Effects of light intensity on Quercus liaotungensis seed germination and seedling growth

This paper studied the effects of different shading(55.4%,18.9%,5.5%,2.2%,0.5%,and 0.3% natural sunlight) on the seed germination and seedling growth of Quercus liaotungensis.The seed germination rate and germination index were the highest(72.5% and 0.22,respectively) at 55.4% natural sunlight,declined with decreasing light intensity,and were the lowest(42.5% and 0.11,respectively) at 0.3% natural sunlight.Strong light had definite delaying effect on the germination.The index of germination vigor increased with decreasing light intensity,being the maximum at 0.5% natural sunlight.The delay of seed germination under strong light could be the selective tradeoff on varied seed fates. Strong light benefited the basal stem diameter and root system growth and dry mass accumulation of Q.liaotunensis seedling,but resulted in the minimum seedlings height(6.06 cm).Greater morphological plasticity was observed for the seedlings under different shading,which lent support to the higher adaptability of the seedlings to light environment.For example,the specific leaf area,specific shoot length,specific root length,and chlorophyll b and total chlorophyll contents were the maximum at 0.5% natural sunlight,being 142.57 cm2·g-1,156.86 cm·g-1,271.87 cm·g-1,0.07 g·cm-2,and 0.24 g·cm-2,respectively,and the minimum at 55.4% natural sunlight,being 44.89 cm2·g-1,52.84 cm·g-1,101.98 cm·g-1,0.04 g·cm-2,and 0.15 g·cm-2,respectively.The variation of the root/shoot ratio of Q.liaotungensis seedlings under different shading could be the effects of the combination of light intensity and water availability.