Chin J Plant Ecol ›› 2022, Vol. 46 ›› Issue (1): 88-101.DOI: 10.17521/cjpe.2021.0206

Special Issue: 光合作用

• Research Articles • Previous Articles     Next Articles

Effects of ramet ratio on photosynthetic physiology of Indocalamus decorus clonal system under heterogeneous light environment

Li-Ting YANG, Yan-Yan XIE, Ke-Yi ZUO, Sen XU, Rui GU, Shuang-Lin CHEN, Zi-Wu GUO()   

  1. Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou 311400, China
  • Received:2021-05-31 Accepted:2021-10-08 Online:2022-01-20 Published:2022-04-13
  • Contact: Zi-Wu GUO
  • Supported by:
    the National Natural Science Foundation of China(31770447)


Aims Differences in number of ramets or biomass ratio might have remarkable effects on the adaptability of plant clonal systems to resource heterogeneity. Connected-ramets of bamboo, with lignified rhizomes, usually grow in heterogeneous light environment, but little is known about the response of photosynthetic physiological characteristics in the ramet leaves to heterogeneous light environment and the effects of ramet ratio. Methods The clonal system with four-connected ramets of Indocalamus decorus was grown in the two different shading rates (50% ± 5% and 75% ± 5%) and in the three levels of ramet ratios (the ratios of shaded to unshaded ramets are 1:3, 2:2 and 3:1, respectively). The light response characteristics, gas exchange parameters and photosynthetic pigment content of shaded and unshaded ramets under heterogeneous light conditions were measured at 30, 90 and 150 days after shading treatment, respectively. Important findings The ramet ratio, and its interaction with shading and treatment time had significant effects on photosynthetic physiology of I. decorus. With the increase in the proportion of shaded ramets, leaves apparent quantum efficiency (AQE), light saturation point, maximum net photosynthetic rate (Pn max), net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and water use efficiency increased, but light compensation point and dark respiration rate decreased, indicating higher photosynthetic efficiency and light utilization of shaded ramets, whereas the reverse was true for connected unshaded ramets. Furthermore, leaves chlorophyll a and chlorophyll b contents of the shaded ramets firstly increased and then decreased, while both the carotenoid content of shaded ramet and photosynthetic pigment (chlorophyll a, chlorophyll b and carotenoid) contents of the unshaded ramets all decreased continuously. Besides, under the same ramet ratio, AQE, Pn max, Pn, Gs, Ci and photosynthetic pigments content of leaves in shaded ramets increased with the increment of shading rate, while leaves Pn max, Ci and carotenoid contents of the unshaded ramets decreased. Our results indicated that photosynthetic efficiency and light utilization of shaded ramets significantly increased in the heterogeneous light environment, whereas the reverse was true for unshaded ramets. These exhibited obvious division of labor in the clonal system, and ramet ratio of 2:2 and 3:1 showed the better adaptability to heterogeneous light environment than that of 1:3. Therefore, those findings highlighted I. decorus could largely enhance the fitness of the clonal system to adapt to the heterogeneous light environment by modifying the leaf photosynthetic physiology and photosynthetic pigments content, which improved the light utilization and photosynthetic efficiency of the shaded ramets.

Key words: Indocalamus decorus, ramet ratio, heterogeneous light environment, photosynthetic physiology, physiological integration, clonal plant