遮荫处理对泡泡树幼苗生长的影响

目的]为了研究遮荫对泡泡树幼苗生长的影响,为其苗木生产提供理论依据。方法]于2005年选择干茎粗、株高基本一致且长势良好的70 d苗龄的泡泡树为材料,设全光照(100%光强)1、层、2层和3层黑色遮光网(透光率分别为为50%、25%和12.5%)4个光照梯度处理,研究了不同遮荫处理对其生长的影响。结果]1层网和2层网遮荫处理的泡泡树幼苗植株生长较快;随着光照强度的减弱,泡泡树叶片中叶绿素a、叶绿素b以及叶绿素总量先增加后逐渐降低,叶绿素a/b的值随之变小;全光照处理下,幼苗消耗较多水分,在下午15:00时土壤温度显著较高;遮荫处理组间差异较小。结论]50%透光率的遮荫有助于泡泡树幼苗生长,株高及干径增长快。在透光率为50%的遮荫条件下,泡泡树叶片的叶绿素a含量及叶绿素总量最高,幼苗生长较为适宜。

Effects of Shading Treatments on Growth of Asimina triloba (L) Dunal Seedlings

Objective] The study was conducted to investigate the effects of shading treatments on growth of Asimina triloba(L) Dunal seedlings and lay the theoretical basis for seedling production.Method] In the test in 2005,with 70 day-old A.triloba seedlings which had consistent stem diameter and plant height and good growth vigour as tested materials,4 light gradient treatments of the natural light with 100% light intensity,one-layer,two-layer and three-layerr black shading network with the light transmittance rate being 50%,25% and 12.5% were set up to study the effects of different shading treatments on growth of A.triloba.Result] Under the shading treatments of one-layer and two-layer network,the plants of A.triloba seedlings rapidly.As the intensity of illumination decreased,the contents of chlorophyll a(Chl.a),chlorophyll b(Chl.b) and total chlorophyll all were first increased and then reduced,and the chlorophyll a/b value became smaller.Under natural light the plants tended to consume more water and the soil temperature at 15:00 p.m was higher.There was a smaller difference among various treatments.Conclusion] The suitable shading favored to the growth of A.triloba seedlings and increased the tree height and stem diameter.Under the light transmittance rate of 50%,the Chl.a content and total chlorophyll in the leaves of A.triloba seedlings were highest and it was proper to the growth of A.triloba seedlings.