白刺幼苗芽库及枝系构型对不同氮添加水平的响应

目的]研究不同氮添加梯度下白刺幼苗芽库组成及空间结构的差异,探讨了幼苗的养分限制、氮素利用以及根系和插穗的品质与芽库的关联,阐明了白刺芽库响应氮素有效性所采取的适应性策略。方法]本研究通过盆栽控制实验,对唐古特白刺幼苗的芽库特征进行了测量分析。结果]氮添加显著增加了白刺幼苗芽和营养枝数量,显著降低了休眠芽和休眠枝数量,并对二级枝和三级枝出芽率具有明显促进作用;随着氮添加量的递增,营养枝有从基部向顶端移动趋势;氮平衡指数与白刺幼苗出芽强度、分枝强度、二级枝和三级枝出芽率均呈二次非线性正相关关系;植株氮含量、氮积累量和地下部分形态特征分别与芽和营养枝数量呈正相关关系,与休眠芽和休眠枝数量呈负相关关系。结论]氮添加影响幼苗芽库容量。随着氮添加水平的提高,各指标多数在N3和N4处理达到最大值后逐渐降低,因此6个氮添加水平中36 mmol·L-1和48 mmol·L-1是白刺幼苗最适氮添加量。氮添加对幼苗芽库内组分的相对位置产生了不同影响趋势,所以白刺幼苗可以通过改变芽库容量和空间分布来响应养分有效性变化。

Effects of Different Nitrogen Addition on Bud Bank Traits and Branching Architecture of Nitraria tangutorum Seedlings

Objective] To investigate the differences in the composition and spatial structure of bud bank of Nitraria tangutorum seedling under the different nitrogen addition gradients, and nutrient limitation and nitrogen utilization, and to reveal the linkage between the quality of roots and cuttings and the bud bank, and finally elucidate the adaptation strategies of bud bank for the nitrogen availability. Method] The bud bank traits of N. tangutorum seedlings under different nitrogen addition were studied using pot experiments. The N addition levels consist of 0, 12, 24, 36, 48 and 60 mmol·L^-1. Result] The nitrogen addition significantly increased the number of buds and vegetative shoots in bud bank, and significantly reduced the number of dormant buds and dormant shoots; meanwhile, the nitrogen addition promoted the bud production of secondary shoots and tertiary shoots. With the increasing of nitrogen addition, the relative position of vegetative shoots in bud bank had a tendency to move from base to tip. There was a quadratic nonlinear positive correlation between nitrogen balance index (NBI) and budding intensity, branching intensity, bud production of secondary and tertiary shoots of N. tangutorum seedling; The N content, accumulation amount (NAA) and the morphological traits underground were positively related to the number of buds and vegetative shoots, and negatively related to the number of dormant buds and dormant shoots. Conclusion] Among the six nitrogen addition gradients, most of the indicators reached their maximum values in either 36 mmol·L^-1 or 48 mmol·L^-1 N addition levels, which were the optimum N additions for N. tangutorum seedlings. Nitrogen addition has a significantly influence on the bud bank size and spatial distribution of N. tangutorum seedlings, which also reflects a response to the changing nutrient availability.