禁牧休牧短花针茅草原主要植物种光合特性研究

Effects of fencing and delaying grazing on photosynthetic characteristics of dominant plant species in the Stipa breviflore grassland

运用Li-6400光合测定仪对禁牧休牧下短花针茅荒漠草原主要种群植物光合特性进行了初步研究。结果表明:1)短花针茅、无芒隐子草和碱韭的净光合速率、蒸腾速率和气孔导度日变化为双峰型,"午休"现象均出现在13:00。2)禁牧休牧下,三种牧草叶片胞间CO2浓度的日变化规律均为"V"字型,在13:00达到最低值。3)休牧2区,三种牧草的净光合速率、蒸腾速率和胞间CO2浓度日均值最大,显著高于禁牧区、自由区、休牧1区和休牧3区(P<0.05)。4)光合生理指标与光合有效辐射、大气温度、大气相对湿度有显著相关关系(P<0.05)。

Effects of fencing and delaying grazing on photosynthetic characteristics of dominant plant species in the Stipa breviflore grassland were investigated using Li-6400 photosynthesis analyzer in this study.The results were shown as follows： 1） The change trends of net photosynthetic rate,transpiration rate and stomatal conductance of Stipa breviflora,Cleistogenes songorica and Allium polyrhizum were bimodal,and ＂siesta＂ phenomenon were presented in the 13：00 point;2） Under fencing and delaying grazing,the three kinds of grass leaf intercellular CO_2 concentration in the diurnal variation were ＂V＂-shape,and reached to the minimum value at 13：00;3） The values of net photosynthetic rate,transpiration rate and intercellular CO_2 concentration of the three kinds of grass leaf in the second delaying grazing polt were high,which were significantly higher than that in the plots of fencing,free grazing,and the first and third delaying grazing plots（P 0.05）;4） There were significant correlations between photosynthetic physiological indicators and photosynthetic active radiation,air temperature,and atmospheric relative humidity（P 0.05）.