采用Li-6400光合系统测定方法和盆栽苗木称重法,分别对华南石灰岩地区特有树种任豆Zenia insignis以及2种石灰岩地区造林供选树种石斑木Rhaphiolepis indica和楝叶吴茱萸Evodia glabrifolia光合特性和蒸腾耗水日变化规律进行比较.结果表明:在苗木生长旺盛时期,与任豆相比,石斑木和楝叶吴茱萸具有相近甚至更佳的光合生长能力和节水性能；光合特性方面,正常条件下3种苗木净光合速率日变化曲线均呈“双峰型”,1d中最高净光合速率石斑木最高,达到(11.709 ±0.392) μmol·m-2·s-1,楝叶吴茱萸次之,任豆最低；光响应曲线特征参数值显示石斑木光合生长能力最强,任豆和楝叶吴茱萸相近；耗水特性方面,任豆昼夜耗水量显著高于石斑木和楝叶吴茱萸,白天耗水量约占全天耗水量的90％,3种苗木的最大耗水速率相对较小,介于2.91×10-4 ～4.28×10-4mol· m-2·s-1,其中楝叶吴茱萸的最大耗水速率低于任豆,而石斑木略高于任豆,并且3种苗木最大耗水速率与白天平均耗水速率的平均比值约为1.6.%Daily variations in photosynthesis and water-consumption in the seedlings were compared a-mong three species by using Li-6400 photosynthetic system and by weighting potted seedlings. The experimental species included an endemic tree species (Zenia insignis) distributed in limestone area in south China and two other tree species ( Evodia glabrifolia, Rhaphiolepis indica) commonly used for afforestation in limestone area. The results showed that R. indica and E. glabrifolia had similar or better ability to grow through photosynthesis and water conservation as compared with Z. insignis in vigorous growth periods. As for photosynthetic characteristics, the daily variation trend of net photosynthetic rate of seedlings from the three species was a "twin peaks" curve. R. indica had the highest net photosynthetic rate, reaching (11. 709 ± 0. 392) μmol · m-2 · s-1 E. glabrifolia took second place, and Z. insignis was at the lowest level. The parameter values on photoresponse curve indicated that R. indica had the most powerful ability to grow through photosynthesis, while Z. insignis and E. glabrifolia were similar to each other. As for the characteristic of water-consumption, the water-consumption in daytime and nighttime of Z. insignis was significantly higher than those of R. indica and E. glabrifolia. Water-consumption in daytime accounted for about 90% of the total consumption in the whole day. The water-consumption rate of the three species seedlings was comparatively low, between 2. 91 ×l0-4 -4.28 × 10 -4 mol · m-2 · s-1. Maximum water-consumption rate of E. glabrifolia was the lowest among them, while that of R. indica was slightly higher compared with Z. insignis, and the average ratio of the maximum water-consumption rate and the average water-consumption rate was about 1.6.
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