Lower Light Intensities Increase Shoot Germination with Improved Leaf Biosynthesis in Ma Bamboo (Dendrocalamus latiflorus Munro)

Abstract

Ma bamboo (Dendrocalamus latiflorus Munro) is a major bamboo species cultivated in southern China with high economic, ecological, and social value. However, highly dense forests and reasonable structures in bamboo forests have unclear and adverse effects on light transmittance and forest productivity that are not adequately understood. Here, we investigated varied light-intensity treatments during different phases of shoot emergence and development on Ma bamboo shoots. The amount of total chlorophyll, carotenoids, gas exchange indicators, and biosynthetic products were also compared to explore the response mechanism of shoot germination on downstream biochemical pathways. We found that compared to the L0 treatment (full sunlight), the number of germinated bamboo shoots under the L1 treatment (40% light) increased significantly by 44.07% and 101.32% in the shooting initial-phase and metaphase, respectively (p < 0.05). Additionally, the net photosynthetic rate (Pn) during the shooting initial-phase and metaphase was the highest in the L1 treatment, while the L4 (10% light) and L0 treatments inhibited chlorophyll synthesis. Further, the accumulation of leaf carbon (C) and nitrogen (N) was higher in the L1 treatment than in other treatments. Ma bamboo showed rich carbohydrate contents under L0 and L1 treatments in the shooting initial-phase and metaphase. Principal component analysis (PCA) also revealed that the L1 treatment positively correlated with bamboo shoot germination and biochemical activity during the shooting periods. Ultimately, our data suggest that the L1 treatment is the most optimal for promoting bamboo shoot germination, providing a scientific basis for cultivating shoot-used bamboo forests in southern China.