豫西刺槐能源林培育的光合生理生态理论基础

A preliminary study on the photosynthetic characteristics of varied cultivars of Robinia pseudoacacia L. energy forest in the west of Henan Province

采用LI-6400便携式光合作用测量系统对豫西丘陵区当年生5个品种的刺槐叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)等光合生理参数及光响应过程进行了测定,结果表明:(1)5个刺槐能源林品种在7月中旬、8月中旬及9月底的净光合速率日变化峰值大都分别出现在12:00、08:00或10:00、10:00。(2)不同刺槐品种生长节律间具有明显的差异,品种83002、8048、8044在7月份处于生长盛期,而品种3-I在9月份进入生长盛期;84023、3-I及83002具有相对良好的光合物质积累能力,具有刺槐能源林高产品种的光合特征。(3)供试刺槐品种在7月中旬更多地表现为非气孔限制为主导因素的光合限制,而在8月中旬及9月底则均表现为气孔限制和非气孔限制两种因素交替主导。(4)5个供试品种所测得的光饱和点均在1000μmol.m-.2s-1以上,供试品种在7月中旬均不会出现强光抑制情况,品种83002出现午休现象的原因可能是温度上升与湿度下降综合作用的结果。

Photosynthesis is the basis of other physiological activities including growth,development,and food formation in trees.In order to discuss the photosynthetic theoretical basis for the cultivation of Robinia pseudoacacia L.energy forest,the photosynthetic parameters,i.e.Pn,Tr,Gs,etc,as well as photosynthetic light-response curves of 5 varieties of Robinia pseudoacacia were measured using the Li-6400 portable photosynthesis system in the west of Henan Province,China.Four main conclusions were gotten.The peak value of net photosynthetic rate（Pn） of 5 varieties of Robinia pseudoacacia occurred at noon,08： 00 or 10： 00 a.m.,10： 00 a.m.in mid-July,mid-August and late September respectively.Obvious difference existed among growth dynamics of 5 varieties,and varieties 83002,8048 and 8044 showed fast growth rate in July,while variety 3-I grew fastly in September.Varieties 84023,3-I and 83002 were found having relatively high photosynthetic accumulation capacity and had the high-yield photosynthetic characteristics.Based on the tendency of changes in Pn,intercellular CO2 concentration（Ci）,stomatal conductance（Gs） and stomatal limitation（Ls）,we speculated that Robinia pseudoacacia were restricted in photosynthetic ability mainly by non-stomatal factors in mid-July,while they were restricted mainly by both stomatal factors and non-stomata factors in mid-August and the end of September.Light is the power in photosynthesis.Light compensation point is a critical value,over this value plant still can maintain photosynthesis.Light saturation point is a limit value,over this value photosynthetic rate does not increase,even decrease.Light saturation point（LSP） of Robinia pseudoacacia varieties were all greater than 1000μmol·m^-2·s^-1,and so,these tested varieties all could not suffer restriction from strong light occurred in mid-July.Photosynthesis is related to temperature,light radiation and CO2 concentration,which are necessary to valuate photosynthetic capacity.Except variety 83002,net photosynthetic rate（Pn） of other four varieties of Robinia pseudoacacia had only one peak,only variety 83002 had two peaks,one at 10： 00 a.m.and the other at 02： 00 p.m.Transpiration rate（Tr） of varieties 83002 and 84023 had two peaks,the others had one peak only.The phenomenon of＂photosynthesis sleep at noon＂of variety 83002 might be explained as the combined result of both increment in temperature and drop of relative humidity.It was suggested that in order to estimate photosynthetic accumulation capacity and select one quality variety,the photosynthetic characteristics of varied cultivars of Robinia pseudoacacia L.energy forest could be analyzed.