Changes in photosynthesis in potato during tuberising and non-tuberising phases

Photosynthesis and chlorophyll fluorescence induction kinetics were measured in potato plants exposed to tuber inducing and then to non-inducing conditions. One day after the shift, there was 34% reduction in the rate of photosynthesis, 33% increase in half quenching time of variable fluorescence and 8% reduction in quantum yield. Although half quenching time and quantum yield recovered to the original values under tuber inducing conditions, the rate of photosynthesis never recovered fully and remained at the level of young plants before tuber initiation. The study indicated that tubers act as major sinks for photosynthates and directly influence the rate of photosynthesis.