不同光强对吴茱萸生长动态和光合日变化的影响

报道了不同生长光强(透光率分别为15%、30%、50%、100%)对吴茱萸的生长和光合日变化的影响。结果表明:生长环境光强对吴茱萸苗期株高、地径和冠面积的影响较大,100%RI下的株高、地径和冠面积明显小于各遮荫处理,其中30%RI下吴茱萸的株高、地径和冠面积最大,这表明苗期强光不利于吴茱萸的生长。随着光强的减弱,吴茱萸增大冠面积与株高有利于截获更多光能。10月下旬,100%RI下吴茱萸净光合速率(Pn)日变化曲线呈"双峰型",11:30～14:30,吴茱萸的Pn、胞间二氧化碳浓度与气孔导度均下降,表明此时的光合午休现象是由气孔部分关闭造成的。各遮荫处理下,吴茱萸的Pn日变化均呈"单峰型",并无第二峰的出现,可能与遮荫条件下,下午光强较弱,环境温度较高,空气相对湿度较低有关。

Effects of light intensityon the growth and diurnal variation of photosynthesis in Evod iarutaecarpa seedlings

The growth and diurnal variation of photosynthesis to different shading levels(15%,30%,50%,100%relative inadianes) in Evod iarutaecarpaseedlings were examined.The results showed that,the height,diameter and crown area of E.iarutaecarpaseedlings were significantly influenced by growth light intensities.The three properties under 100%sunlight were significantly lower than which under other sunlight,and those properties under 30% sunlight were the largest.It could be seen that high light was not conducive to the growth of Evod iarutaecarpaseedlings.With the decrease of light intensity,the crown area and height of E.iarutaecarpaincreased significantly,which enhanced the light interception in low light.In late October,diurnal variation in net photosynthetic rate(Pn) was two-peak pattern in E.iarutaecarpaunder 100% sunlight.From 11:30to 14:30,the Pn,intercellular CO 2 concerntration and stomatal conductance were all decreased,which indicated that stomatal partial closure was the main direct factors which affected the diurnal variation of Pn.The Pndid not show second peak during the afernoon in E.iarutaecarpaseedlings under three shading treatment,which was related to the low light intensities,high air temperature and low air relative humidity in the afernoon under shading treatment.