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.“Zhongjiao No.5”,“Zhongjiao No.6”，“Zhongjiao No.10”and“Hongyingda”,under 300μmol/m²·s and 100μmol/m²·s artificial light were studied.The results show that under weak light,net photosynthetic rate (P_n),dark respiration rate (R_d),night respiration rate (R_n),saturation light (SL),light compensation point (LCP) decrease,but apparent quantum yield (AQY) increases.The decrease of P_n under weak light is the result of non-stomatal limitation.The important cause of P_max 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.10”with relatively lower LCP,R_d and R_n,higher AQY under weak-light shows a potential weak-light-tolerance.