水保所知识产出(1956---)知识库

目的】氮素和水分是干旱半干旱区生态系统的主要限制因子，研究两者交互作用对干旱半干旱区植物
碳 (C)、氮 (N)、磷 (P) 化学计量特征的影响有助于深入了解干旱半干旱生态系统对全球变化的响应。
【 方法】以黄土丘陵区退耕地典型草本植物白羊草 (Bothriochloa ischaemum) 为研究对象，采用盆栽控制试验，
设置添加氮 0(对照)、2.5 g/(m 2 ·a)(低氮)、5.0 g/(m 2 ·a)(高氮) 三个水平；供水处理设 75%～80% FC (充分供水)、
55%～60% FC (轻度干旱胁迫) 和 35%～40% FC (重度干旱胁迫) 三个水平。测定了白羊草地上部分和根系碳氮
磷含量，讨论了氮素和水分供应对其化学计量特征的影响。 【 结果】氮素添加和干旱胁迫对白羊草地上部分和
根系碳含量无显著影响，氮素添加使白羊草地上部分氮含量提高 9.7%～48.8% (P < 0.001)，而干旱胁迫使其降
低 2.8%～28.3% (P < 0.001)。氮素添加和干旱胁迫对白羊草根系氮含量的影响表现为正常水分条件下氮素添加
使根系氮含量提高 25.0%～26.1% (P < 0.01)，而干旱条件下氮素添加无显著作用。氮素添加和干旱胁迫使白羊
草地上部分磷含量分别降低 17.4%～31.8% 和 12.0%～22.1% (P < 0.001)。氮素添加和干旱胁迫对白羊草地上部
分 C∶N 的影响表现为在干旱胁迫条件下氮素添加使地上部分 C∶N 降低 24.9%～32.9% (P < 0.05)，在正常供水
条件下氮素添加无显著影响。氮素添加对根系部分 C∶N 有显著影响，在正常供水条件下氮素添加使根系部分
C∶N 降低 19.8%～24.5% (P < 0.05)。氮素添加和干旱胁迫使白羊草地上部分 C∶P 分别提高 24.4%～42.3% 和
12.2%～31.0% (P < 0.001)，对根系 C∶P 无显著影响。氮素添加显著提高白羊草地上部分 N∶P，干旱胁迫对白
羊草地上部分 N∶P 无显著影响。氮素添加和干旱胁迫对白羊草根系部分 N∶P 表现为在正常供水条件下氮素添
加使根系部分 N∶P 提高 26.8%～54.8% (P < 0.05)，在干旱胁迫条件下氮素添加无显著影响。 【 结论】氮素添
加条件下白羊草 C∶P 和 N∶P 的提高表明氮沉降增加一定程度上改善了土壤供氮状况，进一步加剧了磷素限制
作用。氮素增加条件下干旱胁迫对 N∶P 无显著影响，表明白羊草的生长将逐渐受到氮素和磷素的共同限制。

Both nitrogen and water shortage are the main limiting factors for plant growth in arid
and semiarid ecosystems. Study the carbon (C), nitrogen (N) and phosphorus (P) stoichiometric characteristics of
plant under nitrogen deposition and drought stress will help understanding the response characteristics of arid and
semiarid ecosystems to global changes. 【Methods】A pot experiment was conducted inside a phytotron using
Bothriochloa ischaemum as tested martials. N application rates of 0, 2.5 and 5.0 g/(m 2 ·a) were designed  representing CK, low N and high N rate; and water supply levels of field capacity of 75%–80%, 55%–60% and
35%–40% were setup, representing drought stress level of well-watered, moderate drought stress and severe
drought stress in turn. The contents of C, N and P in the shoot and root were determined and the C, N, and P
stoichiometry were calculated. 【Results】N addition and drought stress had no significant influence on C
concentration in the aboveground and root of B. ischaemum. N addition increased the N concentration by
9.7%–48.8% (P < 0.001) in the shoot, while drought stress decreased it by 2.8%–28.3% (P < 0.001). Nitrogen
addition and drought stress had significant interactive effects on the root N concentration, N addition increased
the N concentration by 25.0%–26.1% (P < 0.01) under well-watered condition and had no significant influence
on it under drought stress condition. N addition and drought stress significantly decreased the P concentration
by 17.4%–31.8% and 12.0%–22.1% in shoot. N addition and drought stress had significant interactive effects
on the C∶N ratio in shoot, N addition increased the C∶N ratio by 24.9%–32.9% (P < 0.05) under drought
stress, but not under well-watered condition. The C∶N ratio in the root of B. ischaemum was decreased by
19.8%–24.5% (P < 0.05) by N addition under well watered condition. N addition and drought stress decreased the
C∶P ratio by 24.4%–42.3% and 12.2%–31.0% in the shoot of B. ischaemum, respectively, but not in the root. N
addition significantly increased the N∶P ratio in the aboveground part of B. ischaemum, drought stress did not. N
addition and drought stress had significant interactive influence on the N∶P ratio in the root of B. ischaemum, N
addition increased the N∶P ratio by 26.8%–54.8% (P < 0.05) under well-watered condition and had no
significant influence on it under drought stress condition. 【Conclusions】N addition will increase the C∶P and
N∶P ratio in the aboveground part of B. ischaemum under drought stress, intimating that the growth of B.
ischaemum would be restrained by both N and P on the Loess Plateau with the aggravation of drought stress and N
deposition to some extent.