Seedling growth and photosynthetic response of Pterocarpus indicus L. to shading stress

ABSTRACT

In tropical forests, the shade provided by tree canopies and extreme climate causes inhibition of plant seedling growth due to the lack of light. However, the plants can acclimate to such environmental stress by generating specific responses. The present study aimed to investigate the effects of shading conditions on ecophysiological performance of Narra seedlings (Pterocarpus indicus L.) via a mesocosm experiment. A pot experiment was conducted for 20 weeks in a greenhouse with different shading treatments, 75% (control), 25%, and 4% of full sunlight (FS). As a result, the photosynthetic rate (P_N), Rubisco enzyme activity, maximum carboxylation rate (V_Cmax), and maximum electron transport rate (J_max) in 25% FS treatment were higher or similar to those in control after three weeks of the beginning of shade treatment, whereas the highest values after ten weeks were observed in control. In contrast, the photosynthetic pigments were highest in control after three weeks, while the values were highest in 25% FS treatment after ten weeks. The growth parameters, such as biomass and leaf area, were highest in 75% FS treatment. The expression of Rubisco, phosphoglycerate kinase, glyceraldehyde-3-phosphate dehydrogenase, and fructose-1,6-bisphosphatase were up-regulated in 4% FS treatment compared to control after ten weeks, contributing to tolerating the shade stress. Our findings indicated the capacity of P. indicus seedlings to tolerate and acclimate low light conditions causing shade stress by generating specific physiological and morphological responses, especially Rubisco enzyme activity as well as gene expression related to photosynthetic activity. The present study will improve our understanding of the tolerance mechanism of Narra plant under light-deficient conditions, thereby providing a better strategy for efficiently growing seedlings of this species in tropical rainforests.

KEYWORDS:

• Tropical legume tree
• light deficiency
• Rubisco enzyme activity
• photosynthetic genes
• shade tolerance

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contributions

Conceptualization: K-AL, SYW. Formal analysis and investigation: K-AL, VK, Y-NK. Writing – original draft preparation: K-AL, VK. Writing – review and editing: Y-NK, YBL. Supervision: SYW. All authors read and approved the final manuscript.

Data availability statement

The original datasets presented in the study are available from the corresponding authors.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15592324.2023.2245625

Additional information

Funding

This work was supported by the 2023 Research Fund of the University of Seoul.