摘要
为了了解不同留茬高度梭梭(Haloxylon ammodendron)的光合特性、水分利用效率及其存在的差异,利用Li-6800便携式光合仪测定了不同光合有效辐射时,不同留茬高度(60、90、120 cm)梭梭的光响应曲线,分析不同留茬高度梭梭的光合特性和水分利用效率.结果表明:在光合有效辐射0～2000 μmol·m-2·s-1范围内,不同留茬高度梭梭的净光合速率、蒸腾速率、气孔导度变化趋势相似,均随着光合有效辐射的增强而增加,胞间CO2摩尔分数呈下降趋势.光合有效辐射大于600μmol·m-2·s-1时,净光合速率从大到小均表现为留茬高度90(14.313μmol·m-2·s-1)、60(12.726 µmol·m-2·s-1)、120cm(9.523 μmol·m-2·s-1)、未处理(6.184 μmol·m-2·s-1),其差异显著(P＜0.05).不同留茬高度梭梭的水分利用效率随着光合有效辐射的增加呈非线性增加,从大到小依次为留茬高度 90(3.093 mmol·mol-1)、60(2.329 mmol·mol-1)、120 cm(2.081 mmol·mol-1)、对照(1.583 mmol·mol-1).留茬高度120 cm梭梭的水分利用效率最低,光合能力最弱;留茬高度60 cm梭梭的水分利用效率中等,光合能力中等;留茬高度90 cm梭梭的光合能力最高,通过降低蒸腾速率而提高水分利用效率,水分利用效率最高.
Abstract
In order to understand the photosynthetic characteristics,water use efficiency,and differences among Haloxylon am-modendron at different stubble heights,the Li-6800 portable photosynthesis system was used to measure the light response curves of H.ammodendron at stubble heights of 60 cm,90 cm,and 120 cm under various photosynthetically active radia-tion levels.The photosynthetic characteristics and water use efficiency of H.ammodendron at different stubble heights were analyzed.The results showed that within the photosynthetically active radiation range of 0 to 2 000 μmol·m-2·s-1,the net photosynthetic rate,transpiration rate,and stomatal conductance of H.ammodendron at different stubble heights exhib-ited similar trends,increasing with the enhancement of photosynthetically active radiation,while the intercellular CO2 mole fraction showed a decreasing trend.When the photosynthetically active radiation exceeded 600 μmol·m-2·s-1,the net photosynthetic rate was highest at a stubble height of 90 cm(14.313 μmol·m-2·s-1),followed by heights of 60 cm(12.726pamol·m-2·s-1)and 120 cm(9.523 μmol·m-2·s-1),with the untreated control displaying the lowest rate(6.184 μmol·m-2·s-1),with significant differences(P＜0.05).The water use efficiency of H.ammodendron at different stubble heights showed a non-linear increase with the rise in photosynthetically active radiation,ranking highest to lowest as follows:90 cm(3.093 mmol·mol-1),60 cm(2.329 mmol·mol-1),120 cm(2.081 mmol·mol-1),and the control(1.583 mmol·mol-1).H.ammodendron at a stubble height of 120 cm exhibited the lowest water use efficiency and wea-kest photosynthetic capacity,while at a height of 60 cm,both water use efficiency and photosynthetic capacity were moder-ate.H.ammodendron at a stubble height of 90 cm demonstrated the highest photosynthetic capacity,achieving increased water use efficiency by reducing transpiration rate,thus resulting in the highest water use efficiency.
维普
万方数据