杨树幼苗非结构性碳水化合物对增加降水和氮添加的响应

设置3个水分梯度,即自然降水(W₁)、自然降水增加50%(W₂)和增加100%(W₃)以及4个施氮梯度,即模拟氮沉降添加0(N₁)、5(N₂)、10(N₃)和15(N₄) g N·m^-2·a^-1,研究增加降水和氮添加对杨树幼苗非结构性碳水化合物(NSC)的影响.结果表明: 增加降水和氮添加对杨树幼苗NSC含量具有显著的交互作用.随着降水的增加,N₁水平叶片和枝条可溶性糖含量不变,叶片、枝条、主干、粗根和细根淀粉含量下降;N₂和N₃水平各器官可溶性糖含量下降或保持不变,淀粉含量降低或先升高后降低;N₄水平各器官可溶性糖和淀粉含量升高或先降低后升高.随着氮沉降的增加,W₁处理叶片可溶性糖含量不变,淀粉含量增加,细根可溶性糖含量增加,淀粉含量不变;W₂处理各器官可溶性糖含量不变或先增加后减少,淀粉含量降低或先增加后降低;W₃处理各器官可溶性糖、淀粉和NSC含量均增加.各水分和施氮梯度处理下,杨树幼苗可溶性糖含量为39.1～88.3 mg·g^-1,叶片中最高,细根中最低,淀粉含量为23.3～46.8 mg·g^-1,粗根中最高,细根中最低.

Responses of non-structural carbohydrates of poplar seedlings to increased precipitation and nitrogen addition.

To understand the effects of precipitation increase and nitrogen addition on non-structural carbohydrates (NSC) of poplar seedlings, Populus × xiaozhuanica cv. Zhangwu seedlings were grown under a full factorial experimental design of two factors, i.e., three water treatments (W₁,natural precipitation; W₂, natural precipitation increased by 50%; W₃, increased by 100%) and four N fertilization levels (N₁,0 g N·m^-2·a^-1; N₂,5 g N·m^-2·a^-1; N₃,10 g N·m^-2·a^-1; N₄,15 g N·m^-2·a^-1). The results showed that changes in NSC contents in each organ of P. Zhangwu seedlings reflected significant interactions between precipitation increase and nitrogen addition. With the increase of precipitation, under the N₁ level, soluble sugar content was unchanged in leaves and branches, while the starch content decreased in leaves, branches, stems, coarse and fine roots. With the increase of precipitation, the soluble sugar content remained unchanged or declined, while the starch content decreased or firstly increased and then decreased in different organs under the N₂ and N₃ levels. The soluble sugar and starch contents increased or firstly decreased and then increased in different organs under the N₄ level. With the increase of N addition, the soluble sugar content remained unchanged and the starch content increased in leaves, soluble sugar content increased and starch content was unchanged in fine roots in the W₁ treatment. The soluble sugar content remained unchanged or firstly increased and then decreased, and the starch content decreased or firstly increased and then decreased in different organs in the W₂ treatment. The soluble sugar, starch and NSC contents increased in the W₃ treatment. In different precipitation and N addition treatments, the soluble sugar contents of P. Zhangwu seedlings ranged from 39.1 to 88.3 mg·g^-1, with the highest value observed in leaves and the lowest value in fine roots, and the starch content ranged from 23.3 to 46.8 mg·g^-1, with the highest in coarse roots and the lowest in fine roots.