Study On Physiological Mechanism And Application Of Apple Trees Under Partial Rootzone Irrigation

There are two serious problems in Chinese agriculture. The water resource is not enough for agriculture but most of water were wasted because of flood irrigation. Partial rootzone irrigation (PRI) is a novel irrigation technique which improves the water use efficiency when the production isn't decreased. The technique requires that only partial root system is always maintained in a dry or drying state while the remainder of the root system is irrigated. The wetted and dried sides of the root system are alternated after a period of time. In experiment we used two or three years old splits–root potted apple trees (Royal Gala), where the root system was divided between four containers. There are five experiment groups of irrigations : complete irrigated part, 3/4, 2/4, 1/4 and no irrigation part. In the condition of no rainfall we had studied only 1/4, 2/4, 3/4 rootzone alternative or fixed irrigating apple trees'condition of water, growth of roots and shoots, the changes of plant's physiological functions, endogenous hormones, drought resistance and water use efficiency and so on. We also had studied on the grown Fuji apple trees of applying partial rootzone irrigation. The main results are as follows:1. Only 1/4, 2/4, 3/4 rootzone irrigation can save water quantity 75%, 50%, 25% than whole rootzone irrigation. But the plants of only 2/4, 3/4 rootzone alternant irrigation could satisfy the needing of water in the whole growth moment, whose leaves water potential and leaf water relative content are the same with the whole rootzone irrigating plants. Only 1/4 rootzone irrigation can not apply enough water for apple plants in summer or autumn, whose small leaves was etiolated. The plants of only 1/4, 2/4, 3/4 rootzone fixed irrigation from the rudimentary could sustain the well-balanced water condition.2. The shoot growth rate of the plants of only 1/4, 2/4 rootzone irrigation decreased about 37.3%, 28.6% the whole rootzone irrigated plants.flowering trees and number of buds and the rates of fruits setting were increased than the plants of whole rootzone irrigation. But only 3/4 rootzone irrigated plants had not significant difference with the plants of whole rootzone irrigation.3. The distribution of root's density of plants only 2/4, 3/4 rootzone alternant irrigation were more well-proportioned in the soil than the whole rootzone irrigated plants. The plants...