Effect Of Water And Fertilizer Coupling Modes On Soil Nutrients As Well As Growth And Development In Pears

With six years old Huangguan pear trees, the effect of different water-fertilizer coupling modes on soil and leaf nutrient contents was studied in order to screen out a better combination by referring to some growth and development indexes. The main results are as follows:1. Dynamic change of soil N contents: The soil alkali-hydrolysable N contents with most treatments were significantly higher than the control in mid April, with NT and NH treatments being the highest at 0~20 cm and 20~50 cm soil layers. In late May, the hydrolysable N contents were the highest with NT and NH treatments at 0~20 cm soil layer, significantly higher than other treatments. In late July at 0~20 cm and 20~50 cm soil layers, the hydrolysable N content was higher with NH treatment and it was the highest at 50~80 cm soil layer.x In early September, the hydrolysable N contents with NT and NH treatments were the highest at three soil layers. Averagely, NH treatment could maintain higher soil available nitrogen contents during growing season.2 Dynamic chang of soil P contents: As for the available P contents, NT and NH treatments were higher in late May. In late July, the available P content with NH treatment was the highest at 0~20 cm soil layer. As for available P contents, at 0~20 cm soil layer, NT and NH treatments were the highest in early September, and at 20~50 cm and 50~80 cm soil layers, NT treatment was the highest with NH treatment being next to it, significantly higher than most of the treatments.3. Dynamic change of soil K contents: At 20~50 cm soil layer the available K content of NT treatment was the highest in late May. The available K contents were the highest with NT treatment at three soil layers in early September.4. Dynamic change of leaf nutrient contents: Under different water-fertilizer coupling conditions, leaf N, K and Fe contents were the highest with NH treatment and the leaf B level with NT treatment was also significantly higher than the control. Leaf Mn content was the highest with NT treatment and it was also higher with NH than with other treatments.5. In view of growth and development of pear trees, NH treatment had smallest trunk girth growth except the control and higher proportion of spurs, and the average fruit weight was higher with the highest SSC, soluble sugar contents and ratio of sugar to acid.6. Among different treatments, the Normal water + Half fertilizer(NH) was the best, with the highest leaf Pn, SSC and titratable acidity being 13.4μmol·m-2 ·s-1, 13.70% and 0.111%, respectively, significantly higher than the control and most treatments. However, there was no significant difference in fruit firmness among all the treatments. Therefore, for sake of economical fertilization and favorable effect on improving fruit quality, the NH mode is recommended when pear tress are being dressed.