Response of photosynthesis and respiration to weak light in seedlings of four capsicum cultivars

The characters of photosynthesis and respiration in seedlings of four capsicum cultivars,i.e. No.5, No. 6, Zhongjiao No. 10andHongyingda, under 300μmol/m2·s and 100μmol/m2·s artificial light were studied. The results show that under weak light,net photosynthetic rate (Pn) ,dark respiration rate (Rd),night respiration rate (Rn),saturation light (SL),light compensation point (LCP) decrease,but apparent quantum yield (AQY) increases. The decrease of Pn under weak light is the result of non-stomatal limitation. The important cause of Pmax decreasing is lower rubisco carboxylation activity. Under weak light the chlorophyll content(Chl.)increases, but the chlorophyll a/b ratio (Chl. a/b) and specific leaf mass (SLM) decline. Among four capsicum cultivars,Zhongjiao No. 10with relatively lower LCP,Rd and Rn,higher AQY under weak-light shows a potential weak-light-tolerance.