RELATIONSHIP BETWEEN EVOLUTION OF CO2 AND GROWTH OF PLUM SHOOT TIPS CULTURED INVITRO UNDER DIFFERENT LIGHT-DARK REGIMES

The application of 4 h light followed by 2 h darkness (4/2 h), compare d to 16 h light - 8 8 h darkness (16/8 h), induced very different patt erns Of CO2 evolution from proliferating shoots of Prunus cerasifera i n vitro. Under the former light/dark regime, fresh and dry weights of shoot clusters and the number of newly formed shoots were increased. C ultures under 4/2 h showed a higher photosynthetic capacity at an earl ier stage of growth but this did not appear to be a factor in the enha nced growth. It is suggested that phytochrome may be involved in deter mining a different pattern of growth.