摘要
我们研究的十个种类杨树的光合作用存在着显著差异,净光合速率在10.97—17.62mgCO_2·dm^(-2)·h^(-1)之间;光呼吸速率在2.28—5.86mgCO_2·dm^(-2)·h^(-1)之间;光饱和点在20000—40000Lux的范围内。作者认为“净光合速率×总叶面积”的积可以用来作为确定杨树生长潜势的可靠指标。测定了3种杨树光合速率的垂直分布,表明未展开的幼叶CO_2同化量是负值,光合速率最高值出现在完全展开叶的第4—6片,然后逐渐下降。最速生的72—170苗木的光合速率从第6片叶开始下降得比其亲本引河1~#和北京杨0018要缓慢得多。这种光合速率的垂直分布可作为选育杨树无性系的有价值的指标。本文还利用光饱和点、CO_2补偿点、Hill反应等指标对选择优良无性系进行了探讨。
The different kinds of poplar tree were shown to quite distinct in their photosynthtcic ability: rate of net photosynthesis 10.97-17.62 mg CO2·dm-2·h-1; rate of photorespiration 2.28-5.86 mg CO2·dm-2·h-1; light saturation point 20000-40000 Lux The author suggests that net photosynthctic rate multiplies by total-area is a reliable value to show the potentiality of the seedling.By comparing the vertical distribution of photosynthetic rates as determined from three polar species,it can be shown that the CO2 assimilating value of the unspreading young leaves was negative.The maximum photosynthetic rate occurred in the 4th--6th fully spread leaves and gradually decreased in the leaves below them.Decreased of the pho- tosynthetic rate of the most fast growing variety 72-170,began from the 6th leaves and below,was much slower their pa-rent plant,i.e.variety Yin-ho No.1 and Popular pekiensis 0018.This kind of vertical distribution of photosynthetic rate can be used as a valuable index of fast growing clones in poplar breeding.To use light saturation point,CO2 compensation point and Hill reaction as indices for breeding best clones was also discussed.
