Sink strength and photosynthetic capacity influence tuber development in sweet potato

Summary

Tuber growth of sweet potato clones is shown to depend on the sink strength of the developing tuber, the potential of leaves to export photoassimilates, but also on the photosynthetic capacity of leaves. Evidence from experiments with the short-lived radioisotope ¹¹C and from growth experiments in the glasshouse is presented in favour of the hypothesis that tuber formation promoted photoassimilate export from fully expanded leaves and also leaf photosynthesis. In the sweet potato clone ‘AB94078.1’, a low photosynthetic capacity could be explained by a limitation of Calvin cycle activity, notably of Rubisco activity. The light reactions of photosynthesis did not limit net photosynthesis in the investigated clones under the non-saturating light conditions during the experiment.