Evaluation Of Application Effects Of Organic Fertilizers And Diagnostic Indicators Of Iron-deficiency Chlorosis In Sand Pear Trees

The sand pear cultivar’Akiba’ (Pyrus pyrifolia Nakai cv. Akiba) and ’Niitaka’(Pyrus pyrifolia Nakai cv. Niitaka)were used as experimental materials. The effects of different organic fertilizers on the physical and chemical indicators in soils, the content changes of main nutrient elements in fibrous roots, flowers, leaves and fruits as well as yield and quality of Akiba were compared, the content changes of total iron, active iron and ferrous iron in the different organs of normal and chlorosis Niitaka were analyzed as well as the appropriate diagnostic indicators of iron-deficiency chlorosis were explored. The main results were as follows:1. The effects of organic fertilizers on the related physical and chemical indexes in soils:the content of organic matter was the lowest and the water soluble salt content was the highest in soils treated by chicken manure among the four organic fertilizers treatments. The water soluble salt content treated by rape seed cake was lower than other treatments. The content of organic matter treated by vermicompost was higher than that by the others, and the content of available iron(Fe) in soils treated by vermicompost was higher than rape seed cake treatment remarkably. The available zinc(Zn) content in soils was increased treated by sheep fillers significantly.2. The effects of organic fertilizers on content changes of main mineral elements in fibrous roots of Akiba:the content of total nitrogen(N) in fibrous roots treated by chicken manure was the best among the four organic fertilizers treatments, the rape seed cake could promote the absorption phosphorus(P), manganese(Mn), Fe for fibrous roots as well as the content of Zn in fibrous roots treated by vermicompost was higher than other treatments, which was 1.40 times than that treated by sheep fillers.3. The effects of organic fertilizers on the mineral nutrition of flowers, leaves as well as yield and quality of fruits:the content of Fe in flowers and the per fruit weight, the yield per plant, the fruit firmness as well as the contents of soluble solid and soluble sugar treated by chicken manure were increased remarkably. The vermicompost could promote Mn content in flowers and the contents of Fe, Mn, Zn in leaves remarkably. The Zn content in flowers and the contents of Fe, Mn in fruits were increased significantly as well as flavour of fruits was improved treated by rape seed cake effectively.4. In order to solve the problems of ferrous iron contents in in plant tissues, the contents of ferrous iron were studied by NH4F masking method in this paper. The results showed that the determination coefficient and coefficient of variation were 0.9998 and 10.23% respectively and the recovery was up to 100.82% when 0.15% phenanthroline 2 mL and 3 mol/LNH4F 2 mL were added in turn without sulfuric acid or hydrochloric acid to adjust pH.5. The exploration of diagnostic indicators of iron nutrition status of Niitaka:the total iron contents in flowers, leaves, branches and roots were not appropriate for evaluating iron nutritional status, but the content changes of Fe2+ and active iron in flowers and leaves could be used as diagnostic indicators of iron nutrition status. What’s more, the content changes of Fe2+ in flowers could reflect iron nutrition status more timelv and accurately.