滨海围垦地2种木本植物光合特性的研究

Studies on photosynthetic characteristics of 2 species of woody plants in coastal reclamation land

采用Li-6400便携式光合仪,对上海南汇区围垦地乌桕、女贞光合特性进行了测定。结果表明,女贞、乌桕的光饱和点分别为1 583.200,920.760μmol.m-.2s-1,它们均为喜阳树种;乌桕和女贞的日变化曲线均为双峰曲线,出现光合"午休"现象,引起乌桕"午休"的原因为非气孔因素,引起女贞"午休"的原因为气孔因素;水分利用效率日均值为乌桕(2.512)大于女贞(1.591)。乌桕在夏季生长期,保持高的水分利用效率,积累较多的有机物质,生长适应性优于女贞。环境因子中,光照和大气相对湿度是影响2种植物光合作用的重要因子。

By means of Li-6400 portable photosynthetic system,the diurnal-variation of photosynthetic characteristics of Sapium sebiferum and Ligustrum lucidum was investigated at coastal reclamation land in Nanhui District,Shanghai.The results showed that：（1）the light saturation point of 2 kinds of plants were 1 583.200,920.760 μmol · m-2 · s-1 respectively,thus they could be viewed as heliphytes;（2）the diurnal courses of the photosynthetic rates of S.sebiferum,L.lucidum were doubled-peaked,and midday photosynthetic depressions occurred in both species.The reasons of midday depression phenomenon of photosynthesis were,however,different,e.g.stomatal limitation for L.lucidum and non-stomatal limitation for S.sebiferum;（3）daily average WUE（water use efficiency） was higher in S.sebiferum（2.512） than in L.lucidum（1.591）.Thus the accumulation of organic matter was higher in S.sebiferum than in L.lucidum.The former grew better than the latter.Pn（net photosynthetic rate） was mainly affected by PAR（photosynthetically active radiation） and RH（relative humidity） among the environmental factors.