几种野生报春花的光合特性初探

 采用LI-6400便携式光合作用系统分析昆明室外栽培3年生的几种野生报春花光合作用特性.光补偿点(μmol·m^-2·s^-1)以被灯台报春最高(28),其余3种相近且较低(8～15).光饱和点以四季报春最低(80),其光合速率也最低,2种灯台报春的光饱和点(500)和光合速率均最高,灰岩报春居中.光合作用CO₂补偿点(μmol·mol^-1),灰岩报春54,桔红灯台报春64,粉被灯台报春69,四季报春80.光合速率和蒸腾速率日变化均呈单峰曲线,前者的峰值出现在10:00左右,后者的峰值出现在13:00左右;中午到下午光合速率降低的主要原因是气孔阻力增大,但17:00以后则主要是羧化阻力增大所造成.光合速率主要与叶片水分导性、蒸腾速率、光照强度和胞间CO₂浓度及气压相关.

Preliminary study of the photosynthetic characteristics in 4 wild Primula species

Plants of 4 wild Primula species were planted in the field in Kunming and the photosynthesis was tested with LI-6400 portable photosynthesis system.Species difference was found in light compensation point (LCP,μmol·m^-2·s^-1),light saturation point (LSP,μmol·m^-2·s^-1)and CO₂ compensation point (CCP,μmol·mol^-1) of photosynthesis. Primula pulverulenta Duthie had the highest LCP (28),the other 3 species had lower LCP(8-15).P.obconica Hance had both low LSP(80) and photosynthetic rate (Pn),and highest CCP(80).P.bulleyana Forr.and P.pulverulenta had both the highest LSP(500)and Pn,and intermediate CCP(64-69).P.forrestii Balf.f.had middle LSP and Pn,but the lowest CCP(54). The diurnal changes of Pn and transpiration rate (Tr) were one-peaked curves.Pn and Tr reached a maximum at about 10:00 and 13:00 respectively.Pn suppression at noon and in the afternoon was mainly caused by an increased stomata resistance,but this was the result of an increased carboxylation resistance at late afternoon. Pn was found closely correlated with leaf conductance to water,transpiration rate,photosynthetically active radiation, intercellular CO₂ concentration and atmospheric pressure.