| Pear is one of the most popular worldwide fruit in favor with consumers. Recent years, although the amount of production and exports of pears continued to rise in China, there were still many problems existing in the production and management of pear, such as extensive management, the disorder of irrigation and fertilization and lack of pest control, etc. To investigate the amount of mineral nutrients lost from mature pear trees, we determined the nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) content in the pruned branches of various ages, fallen leaves, and mature fruit of four varieties (Huangguan, Lvbaoshi, Yuanhuang, and Yali) of 15-year-old pear trees growing in the same orchard. And the weight of pruned branches, fallen leaves and the total fruit weight per tree were also calculated. Furthermore, a study was carried out to investigate the soil properties, the growth of the tree and the rot disease incidence through a field experiment of different organic fertilizer treatments on the Bartlett for the last five years. Results are as follows:1. The nutrient abundance ranged from Ca>N>K>Mg>P in the pruned branches and fallen leaves of all four varieties, whereas it ranged from K>N>P>Ca>Mg in the fruit. The N, K, and P contents decreased with increasing age of the pruned branches. The Ca and Mg contents in the fallen leaves were about 58%and 100%higher than in the pruned branches, but 44-fold and 6-fold that of the fruit. The annual loss of N, P, K, Ca, and Mg from pear trees by pruning, leaf abscission, and fruit harvest was about 184.5,19.5,99.1,307.5, and 26.7 kg/hm2, respectively, of which 31～58% was due to pruning. The percentage of N, Ca, and Mg lost through fallen leaves was higher than that lost through fruit, being around 7.1%～33.3% in N of fruit,1.8%～2.2%, and 8.0%～16.3% in Ca of fruit and Mg of fruit, respectively. However, the loss of P and K through fallen leaves was less than through fruit, which was around 31%～60% and 36%～61%, respectively. Among the varieties tested, Huangguan trees exhibited the greatest loss in nutrients through pruning and fruit harvest, with the exception of Yali, which lost more N and K through falling leaves than did Huangguang.2. Compared to the control, the Bartlett yields applied by four kinds of organic fertilizers were increased by 18%-30%. The chlorophyll content, leaf area, leaves weight and the length of shoots of trees applied by four-kinds of organic fertilizers exerted different degrees of increase in contrast to control, among them the effect of BOF1 was optimal. The fruit of the trees applied by the BOF1 exerted an especially significant reduction in the soluble acidity. Furthermore, organic fertilizers have certain effect to enhance the disease resistance of pear tree, especially the treatment of BOF1 showed a low rot disease incidence. The quantity of bacteria, fungi, actinomycetes of the soils applied by the organic fertilizers are higher than that of control and the effect of BOF1 was particularly remarkable during the whole growth period of pear. The elements content of the pear leaves from young fruit stage to maturity stage and the fruit all decreased with the increase of growing. The content of N, P and K of the leaves in the three growth period were N>K>P; and the content of N, P and K of the fruit from expanding period to mature period was K>N>P. The improvement and strengthen of the mineral nutrient content and the accumulation content of pear trees were found during each growth period. The effect of BOF1 treatment was obvious by significantly increasing the amount of K accumulation of both leaves and fruits. |
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