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. 2021 Feb 4;10(2):294.
doi: 10.3390/plants10020294.

Grazing Intensity Alters Leaf and Spike Photosynthesis, Transpiration, and Related Parameters of Three Grass Species on an Alpine Steppe in the Qilian Mountains

Jin Li  1 , Fujiang Hou  1 , Jizhou Ren  1
Affiliations

Grazing Intensity Alters Leaf and Spike Photosynthesis, Transpiration, and Related Parameters of Three Grass Species on an Alpine Steppe in the Qilian Mountains

Jin Li et al. Plants (Basel). .

Abstract

The effect of grazing on leaf photosynthesis has been extensively studied. However, the influence of grazing on photosynthesis in other green tissues, especially spike, has remained poorly understood. This study investigated the impact of different grazing intensities (light grazing (LG), medium grazing (MG), and heavy grazing (HG)) on leaf and spike photosynthesis parameters and photosynthetic pigments of three grass species (Stipa purpurea, Achnatherum inebrians, and Leymus secalinus) on an alpine steppe in the Qilian Mountains. Grazing promoted leaf photosynthesis rate in S. purpurea and L. secalinus but reduced it in A. inebrians. Conversely, spike photosynthesis rate decreased in S. purpurea and L. secalinus under intense grazing, while there was no significant difference in spike photosynthesis rate in A. inebrians. The leaf and spike net photosynthetic rate (Pn) and transpiration rate (Tr) in S. purpurea were the greatest among the three species, while their organ temperatures were the lowest. On the other hand, grazing stimulated leaf chlorophyll biosynthesis in S. purpurea and L. secalinus but accelerated leaf chlorophyll degradation in A. inebrians. Furthermore, spike chlorophyll biosynthesis was inhibited in the three species under grazing, and only L. secalinus had the ability to recover from the impairment. Grazing had a positive effect on leaf photosynthesis parameters of S. purpurea and L. secalinus but a negative effect on those of A. inebrians. However, spike photosynthesis parameters were negatively influenced by grazing. Among the three species investigated, S. purpurea displayed the greatest ability for leaf and spike photosynthesis to withstand and acclimate to grazing stress. This study suggests that moderate grazing enhanced leaf photosynthetic capacity of S. purpurea and L. secalinus but reduced it in A. inebrians. However, spike photosynthetic capacity of three grass species decreased in response to grazing intensities.

