Leaf chlorophyll parameters and photosynthetic characteristic variations with stand age in a typical desert species ( Haloxylon ammodendron )

• Published in: Frontiers in plant science 2022-10, Vol.13, p.967849
• Main Authors: He, Xiao-Hui, Si, Jian-Hua, Zhou, Dong-Meng, Wang, Chun-Lin, Zhao, Chun-Yan, Jia, Bing, Qin, Jie, Zhu, Xing-Lin
• Format: Article
• Language: English
• Subjects: Haloxylon ammodendron; leaf chlorophyll parameters; maximal net photosynthetic rate (Pnmax); maximum light energy use efficiency (LUEmax); Plant Science; stand age
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2022.967849

As a desert shrub, combines ecological, economic, and social benefits and plays an important role in the ecological conservation of arid desert areas. Understanding its physiological characteristics and its mechanism of light energy utilization is important for the conservation and utilization of . Therefore, we selected five stands (5-, 11-, 22-, 34-, and 46-year-old) of as research objects in the study and measured their photosynthetic light response curves by a portable open photosynthesis system (Li-6400) with a red-blue light source (6400-02B). Then, we measured the leaf chlorophyll parameters in the laboratory, calculated the photosynthetic characteristics by using Ye Zipiao's photosynthetic model, analyzed their variation patterns across stand ages, and explored the relationships between leaf chlorophyll parameters and photosynthetic characteristics. The results showed that leaf chlorophyll parameters and photosynthetic characteristics of at different stand ages were significantly different. Chl content, , and LUE of were V-shaped with the increase of stand age. The 5-year-old was in the rapid growth period, synthesized more Chl content (8.47 mg g ) only by using a narrower range of light, and the and LUE were the highest with values of 36.21 μmol m s and 0.0344, respectively. For the 22-year-old , due to environmental stress, the values of Chl content, , and LUE were the smallest and were 2.64 mg g , 25.73 μmol m s , and 0.0264, respectively. For the older , its Chl content, , and LUE were not significantly different and tended to stabilize but were slightly higher than those of the middle-aged . On the other hand, the other photosynthetic parameters did not show significant variation patterns with stand age, such as , AQE, LSP, LCP, and . In addition, we found that the relationships between Chl content and and between Chl content and LUE were highly correlated, except for the older . Thus, using leaf chlorophyll content as a proxy for photosynthetic capacity and light use efficiency should be considered with caution. This work will provide a scientific reference for the sustainable management of desert ecosystems and vegetation restoration in sandy areas.