红锥苗期生长特性和叶绿素荧光对不同光强的响应

Effects of different light intensity on characteristics of growth and chlorophyll fluorescence of Castanopsis hystrix seedlings

研究了不同光强下(全光照、遮荫下光强分别相当于自然光照的80%、30%和20%)红锥盆栽幼苗的生长特性及叶绿素荧光参数的动态变化。结果表明,遮荫条件下红锥幼苗较全光照下生长迅速,苗高在30%光强下生长最好,地径在80%光强下生长最好。遮荫条件下的红锥幼苗叶绿素a、b和总叶绿素含量均上升,且与全光照条件下差异显著,30%光强下含量最高。类胡萝卜素含量随光强降低,稍微下降后呈上升趋势,80%光强下的值最低,与全光照差异不显著,20%光强下最高,与其差异显著。遮荫条件下的φ(PSⅡ)、F o、F m、F v/F m和F v/F o值均高于全光照条件下,且低光强下(30%和20%光强)的φ(PSⅡ)、F o、F m、F v/F m和F v/F o值维持在一个较高的水平。这些现象表明,南宁地区的强光环境对红锥幼苗的生长及光合作用有一定的负效应,进行适当遮荫或者让其在林下生长是有利的。另红锥幼苗叶绿素荧光参数随月份的推移表现出了明显的季节变化。

The growth characteristics and the dynamic changes of chlorophyll fluorescence parameters of Castanopsis hystrix potted seedlings exposed in four illumination intensity （full-exposure, shaded to 80%, 30% and 20% of ambient light） were investigated. The results show that seedlings under shaded condition grew more rapidly than those fully exposed, the seedlings with 30% ambient light had the highest height growth values and the ground-diameter growth was the fastest with 80% ambient light; The chlorophyll contents （chlorophyll a, chlorophyll b and total chlorophyll） increased under shaded conditions more than that of full exposure （P〈0.05）, showed the highest content under 30% ambient light; The carotenoids reduced with the initial increase of light intensity, then presented a rising trend, and reached the lowest under 80% ambient light （P〉0.05, compared with full exposure）, went up to the highest under 20% ambient light （P〈0.05）; The chlorophyll fluorescence parameters φ（PS Ⅱ）, Fo, Fm, Fv/Fm and Fv/Fo under the shaded condition of were higher than those under full exposure, and they all maintained at high level under low light intensity （20%, 30% ambient light）; The findings suggest that the intense sunshine is somewhat negative effect to the growth and photosynthesis of hystrix seedlings in Nanning, therefore shading or growing under forest will be beneficial for the seedling＇s development. In addition, the chlorophyll fluorescence parameters showed a significant seasonal variation.