb Zn in soil, Zn contents of citrus leaves of mycorrhizal inoculation are higher than that with no in oculation in suitable soil pH; Mycorrhizal inoculation and Zn promoted roots growth of citrus, increase root activity of citrus, which illustrate that mycorrhizal inoculation can improve the physiological activities of citrus plants in high pH calcareous soil.5. Mycorrhizal inoculation and high Zn appliction (1.0gZn+AM) increased photosynthetic efficience significantly compared with the low Zn treatment (0.5gZn-AM). The results showed that mycorrhizal inoculation and Zn treatment promoted photosynthesis of citrus effectively.6. The results showed that Zn deficiency affected the activities of leaf protective and enzymes growth of Carrizo citrange, and the content of chlorophyll significantly, the activities of leaf SOD, POD also increased significantly.7. Zn treatment increased the fruit weight, and juice yield significantly. Thus Zn application improve the quality of fruit and economic output.