氮素添加对草原不同冠层植物光合作用的影响

doi:10.7522/j.issn.1000-694X.2018.00005

摘要/Abstract

摘要： 氮沉降对植物的生理生态特征具有重要影响，草原不同冠层植物光合特性对氮沉降的响应不同。通过向内蒙古典型草原人工施加氮肥模拟氮沉降，测定上层代表性植物羊草（Leymus chinensis）及下层代表性植物黄囊苔草（Carex korshinskyi）的光合速率（P_n）、水分利用效率（WUE）、蒸腾速率（Tr）和气孔导度（G_s）等光合特性指标及生物量，分析氮沉降对草原不同冠层植物的影响。结果表明：羊草净光合速率随着氮添加量增加呈先上升后下降趋势，而黄囊苔草净光合速率随着氮添加量增加呈上升趋势。氮添加增加了羊草的水分利用效率、生物量和相对生物量，但是对黄囊苔草的水分利用效率、生物量和相对生物量没有影响。在施氮量高于0.8 mol·m^-2后，黄囊苔草的气孔导度和蒸腾速率极显著高于羊草（P<0.01）；整体上看，随着氮添加梯度黄囊苔草蒸腾速率呈现增加的趋势，而羊草的气孔导度和蒸腾速率的变化没有明显的规律。典型草原区不同冠层植物的光合特性对氮添加具有不同的响应，上层植物对下层植物光合作用的限制较小。

关键词: 氮沉降, 典型草原, 光合速率, 水分利用效率, 蒸腾速率, 气孔导度

Abstract: Nitrogen deposition plays an important role in shaping the physiological and ecological characteristics of plants. The photosynthetic characteristics of plants in different canopy may respond differently to nitrogen deposition, however the effects remain unclear. By addition urea in Inner Mongolia grassland, we studied the responses of net photosynthesis rate (P_n), water use efficiency (WUE), transpiration rate (Tr), stomatal conductance (G_s) and biomass of two dominant species (Leymus chinensis represents the upper layer species, Carex korshinskyi, represents the lower layer species) to nitrogen deposition. The results showed that P_n of L. chinensis increased with the increase of nitrogen addition, however decreased when the N addition rate above 1.6 mol·m^-2. P_n of C. korshinskyi increased with the increase of nitrogen addition constantly. Nitrogen addition increased the WUE, biomass and relative biomass of L. chinensis, but did not affect the WUE, biomass and relative biomass of C. korshinskyi. The G_s and Tr of C. korshinskyi were significantly higher than those of L. chinensi when the nitrogen addition rate was higher than 0.8 mol·m^-2 (P<0.01). Tr of C. korshinskyi increased with the increase of nitrogen addition, however G_s and Tr of L. chinensis showed no clear pattern. Our results indicated that P_n of lower canopy plant increased constantly with the increase of N addition, implying that the upper plant may have no restrictions on the photosynthesis of the lower plant in arid and semi-arid grasslands.

Key words: nitrogen deposition, typical steppe, net photosynthetic rate, water use efficiency, transpiration rate, stomatal conductance

中图分类号:

Q948.11

徐翀, 庾强, 左小安, 张春萍, 牛得草. 氮素添加对草原不同冠层植物光合作用的影响[J]. 中国沙漠, 2019, 39(1): 135-141.

Xu Chong, Yu Qiang, Zuo Xiaoan, Zhang Chunping, Niu Decao. Effects of Nitrogen Addition on Photosynthetic Characteristics of Different Canopy Plants in Grassland[J]. Journal of Desert Research, 2019, 39(1): 135-141.

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