Photosynthetic characteristics of chloroplasts of primary wheat leavesgrown under different irradiance

摘要

The rate of accumulation of total chlorophyll (Chl) and carotenoids (Car) of leaves grown under high irradiance, HI (30 and 45 W m(-2)) was faster than at moderate irradiance, MI (15 W m-2). However, the senescence phase started earlier in the samples and proceeded at a faster rate. Chl alb and Chl (a+b)/Car values showed faster loss of Chl a (compared to Chl b) and Chl (a+b) (compared to Car) in III leaves. Protein accumulation and loss were also similar to that of Chl (a+b) content. Increase in Chl fluorescence during the development phase may suggest a gradual change in thylakoid organisation, however, the temporal kinetics were different in HI and MI samples. Increase in fluorescence polarisation during senescence of HI leaves compared to the control (MI) suggests conversion of thylakoid membranes to get phase. Chloroplasts prepared from HI seedlings showed higher rate of photochemical activities, however, the activity declined earlier and at faster rate compared to the control.