| Nanguo’pear is a superior varietiy with large cultivation area and strong representative in Liaoning province. This research was carried in the pear orchard to investigate the nutrient absorption and accumulation of ’Nanguo’ pear trees from1to17year-old and the characteristic of nutrient accumulation in different growth stages (bud break, bloom, fruit setting, fruit expansion, fruit coloring, fruit ripening, after fruit harvest and before leaf falling) of12year ’Nanguo’ pear tree to determine the optimum fertilization rate. Based on the optimum fertilization rate, different manure-N to chemical fertilizer-N ratios were used to reduce the chemical fertilizer input, in order to ensure the higher production and quality of ’Nanguo’ pear with the lower nutrients accumulation and environmental load, which can guarantee the sustainable development of ’Nanguo’ pear industry. Major results were summarized as follows:1. There were significant positive correlation between accumulations of dry matter and nutrients (N, P, K), and tree ages of ’Nanguo’ pear. And related models can be used to forecast yield, nutrient uptake in annual organs of new shoots, leaves and fruits and storage perennial organs of root, stem and branches to make sure NPK of the total uptake amount in ’Nanguo’ pear trees.2. Annual net accumulation of dry matter of12-year ’Nanguo’ pear was16.4kg, in which the accumulation in new growth and perennial organs accounted for58.9%and41.1%, respectively. Annual net uptake of N, P and K were146.2,17.1and146.1g/tree of ’Nanguo’pear trees. And the uptake amount of N, P and K were5.73,0.81and5.80kg to produce1000kg market fruits.3. Under same N input condition, compared to application of chemical fertilizer or manure, combination of chemical fertilizer and manure (F6M4and F4M6) significantly increased fruit setting rate and weight, which in turn increased yield. Combination of chemical fertilizer and manure (F6M4and F4M6) or manure (F0M10) application significantly increased contents of total sugar, soluble solid and anthocyanin, and hardness of fruits. The fruits in F6M4treatments have better flavor due to the increase of contents of glucose, fructose, malic acid and citric acid.4. Only application of manure significantly decreased soil bulk density, increased total soil porosity and water retention capacity in0-40cm depth soil. Soil organic matter, total N and pH tended to increase with the increase of application rate of manure. Combined application of manure and chemical fertilizer significantly increased contents of nitrate N, available P and K and maintained high nutrient levels in soil after fruit setting. Combined application of manure and chemical fertilizer significantly also increased activity of urease, phosphatase and catalase in soil.5. From2011to2013, the total N input rate was700kg/hm2in each treatment; the total P input rate were152kg/hm2(F10M0, F6M4),202kg/hm2(F4M6) and273kg/hm2(F0M10), respectively; the total K input rate were578kg/hm2(F10M0, F6M4and F4M6) and611kg/hm2(F0M10) in trial ’Nanguo’ pear orchard. The F6M4treatment had the highest net removals of N, P and K, with the values of324,42and299kg/hm2, respectively, and the lowest supluses of N, P and K, with the values of376, 110and279kg/hm2, repectively. The F0M10treatment had the lowest net removals of N, P and K, with the values of287,37and279kg/hm2, respectively and the highest suplused of N, P and K, with the values of413,236and332kg/hm2, repectively, especially the P suplus that result in high environmental risk.Comprehensive consideration of yield and quality of Nanguo’ pear fruits and nutrient surplus in orchard, the treatments of combined with manure and chemical fertilizer have better effect as compared to single manure or chemical fertilizer application. The manure-N to chemical fertilizer-N ratio is recommended for Nanguo’ pear fertilization. |
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