The Impact of Different Stubble Heights on the Photosynthetic Characteristics and Water Use Efficiency of the Sand-Fixing Plant Haloxylon ammodendron
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.
万方数据
维普
