白草光合蒸腾日变化及其与气象因子的关系

目的]探讨气象因子对白草光合生理特性的影响。方法]以生长良好的白草植株的健康叶片为材料,采用Li-6400便携式光合系统仪对其进行活体测定,研究白草光合速率和蒸腾速率的日变化及其与气象因子的关系。结果]白草为C4植物,无光合午休现象,其光合速率和蒸腾速率的日变化均为单峰曲线,光合速率最高值出现在12：00,蒸腾速率最高值出现在14：00;白草的净光合速率与光照强度呈极显著正相关,而与相对湿度、气温及叶温的相关性不显著;白草蒸腾速率与气温及叶温呈显著正相关,与光强呈极显著正相关,而与相对湿度呈显著负相关。结论]白草的最佳浇水时间为1d中的10：00和18：00。

Diurnal Variations of Photosynthesis and Transpiration of Pennisetum centrasiaticum Tzvel and Their Relationships with Meteorological Factors

Objective] The aim was to study the effects of meteorological factors on photosynthetic physiological characteristics of Pennisetum centrasiaticum Tzvel.Method] With healthy leaves from good p.centrasiaticum plants as the materials,their vivo detection was conducted with Li-6400 portable photosynthesis system to study the diurnal variations of their photosynthetic rate and transpiration rate and their relationships with meteorological factors.Result] P.centrasiaticum were C4 plants and they had no midday depression of photosynthesis.The diurnal variations of photosynthetic rate and transpiration rate of P.centrasiaticum were all single peak curve,and the highest value of photosynthetic rate appeared at 12:00 am and that of transpiration rate appeared at 14:00 pm.The net photosynthetic rate of P.centrasiaticum had very significant positive correlation with light intensity,but it had no obvious correlation with relative humidity,temperature and leaf temperature.The transpiration rate of P.centrasiaticum had significant positive correlation with temperature and leaf temperature,and it had very significant positive correlation with intensity,but it had significant negative correlation with relative humidity.Conclusion] The optimum irrigation time for P.centrasiaticum was 10:00 am and 18:00 pm in 1 d.