Effects Of Arbuscular Mycorrhizal Fungi On The Growth And Salt Tolerance Of Pyrus Betulaefolia Seedlings

The phenomenon of soil salinization and secondary salinization in the global scope are widespread, it have a serious impact on the sustainable development of the agriculture and animal husbandry, ecological environment, and is one of the important environmental problem at present. In existing measures of saline-alkali improvement, biological improvement measures is considered the most effective ways to improve the economy, by screening excellent salt-resistance varieties that can be suited for salt environment to develop and utilize saline-alkali land, and in combination with microbes symbiotic relationship with plants to improve plant salt resistance is one of the new research direction.Arbuscular mycorrhizal fungi can form mutualistic symbiosis relationship with plants, they have promote the growth of host plants, and improve plant nutrition absorption, increase the role of plant resistance. And at home and abroad have done a lot about using mycorrhizal fungi to improve plant salt resistance, but mainly in the trees, trees and crops, etc, while for the study of application of mycorrhizal fungi to improve the salt tolerance of fruit trees is still few. Pyrus betulaefolia as a cold, water logging, moderate salt tolerance characteristics of fruit tree species, its ability to adapt to the soil environment is very strong, and is applied widely in the north and south as grafting rootstocks of pear trees, but the seedlings in planting and development of saline-alkali land there are still exist the low culticated survival rate and poor plant growth.In this paper, it mainly setting three different kinds of arbuscular mycorrhizal fungi as inoculants, and vaccination in annual Pyrus betulaefolia seedlings, and study the effects of arbuscular mycorrhizal fungi on plants under different concentrations of NaCl treatment,and discusses the effects and physiological mechanism of AMF in improve plant salt resistance, respectively from growth conditions, absorption of mineral elements, osmotic adjustment, membrane system and antioxidant enzyme protection system aspects, the main research results were as follows:1) NaCl stress can inhibit the growth of Pyrus betulaefolia seedling leaves, salt injury index of plant increased with the increase of NaCl concentration. For Pyrus betulaefolia seedlings inoculated with AM fungi, can significantly reduce injuries to the leaves, reduce salt harm degree and the salt damage limit value. Inoculated with AM fungi also alleviate salt stress injury to the plant leaf number, leaf area, increase the total chlorophyll content of plant leaves and carotenoid content, but the effects on plant height are not obvious. Three kinds of AM fungi’s ability to infect Pyrus betulaefolia seedlings from big to small is:Glomus intraradices> Glomus mosseae> Glomus versiforme.2) The plants inoculated with AM fungi can promote the absorption of the plants on the N, P^K elements, reduce the content of Na+in plants, reduce proline content of leaves, increase soluble protein, soluble sugar content of plant leaves, alleviate the influence of NaCl stress on plant osmotic balance, improve plants osmotic regulation ability, increase their salt resistance.3) AM fungi can reduce the damage of leaf membrane system by stress, reduce the relative conductivity of the blade, and improved the SOD, POD and CAT activity in Pyrus betulaefolia seedlings cells, enhances the antioxidant protective enzyme system in plant, thereby inhibiting the plasmalemma peroxidation in plants caused by stress. AM fungi was significantly decreased the malondialdehyde content in the leaves of plants.4) Based on the test results, we concluded that the effect of different AM fungi on Pyrus betulaefolia seedlings under different degree NaCl stress were different. A comprehensive comparison of three kinds of AM fungi can be found, the improving ability of Glomus mosseae and Glomus intraradices on Pyrus betulaefolia seedlings salt resistance is stronger, the enhancement effect of Glomus versiforme on salt resistance is slightly less, this showing a positive correlation with the infection rate of the three fungi on plants.5) We also found that when the Pyrus betulaefolia seedlings were higher than the concentration of0.4g/kg NaCl treatment, can severely inhibit plant normal growth, in about one month after all the plants were withered and died, but at the beginning of the high salt stress, vaccination AM can significantly alleviate the stress harm that plants suffered. when in the middle and lower salt concentration, AM fungi can effectively reduce the stress injury that plants suffered, and improve the salt tolerance of plants.