Isolation of chloroplasts in the Karwinskia species and determination of their photochemical activity under in vitro conditions

Reaction conditions for evaluation of the photochemical activity of isolated chloroplasts in the Hill reaction of Karwinskia humboldtiana (Roem & Schut) Zucc. and Karwinskia parvifolia Rose species were determined. Hill’s reaction activity was measured spectrophotometrically at 630 nm as the amount of DCPIP reduction by the chloroplast suspension at an irradiance of 400 µmol/m²/sPAR. A significant difference was observed between the activity of chloroplasts isolated at 2°C and 25°C amounting to 27% in Karwinskia humboldtiana and 18.5% in K. parvifolia. After 24 hours of storage of chloroplasts at a suspension of 2°C, a significant decrease of chloroplasts activity was noted in both species, e.g. 38% in Karwinskia humboldtiana and 45% in K. parvifolia. The photochemical activity of chloroplasts increased also with the length of irradiation of the reaction mixture and the content of chlorophyll (a + b) in chloroplast suspension. The activity of chloroplasts was found to be significantly higher in the species K. humboldtiana than in K. parvifolia and it proved higher in both when these were grown under field conditions rather than in a greenhouse.