Abstract: | The basis of differences in tuber yield of potato cv. Kennebec, due to varying stem numbers per plant, was studied by measuring changes in leaf-area and dry weight throughout the season. Initially the dry weight yield of tubers was related to leaf-area but following the attainment of maximum leaf-area this relationship no longer held. The final yield of tubers was shown to depend mainly on the net assimilation rate (E) late in the season. At this time E was controlled by the sink demands of the bulking tubers and these in turn were influenced by tuber number. Yields increased as the number of stems increased through one, two and four per plant-hill. |