The Seedling Growth Rhythm And The Response Of Nitrogen Fertilizations Of Mytilaria Laosensis Seedings

This study was to explore the growth rhythm of height and the ground diameter of Mytilaria laosensis seedlings, building the height growth curve of logistic model. Also, the study was to examine the effect of the seedling growth of Mytilaria laosensis under five nitrogen levels (N1:100mg/seedling, N2:200mg/seedling, N4:400mg/seedling, N6: 600mg/seedling, N8:800mg/seedling) and the control (CK:Omg/seedling). The indexes, containing the increment of ground diameter and seedling height, the total biomass, the chlorophyll content and the chlorophyll fluorescence parameters, were examined and analyzed to screen the optimum nitrogen application on promoting the growth of Mytilaria laosensis seedlings. The results show that:(1) The growth rhythms of seedling height and the ground diameter of Mytilaria laosensis seedlings were fit for the "S" curve. The height logistic model of Mytilaria laosensis seedlings was built According to the results of its equation, the whole growth period was divided into three periods:the growth prophase, the fast growing phase and the later growth phase. During the fast growing phase, the increment of seedling height was up to 8.56cm, which occupying 53.5% of the full-year growth. Therefore, to promote the growth of Mytilaria laosensis seedlings, the cultivating managements of the seedlings should be more careful.(2) Treated with five nitrogen levels, the index, including the increment of ground diameter and seedling height, the total biomass and the chlorophyll content, appeared a trend which was to up first then down, along with the increasing nitrogen application. While, the peak of the indexes (the increment of ground diameter and seedling height and the total biomass) appeared in N2, were 40.5cm,4.98mm and 4.07g, were 2.46 times,1.5times and 2.58 times of the control, successively, indicating that the nitrogen level of 200mg/seedling played a significant role in promoting the growth of Mytilaria laosensis seedlings. The peak of the chlorophyll content which was 1.54 times of the control, appeared in N4 (1.240 mg/g).(3) Compared to the Control, only were the FY/Fm、ΦPSn and qP of N2 Significantly higher than that of the control, followed by 0.79,0.69 and 0.92, which increased by 5.33%, 109.09% and 31.43% than the control, respectively; While the NPQ was significantly lower than the control, only was 0.22; these also indicated that, the nitrogen level of 200mg/seedling could significantly improve the efficiency of light use, promoting the growth of the Mytilaria laosensis seedlings, eventually.(4) Therefore, the optimum nitrogen application on promoting the growth of Mytilaria laosensis seedlings is 200mg/seedling.