Niu Shuli, Yuan Zhiyou, Zhang Yanfang, Liu Weixing, Zhang Lei, Huang Jianhui, Wan Shiqiang
Laboratory of Quantitative Vegetation Ecology, Institute of Botany, the Chinese Academy of Sciences, Xiangshan, Beijing 100093, China.
J Exp Bot. 2005 Nov;56(421):2867-76. doi: 10.1093/jxb/eri281. Epub 2005 Oct 3.
This study examined the impacts of seasonal water variability and interspecific competition on the photosynthetic characteristics of a C3 (Leymus chinensis) and a C4 (Chloris virgata) grass species. Plants received the same amount of water but in three seasonal patterns, i.e. the one-peak model (more water in the summer than in the spring and autumn), the two-peak model (more water in the spring and autumn than in the summer), and the average model (water evenly distributed over the growing season). The effects of water variability on the photosynthetic characteristics of the C3 and C4 species were dependent on season. There were significant differences in the photosynthetic characteristics of the C4 species in the summer and the C3 species in the autumn among the three water treatments. Interspecific competition exerted negative impacts on the C3 species in August and September but had no effects on the C4 species in any of the four measuring dates. The relative competitive capability of the two species was not altered by water availability. The assimilation rate, the maximum quantum yield of net CO2 assimilation, and the maximum rate of carboxylation of the C3 species were 13-56%, 5-11%, and 11-48% greater, respectively, in a monoculture than in a mixture in August and September. The results demonstrated that the photosynthetic characteristics of the C3 and C4 species were affected by water availability, but the effects varied considerably with season.
本研究考察了季节性水分变化和种间竞争对一种C3植物（羊草）和一种C4植物（虎尾草）光合特性的影响。植株接受相同量的水分，但分为三种季节性模式，即单峰模式（夏季水分多于春季和秋季）、双峰模式（春季和秋季水分多于夏季）和平均模式（整个生长季水分均匀分布）。水分变化对C3和C4植物光合特性的影响取决于季节。在三种水分处理下，夏季C4植物和秋季C3植物的光合特性存在显著差异。种间竞争在8月和9月对C3植物产生负面影响，但在四个测量日期中的任何一个对C4植物均无影响。两种植物的相对竞争能力不受水分可利用性的影响。8月和9月，C3植物在单作时的同化率、净CO2同化的最大量子产量和最大羧化速率分别比混作时高13 - 56%、5 - 11%和11 - 48%。结果表明，C3和C4植物的光合特性受水分可利用性影响，但影响随季节变化很大。
