Effects of Low Light Environment on the Growth and Photosynthesis of Calamus nambariensis Seedlings

The morphological growth and photosynthetic characters of Calamus nambariensis seedlings in response to different light intensities were studied in the laboratory by means of applying shadingnets and artificial daylight lamps with five light intensity gradients (L1:3200 lx, L2:1954 lx, L3:1255 lx, L4:650 lx, L5:350 lx) to understand the effects of low light environment on the growth and photosynthesis of the plant species. The results indicated that the plant height, leaf length, basal diameter and the fresh biomass of the seedlings under L2 light intensity treatment were significantly higher than those of L3, L4 and L5, treatments, but the basal diameter and fresh biomass indexes were lower than those of obtained under L1. With the decline in light intensity, the growth of height and leaf length increased at the initial stage and then decreased, while the growth of basal diameter and fresh biomass kept declining. The contents of chlorophyll a, b and a+b were high under L1 and L2 treatments, then the Chl a/b content dropped as the light intensity decreased. The maximum net photosynthetic rate, apparent quantum efficiency, dark respiration rate, light compensation point and light saturation point indexes dropped to different extent along with the decrease of light intensity, and the above five photosynthetic indexes under the L1 and L2 light treatments were all higher than those of under L3, L4 and L5 light treatments. Comprehensively speaking,Calamus nambariensis could tolerate a certain degree of shading at its seedling stage. The experiment showed that 1 954 lx of light intensity was the lowest limit of light stress for Calamus nambariensis seedlings.