光照强度对伯乐树幼苗生长及相关生理指标的影响

以浙江江山种源的伯乐树容器苗为研究材料，在苗木的整个生长季设置4种不同强度的自然光照处理，分析不同光照条件下伯乐树幼苗的生长与形态指标、叶绿素含量与光合特性参数等生理指标，探讨伯乐树幼苗生长适宜的光照条件。结果表明：在幼苗生长期中，3种低光照强度处理的苗木高径增长量、生物量均高于100%光照处理，其中，30%光照处理的高径增长量分别为100%光照处理的1.65、1.44倍，总生物量为100%光照处理的2.67倍，两者间差异达显著性水平；幼苗叶片厚度持续增加，在试验后期各处理间无显著差异；比叶质量始终以30%光照处理最低，100%光照处理始终高于其他3个处理。8—10月叶绿素含量发生明显的变化，由低光照处理显著高于100%光照处理转变为100%光照处理显著高于低光照处理。100%光照处理下蒸腾速率最高，但其水分利用效率较低；而30%光照处理水分利用效率最高，长势最好。因此，伯乐树幼苗生长不耐强光，幼苗夏季需进行适当的遮光处理，以30%光照强度为最佳。

Effects of Light Intensity on the Growth and Related Physiological Indexes of Bretschneidera sinensis

Container seedlings of Bretschneidera sinensis from Jiangshan, Zhejiang with 4 different natural sunlight treatments in open field during the whole growing season were used to compare and analyze growth and morphological indexes, chlorophyll content, photosynthetic characteristics and other physiological indexes of seedlings explore the suitable light conditions for the growth of B. sinensis seedlings. The results showed that the increases in height and caliper, biomass of seedlings under the three low-light intensity treatments were all higher than 100% light intensity treatment, increasse in height and caliper of 30% light intensity treatment was 1.65 and 1.44 times of 100% light intensity treatment, and the biomass of seedlings was 2.67 times of 100% light intensity treatment. The thickness of the leaves of different treatments continued to increase, but at the end of the test there was no significant difference. The specific leaf weight of 30% light intensity treatment was the lowest, while that of 100% light intensity treatment was significantly higher than that of other 3 treatments throughout the test period. From August to October, the chlorophyll content changed from shading treatment significantly higher than 100% lighting to 100% lighting significantly higher than shading treatment. The transpiration rate (Tr) of the 100% light intensity treatment was highest, but the water use efficiency (WUE) was lowest. However, WUE and the growth of 30% light intensity treatment were all the best. Therefore, B. sinensis seedlings were not resistant to strong light, should to be properly shaded in summer with 30% light intensity as the best.