Research Of Seedling Characters And Eco-physiological Indicators Of Introduced Pecan Varieties

In this study twenty-five Pecan varieties were introduced from America by the comparative experiment through sowing seeds, cultivating nursery stock and planting conditions in the different area. The result showed that the fast-growing varieties include Forkert and Elliott for the 1 year-old seedling seedling with height (H) 48.1cm and base diameter (BD) 0.88cm. The varieties with the highest survival percentage after transplant were Harris (97.5%) and Fayette (93.8%). Based on the growth, James, Wan Keenah and Harris super grew better in Huaibei plain, their mean height and base diameter were 228cm and 3.21cm, 221cm and 3.19cm, 217cm and 3.48cm respectively; James, Sdling csv13-14 and San Fehpe in the western area of the hillock between Changjiang river and Huaihe river, H and BD were 310cm and 3.19cm, 240cm and 2.97cm, 244cm and 2.82cm respectively; Moore and Sdling 10-5 in the east of Anhui, H and BD were 265cm and 3.43cm, 215cm and 3.35cm respectively; San Fehpe in Dabie Mountains, H and BD were 201cm and 3.33cm. They were treated with 0.1% ZnSO4·7H2O +0.2% CO(NH2)2 after seedling came out the soil. The result showed that varieties with the highest increase percentage of BD were Moore and riverside, they were 72.3% and 69.9% respectively. Pecan is one of the tree species of spring growth. The height increase in fast growth period covered 87.5% of whole-year. Dynamics of the base diameter growth showed two peaks of which one appeared in the end of May and another in the beginning of August. The height growth had only one peak in the end of May. After transplant, however, the base diameter growth appeared one peak with longer period (from June to August). There was no significant difference in the height growth between years while significant difference appeared for BD growth between years. This result may be resulted from rootcutting which enhance root developmental growth. The light compensation point for photosynthesis ranged from 20 to 50μmol·m-2s^-1 for all varieties. The light saturation point for photosynthesis ranged from 1000 to 1500μmol·m-2s^-1. Diurnal changes of the net photosynthesis rate had two peaks that appeared at 10 o'clock and 14 o'clock. In Apr., Jun. and Sep., the average net photosynthesis rates were 5.27, 21.29, 1.81μmolCO2m-2s^-1 respectively, the average transpiration rates are 2.00, 3.35, 2.49 mmolH2O-2s^-1 respectively.