The relation between flower initiation and sink strength of stems and tubers of Jerusalem artichoke.

Abstract

In a field experiment with a late cultivar (Violet de Rennes) the relation between flower initiation and the onset of redistribution of stem reserves and rapid tuber filling was studied. The treatments, which comprised long day (18-h photoperiod) treatment, application of the growth retardant triapenthenol at 3 kg/ha, transplanting or delayed planting, were designed to vary the duration of the vegetative plant stage or to alter the pattern of dry matter distribution. During the vegetative stage, tuber growth proceeded at a slow rate (about 20 kg ha^-1 d^-1) and inulin accumulated in the stems. With the plants that were kept vegetative by prolonging daylength, the tuber growth rate remained at that low level until final harvest. At the beginning of Sep. the plants in all other treatments showed flower initiation at the apices and thereafter tuber filling rates were much higher. From the similar growth rate per tuber, with crops differing considerably in tuber number per unit area, it is concluded that total tuber growth depends not on assimilate availability but on the storage capacity, i.e. the number of tubers or number of storage cells, and is therefore sink limited. Tuber number appeared to be linearly related to a cumulative temperature. The changes in relative sink strength of stems and tubers over the growth period are discussed as well as the metabolic costs and economic risks of the temporary inulin storage in the stems. (Abstract retrieved from CAB Abstracts by CABI’s permission)