氮素营养对闽楠幼苗生长及光合特性的影响

设置0、50、100、150、200、300、400、600 mg·株-1 8个N处理,通过盆栽试验研究氮素对闽楠苗生长及光合特性的影响.结果表明:随着供氮量的增加,闽楠苗高、地径、叶面积和根、茎、叶及整株生物量均呈现先增加后降低的趋势,其中,苗高、地径和叶面积均在供氮量100 mg·株-1时最高,而各器官生物量及整株生物量均在供氮量150 mg·株-1时最大;根冠比则随着供氮量的增加呈现单调递减趋势;闽楠苗光合特性与生长表现是契合的,随供氮水平的提高,闽楠苗叶绿素a、b及总量先升高后降低,净光合速率、气孔导度、胞间二氧化碳浓度和蒸腾速率值也均呈先仰后抑之势,恰在供氮量100 mg·株-1时,以上光合参数值均达最高,且不同氮素处理间闽楠光合气体交换参数和蒸腾速率差异均显著.综合闽楠苗各生长及光合指标的分析结果,100～150 mg·株-1的供氮量为闽楠苗温室培育的适宜范围.

Effects of Nitrogen Loading on Growth and Photosynthetic Characteristics of Phoebe bournei Seedlings

The growth and photosynthetic characteristics of Phoebe bournei pot seedlings applied with 0, 50, 100, 150, 200, 300, 400, and 600 mg nitrogen per seedling in a greenhouse were investigated. The 100 mg·seedling^-1 level could accelerate the mean height, ground diameter and leaf area growth; the biomass of most organs was the highest for seedling applied with nitrogen at 150 mg per seedling; the ratio of root to shoot decreased with the increasing of nitrogen fertilization; the photosynthetic performance and growth index of P. bournei seedling was consistent, the content of chlorophyll a, chlorophyll b and total chlorophyll increased then decreased with the nitrogen fertilization increased; the net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration and transpiration rate were observed to increase with the increase of nitrogen from 0 to 100 mg per seedling and decrease with further increase of nitrogen fertilization from 100 to 400 mg per seedling. Statistical analysis indicated that the photosynthetic gas exchange parameters and transpiration rate varied significantly under different nitrogen treatments. So it is concluded that 100-200 mg nitrogen per seedling is the appropriate range for seedlings of P. bournei nursed in a greenhouse.