Carbohydrate Metabolism In Fruit Trees Under Water Stress Applied During The Early Stage Of Fruit Development

Water-saving cultivation during period which fruit tree is non-sensitive to water stress (regulated deficit irrigation)have wide using potential in China in the future,and it has very important significance to the continuous-development of agriculture. Studies were concertration on the carbon nutrition of source and sink organs of fruit tree,by using potted mature'Jonagold'apple(Malus domestica Borkh.'Jonagold')and mature'NJN 76'peach(Prunus persica(L.)Batsch.cv.NJN76)tree as experiment metarials,and water stress treatments were imposed to them at early period of fruit development. In order to study the mechanism of carbohydrate metabolism of fruit tree under condition of water-saving cultivation during period non-sensitive to water stress,the responses of development and growth,dry weight,and the transport and distribution of assimilate,and the concertration of carbohydrate and the activities of related enzymes of source and sink organ to water stress and stress relief were studied.Results indicated that the growth of fruit,shoot and trunk of apple and peach all delayed under water stress condition. When stress relieved,the growth of fruit of the two fruit tree all renewed and even exceeded the control,growth of shoot and trunk of apple and peach tree all were not renewed. The ratio of roots/shoots and roots/leaves of apple and peach all increased under water stress condition,and when stress recovered,the ratio of roots/shoots and roots/leaves of apple all recovered to control,but that of peach still kept a higher level than control. The concentration of soluble sugar and starch in source leaves affected by water stress.When the trees applied to water stress if compared with the well- irrigated trees,the concentration of total sugar,reducing sugar,sorbitol,glucose and fructose increased significantly in apple and peach leaves,a low concentration of starch was observed in peach leaves,and in the first two drought cycles in apple leaves,but the response of concentration of sucrose in apple leaves was not consistent with that of peach leaves,in apple leaves,sucrose concentration was not affected by water stress,but in peach leaves,it decreased. Except for an after-effects were obvious on the concentration of a few carbohydrate,such as in apple leaves,significant high concentration of glucose and fructose could be observed two days after removing water stress on the trees submitted to water stress as compared with the control trees,and in peach leaves,the concentration of sucrose and starch increased,most of the other carbohydrate all renewed to control level when stress relieved.Water stress influenced activities of the relative enzymes to the carbohydrates metabolism. The activities of aldose-6-phosphate reductase(A6PR)and sucrose phosphate synthase(SPS),...