Research On Regulation Of Root-Zone Water Statue And Apple Growth Rhythm

Apple, as one of the primary plant fruits in China, mainly distributed in the arid and semi-arid mountains and hilly areas in which the soil is always in long-run water logging due to the natural precipitation there differs with time and space, alternative drought and flood, and the wild use of flooding method. These factors have great impact on the growth of apple tree, output and quality of fruits. Dwarf culture is the trend of apple cultivation now, so finding the water content which is appropriate for dwarf and close spacing culture is an important way to realize the apple water-saving cultivation.The experiment was carried out with three-year-old pot-cultured Fuji young apple trees grafted on different dwaft rootstocks, studies the influence of different soil water content on plant’s growth, main photosynthesis parameters, water metabolism index, long-term water use efficiency, cell membrane system and the influence of osmotic regulation, to investigate the appropriate soil moisture content for quality apple, providing references for precise irrigation of apple and improving water use efficiency. The results are summarized as below:1 With the decreasing of soil content, new shoots growth of all tested materials significantly decreased, Fuji / JM7 was the smallest among the tested materials decreasing range. New shoots of all apple trees acquired the second growth as soil relative water content reached (75±5)%, (60±5)%, and higher soil water content resulted in earlier growth time for the second growth of new shoots. New shoots growth and time of new shoots second growth was regulated by soil water content.2 With the decreasing of soil water content, chlorophyll content of all tested materials was not decreased. Chlorophyll content of Fuji / SH40 was significantly higher than two other materials in the suspending stage of spring and growth stage of autumn. It is not good for the chlorophyll synthesis, when the soil is in the high water content condition for a long time. While the chlorophyll content can increase by appropriatly reducing soil water content.3 With the decreasing of soil water content, the Leaf RWC, Pn, Tr, Gs of all tested materials reduced, Pn in growth stage of autumn decreased most. While instantaneous WUE of all tested materials was slightly increased slightly, but the long-term WUE was significantly decreased as soil relative water content reached (45±5)%. Compared with the CK, Tr of Fuji / JM7 dropped most, instantaneous WUE increased most, and long-term WUE of Fuji / JM7 was the highest as soil relative water content reached(75±5)% and(60±5)%. With the decreasing of soil water content, Pn of Fuji / SH28 decreased most. With different treatments, daiyl variation of Pn, Tr, Gs daiyl variation showed a pattern of single peak.4 With the decreasing of soil water content, MDA and Pro content of all tested materials rose rapidly. MDA content of Fuji / JM7 rose less, Pro content increased more. It shows that to some extent, Fuji / JM7 accommodates the drop in soil water content.5 In this study, (60±5)% was the appropriate soil relative water content according to maintaining plant growth and increasing water use efficiency.