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.

Biostimulatory Effects of Chlorella fusca CHK0059 on Plant Growth and Fruit Quality of Strawberry

“…According to our previous analysis of C. fusca CHK0059 cell composition, it contained high levels of N (91.2 g kg −1 ), P (9.38 g kg −1 ), K (2.62 g kg −1 ), Ca (1.05 g kg −1 ), Mg (5.85 mg kg −1 ), etc., inferring that added Chlorella is likely to be well absorbed as a nutrient source for strawberry plants. In addition, the improved nutritional status of the plants appeared to positively influence the photosynthetic capacity by regulating their morphological characteristics, such as specific leaf area and leaf mass ratio, that are highly related to the efficiencies of light capture and carbon gain [ 32 , 33 ]. A similar research result has also been reported by Kim et al [ 26 ], who demonstrated significant increases in shoot height, leaf thickness, and leaf pigments of the strawberry cultivar ‘Seolhyang’ by C. fusca CHK0059 application.…”