不同光照条件对苹婆生长特性的影响

Effects of different light conditions on growth characteristics of Sterculia nobilis Smith seedlings

探讨不同光强下苹婆(Sterculia nobilis Smith)幼苗的生长特性及其对光照强度的适应特征,为苹婆幼苗合理栽培和抚育管理提供理论依据。采用遮荫处理模拟4种不同的生境光强:全光照(100%NS透光率)、一层遮荫(41.3%NS透光率)、二层遮荫(14.3%NS透光率)和三层遮萌(3.6%NS透光率),测定不同苹婆幼苗叶绿素含量、比叶重、叶面积、一级侧根数等生长生理指标。结果表明:叶绿素a、叶绿素b和总叶绿素含量随着光照强度降低呈上升趋势,叶绿素a/b值随着光照强度降低呈下降趋势;随着光照强度的减弱,苹婆幼苗的苗高增长量、地径增长量、平均单片叶干重、主根长度、一级侧根数、地上部分鲜重、地下部分鲜重、整株鲜重、地上部分干重、地下部分干重、整株干重、根冠比均呈先升高再下降的变化趋势,且都在41.3%NS下达到最大;而叶柄长呈不断上升的变化趋势,并在3.6%NS达到最大;平均单片叶面积呈现先上升再下降的变化趋势,在14.6%NS下达到最大值;比叶重则呈不断下降的变化趋势,在100%NS光照下值最大。表明全光照和3.6%透光率条件会抑制苹婆幼苗的生长,50%左右的对幼苗更适宜。

The effects of different light intensities on the growth characteristics of Sterculia nobilis Smith seedlings were studied to offer a theoretical basis for its cultivation and management. Different light environments were simulated with four different shading treatments, FL： 100%NS （ natural sunshine ） ; L1 ： 41.3%NS; L2： 14.3%NS; L3： 3.6% NS. The chloroplast pigments content, specific leaf weight, leaf area, primary lateral root number were measured. The results showed that the contents of chlorophyll a, chlorophyll b and total chlorophyll showed a trend of increased with light intensity decreasing, the value of chlorophyll a/b decreased. With the decrease of light intensity, the seedling height growth, diameter growth, average single leaf weight, taproot length, primary lateral root number, upper ground flesh weight, root fresh weight, total flesh weight, upper ground dry weight, root dry weight, total dry weight, mot cap ratio of S. nobilis Smith seedlings all showed downward trend after the first rise, and reached the maximum in 41.3%NS; while the petiole length presented a increasing trend, and reached the maximum in 3.6%NS; the average single leaf area first increased and then decreased, and reached the maximum in 14.6%NS; the specific leaf weight showed a decreasing trend and reached the maximum in 3.6%NS. Results indicated that the photosynthetic mechanism of S. nobilis Smith seedlings was destroyed under full hght and 3.6% full light, and about 51Y7o full hght condition was most suitahle.