[Response of seed germination and seedling growth of Chinese fir to different light intensities]

Abstract

The effect of light intensity on the seed germination and seedling growth of Chinese fir under different light intensities (100%, 40%, 20%, 10%, 5% of full light, and the PPFD was 201.3, 77.0, 37.5, 19.2, 9.8 μmol·m^-2·s^-1, respectively) was investigated, and the adaptive strategy of seed germination, seedling survival, growth, morphological plasticity, biomass accumulation and allocation under different light intensities was explored in this paper. The results showed that light intensity significantly affected the germination rate, survival rate, establishment rate and germination index. Germination rate reached the maximum under 40% light intensity, while survival rate and establishment rate reached the maximum at 100% light intensity. With the light intensity decreased, the stem length increased, while the root length, cotyledon length, cotyledon thickness and euphylla number declined, and basal stem diameter had no significant difference among diffe-rent light intensities. The total biomass, root biomass, stem biomass and leaf biomass were the highest under 100% light intensity. With the light intensity decreased, the photosynthesis non-photosynthesis biomass ratio and leaf biomass ratio declined, while stem biomass ratio increased, the root to shoot ratio and root biomass ratio had no significant difference among different light intensities. Low light promoted seed germination, but seedlings grew slowly with high mortality under low light. The accumulation of biomass in stem increased the plant tolerance to low light.

Keywords: Chinese fir; biomass allocation; morphological plasticity; natural regeneration; seedling emergence; shade.