Keywords: alpine steppe; grazing intensity; leaf; photosynthesis parameters; photosynthetic pigments; spike.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Diurnal time course of the photosynthetically active radiation (PAR) (a), air temperature (Ta) (b), and air relative humidity (RH) (c). The data are presented as mean ± standard error (SE) of three independent experiments.
Figure 2
Figure 2
Diurnal dynamics of the net photosynthetic rate (Pn) of the leaves and spikes of S. purpurea (a,d), A. inebrians (b,e) and L. secalinus (c,f) in response to grazing intensity (LG, light grazing; MG, medium grazing; HG, heavy grazing). The data are presented as mean ± standard error (SE) of three independent experiments.
Figure 3
Figure 3
Mean values of photosynthesis parameters including the net photosynthetic rate (Pn) (a), transpiration rate (Tr) (b), water use efficiency (WUE) (c), and leaf temperature (Tl) (d) of the leaves of S. purpurea, A. inebrians and L. secalinus in response to grazing intensity (LG, light grazing; MG, medium grazing; HG, heavy grazing). Note: S. purpurea, Stipa purpurea; A. inebrians, Achnatherum inebrians; L. secalinus, Leymus secalinus. The data are presented as mean ± standard error (SE) of three independent experiments. ** p ≤ 0.01; *** p ≤ 0.001; NS, no significance. Different lowercase letters mean significant difference (p ≤ 0.05) between same species under different grazing intensities. Different uppercase letters mean significant difference (p ≤ 0.05) between different species or different grazing intensities.
Figure 4
Figure 4
Mean values of photosynthesis parameters including the net photosynthetic rate (Pn) (a), transpiration rate (Tr) (b), water use efficiency (WUE) (c), and spike temperature (Ts) (d) of the spikes of S. purpurea, A. inebrians and L. secalinus in response to grazing intensity (LG, light grazing; MG, medium grazing; HG, heavy grazing). Note: S. purpurea, Stipa purpurea; A. inebrians, Achnatherum inebrians; L. secalinus, Leymus secalinus. The data are presented as mean ± standard error (SE) of three independent experiments. ** p ≤ 0.01; *** p ≤ 0.001; NS, no significance. Different lowercase letters mean significant difference (p ≤ 0.05) between same species under different grazing intensities. Different uppercase letters mean significant difference (p ≤ 0.05) between different species or different grazing intensities.
Figure 5
Figure 5
Diurnal dynamics of the transpiration rate (Tr) of the leaves and spikes of S. purpurea (a,d), A. inebrians (b,e) and L. secalinus (c,f) in response to grazing intensity (LG, light grazing; MG, medium grazing; HG, heavy grazing). The data are presented as mean ± standard error (SE) of three independent experiments.
Figure 6
Figure 6
Diurnal dynamics of the water use efficiency (WUE) of the leaves and spikes of S. purpurea (a,d), A. inebrians (b,e) and L. secalinus (c,f) in response to grazing intensity (LG, light grazing; MG, medium grazing; HG, heavy grazing). The data are presented as mean ± standard error (SE) of three independent experiments.
Figure 7
Figure 7
Diurnal dynamics of the leaf temperature (Tl) and spike temperature (Ts) of S. purpurea (a,d), A. inebrians (b,e) and L. secalinus (c,f) in response to grazing intensity (LG, light grazing; MG, medium grazing; HG, heavy grazing). The data are presented as mean ± standard error (SE) of three independent experiments.
Figure 8
Figure 8
Correlations between leaf net photosynthetic rate (Pn) and leaf temperature (Tl) (top), and between spike Pn and spike temperature (Ts) (bottom) of S. purpurea (a,d), A. inebrians (b,e) and L. secalinus (c,f) under grazing intensity (LG, light grazing; MG, medium grazing; HG, heavy grazing).
Figure 9
Figure 9
Correlations between leaf transpiration rate (Tr) and leaf temperature (Tl) (top), and between spike Tr and spike temperature (Ts) (bottom) of S. purpurea (a,d), A. inebrians (b,e) and L. secalinus (c,f) under grazing intensity (LG, light grazing; MG, medium grazing; HG, heavy grazing).
Figure 10
Figure 10
Correlations between leaf water use efficiency (WUE) and leaf temperature (Tl) (top), and between spike WUE and spike temperature (Ts) (bottom) of S. purpurea (a,d), A. inebrians (b,e) and L. secalinus (c,f) under grazing intensity (LG, light grazing; MG, medium grazing; HG, heavy grazing).
Figure 11
Figure 11
Map of study site. (a) Location of study site in Sunan County, the middle part in northern slope of the Qilian Mountains; (b) The grazing land and Gansu wapiti (Cervus elaphus kansuensis).
See this image and copyright information in PMC

References

    1. Luo C., Xu G., Chao Z., Wang S., Lin X., Hu Y., Zhang Z., Duan J., Chang X., Su A., et al. Effect of warming and grazing on litter mass loss and temperature sensitivity of litter and dung mass loss on the Tibetan plateau. Glob. Chang. Biol. 2010;16:1606–1617. doi: 10.1111/j.1365-2486.2009.02026.x. - DOI
    1. Sala O.E., Yahdjian L., Havstad K., Aguiar M.R. Rangeland Systems. Springer; Cham, Switzerland: 2017. Rangeland ecosystem services: Nature’s supply and humans’ demand; pp. 467–489.
    1. Ashraf M., Harris P.J.C. Photosynthesis under stressful environments: An overview. Photosynthetica. 2013;51:163–190. doi: 10.1007/s11099-013-0021-6. - DOI
    1. Guanter L., Zhang Y., Jung M., Joiner J., Voigt M., Berry J.A., Frankenberg C., Huete A.R., Zarco-Tejada P., Lee J.E., et al. Global and time-resolved monitoring of crop photosynthesis with chlorophyll fluorescence. Proc. Natl. Acad. Sci. USA. 2014;111:E1327–E1333. doi: 10.1073/pnas.1320008111. - DOI - PMC - PubMed
    1. Zheng S., Lan Z., Li W., Shao R., Shan Y., Wan H., Taube F., Bai Y. Differential responses of plant functional trait to grazing between two contrasting dominant C3 and C4 species in a typical steppe of Inner Mongolia, China. Plant Soil. 2011;340:141–155. doi: 10.1007/s11104-010-0369-3. - DOI

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