| |The experiment using 2-year-old potted Fuji (Malus domestica cv.Fuji) and flourishing period apple trees in the field as main materials was carried out in Shandong Agricultural university and Chaoquan apple orchard of Feicheng from 2007 to 2010. It mainly studied the effects of different zinc levels on growth development of apple trees and the rhythm of zinc and other micronutrients absorption and distribution in different organs, exploring the key factors and sensitive developmental period of zinc deficieny,clarifying the changes of apple trees transfer coefficient under zinc deficiency.It lay the foundation for the scientific regulation of zinc nutritional status of apple trees and promoting the enrichment of zinc to the fruits and other economic organs, finally, establish dynamic management models for zinc nutrition.The mainresults are as follows:1. the growth of apple trees and dry matter accumulation were both significantly inhibited under low and high zinc treatment, the amount of dry matter accumulation was only 86.05% and 78.84% of that normal zinc treatment The growth of root was inhibited under high zinc treatment and biomass was only 73.08% of normal tree at later growth stage, while above ground behaved zinc poisoning symptoms such as etiolation and droped of leaves,and the dry matter accumulation was becoming negative. Under the low zinc stress, the disease of rosette leaves mainly happened on spring branch for incidence of the tree for the previous year, but for the previous year, the disease of zinc deficiency mainly on the fall branch2. The fresh weight, dry weight of fruits and the yield per plant under low zn stress showed a significant decraseing trend compared with normal trees, and only reached to 71.83%, 81.51% and 33.71% of that in the normal orchard, and the fruit production was also decreased. In addition, each index of the quality of fruits in diseased trees were well below the standard of excellent fruit, and have great effcets on the internal quality, such as taste and flavor of fruit. Soluble solids, soluble sugar, sugar acid ratio of fruits of diseased trees is only 83.43%, 51.51% and 33.72% of that in normal orchard, but the titratable acid content was significantly higher than the normal trees,was about 1.44 times of the that in normal ones.3.Zinc contents and accumulation rate in different organs of apple trees showed a rapid upward trend with the increasing levels of zinc supplyment. The zinc content of other organs of apple trees showed a rise-and-fall motif except roots under low zinc treatment. Zinc contents of the roots, stems and leaves in young apple trees showed a slowly increasing trend under normal zinc treatment., while it always maintain a level of stable content at 40-50mg/kg in shoots, and the concentration of leaves was significantly higher than other organs.The zinc concentration in different organs of young apple trees under high zinc tratment exceeded the standard value significiantly at late develop period.and behaved significantly symptoms of zinc poisoning, and the accumulation of zinc above ground was higher than that in root.4. The annual dynamic changes of zinc absorption, translocation and distribution of apple trees were changed in zinc deficiency orchard, the potential absorption in roots of normal trees was relatively higher, and zinc contents of perennial branches was stable and kept high levels of zinc nutrition consistenting with the organogenesis rhythms. while zinc contents of disease tree was declining in the early stage,and showed rapid rise in the late stage. The large fluctuation indued the disease trees formated the special law that in spring and summer the capacity of providing zinc of roots was lower .but large ammunt of zinc storaged in the root and difficult to transport to the above ground at later growth stage ,and has lower zinc supplement on the stage og the differentiation of organs . Perennial branches of diseased trees was significantly decreased.The variation of zinc contents in new organs had the same trend. But level of zinc content in the fruit and the new branch of the normal tree was higher than diseased trees.5. The distribution ratios of zinc in roots and stems were significantly decreased due to the rapid growth of new organs at the stage of stop growing of spring branch, but the proportion in new organ had a rapid increase,and the ratio was of 30% -49%. The ratio of distribution of roots in low zinc stress was significantly lower than that of other treatment, only 72.56% and 73.46% of that respectively, but it was in the opposite the stem at Later development stage, zinc distribution ratio of young tree leaf decreased rapidly at different zinc levels at later development period and the nutrient of leaves began to return, zinc distribution ratio of branches and stems under high zinc stress significantly increased,but more zinc storged in roots under low zinc stress this this time, the ratio of zinc were 1.28 and 1.30 times of that of normal zinc and high zinc treatment.6 The effect of zinc on the absorption and accumulation of iron, copper, manganese had different performanceat different developmental stages. It was controlled by many factors. Different organs, zinc levels and different developmental stages had different performance for other elements. |
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