Study On Effects Of Arbuscular Mycorrhizal Fungi On Severe Drought And Heat Wave Resistance Of Kiwifruit Cuttings

Kiwifruit is a kind of plant which belongs to genus Actinidia in family Actinidiaceae.China is the center of kiwifruit origin and distribution,with a rich germplasm resource.Kiwifruit is famous for rich Vitamin C content,praised as the king of fruits.It is not intolerant to drought and heat which can easily make damage on the plant.Arbuscular mycorrhizal fungi(AMF)can improve plant water status and increase resistance of fruit tree roots to high temperature.Based on the orchard investigation and resistance index evaluation for 3 years old kiwifruit plants during hot and dry weather period,3 kinds of AMF including Glomus mosseae,Glomus diaphanum and Glomus versiforme were inoculated onto potted kiwifruit cuttings to systematically study the effects of AMF on the growth,NPK alimentation,photosynthesis,leaf water status and other resistance index of kiwifruit cuttings under the heat stress with different levels of 30℃,40℃and 45℃,the drought stress with different levels of normal irrigation,middle and severe drought and the combined stress of heat and drought,as well as to establish a biophylaxis system to reduce the affect of heat & drought stress on plant growth and resistance index by the way of AMF inoculation.The results are as follows.1 The AMF inoculation had a great effect on kiwifruit cuttings,with better results in plant dry weight,ratio of root to canopy and single leaf area in comparison with control.2 Under 3 stress treatments,the AMF inoculation significantly increased plant root vigor,enhanced the root absorbency to mineral nutrients,increased N,P,K contents in leaves,improved the leaf water status,promoted the plant photosynthesis,strengthened the vigor of leaf membrane protective enzyme and the content of osmoregulation substances,effectively relieved the water stress damage to plants,reduced the overoxidation of membrane lipid and its damage to leaf proteins,and moreover, promoted plant growth and tolerance to drought stress.3 As the degree of stress became higher,the AMF inoculation showed stronger effects than under normal condition,indicating that AMF is more effective under adverse condition.Meanwhile,it was found that there existed a certain reciprocal selection between AMF and host plants,as well as a certain requirement to environmental condition. 4 Glomus mosseae had a higher infection rate on kiwifruit cuttings and a better effect on plant growth,especially on K absorbency and accumulation,in comparison with Glomus diaphanum and Glomus versiforme,Therefore,Glomus mosseae is one of the best AMF strains for kiwifruit plants.