不同氮素水平对米老排苗期生长和叶绿素荧光特性的影响

Effects of Nitrogen Fertilization on Growth Performance and Chlorophyll Fluorescence Parameters of Mytilaria laosensis Seedlings

为探讨不同氮素水平对米老排苗期生长的影响,采用根部施肥的方法,研究了5个氮素条件下(总施氮量分别是100、200、400、600mg·株^(-1)和800mg·株^(-1))米老排幼苗生长和荧光特性的差异。结果表明:1)米老排的苗高、地径和总生物量均会随着施用氮素水平的增加,呈现先升高后降低的规律,均在N2(200mg·株^(-1))时达到最大值(40.52cm、4.98mm和4.07g),依次较对照处理提高了145.7%、152.8%和158.4%;2)氮肥能够促进米老排幼苗叶片叶绿素含量的增加;3)随着氮水平的增加,实际光化学效率(Φ_(PSⅡ))、PSⅡ最大光化学效率(F_v/F_m)、光化学猝灭系数(qP)均是先升高后降低,非光化学猝灭系数(NPQ)则先降后升,且均是在N2时达到最大值和最小值,说明适当增加供氮水平可以显著提高米老排幼苗的光合效率;4)200mg·株^(-1)的施氮量最适合米老排幼苗的生长。

To study growth response of Mytilaria laosensis seedlings to nitrogen supply, growth perform- ance and chlorophyll fluorescence of the seedlings were investigated under five nitrogen levels： 100,200, 400,600,and 800 mg per seedling. The results showed that 1） height,ground diameter and total biomass of the seedlings increased initially, and then decreased with the increase of nitrogen supply, compared with the control,they all reached the maximum （40.52 cm,4. 98 mm,and 4.07 g） under the nitrogen level of 200 mg/plant,and increased by 145.7% ,152.8% and 158.4% ,respectively. 2） The nitrogen fertilization could significantly enhance the chlorophyll contents of the seedlings. 3） The maximum photochemical efficiency of PS Ⅱ （Fv/Fm）, the actual photosynthetic efficiency （ФPSⅡ） and photochemical quenching （qP） all showed a trend of initial increase followed by decrease with the increase of nitrogen supply, while the non-photo- chemical quenching （NPQ） presented an opposite trend,their maximum and or minimum values all were in the nitrogen level of 200 mg per seedling, suggesting that the appropriate nitrogen supply could significant- ly promote the photosynthetic efficiency of M. laosensis seedlings. 4） As a whole,200 mg N/seedling was the most appropriate level of nitrogen supply to promote seedling growth of this species.