Different pre-sprouting methods for early tuber harvest in potato (Solanum tuberosum L.)

Earlier harvest of potatoes (Solanum tuberosum L.) can be achieved by different treatments of the seed tubers. This can be important, for example, in areas with a short growing season and in organic farming. In a pot experiment, different pre-sprouting methods were evaluated for four cultivars. The experiment consisted of (a) untreated seed tubers stored at 4 °C until planting, (b) traditional pre-sprouted tubers (P) and (c) pre-sprouted tubers with stimulation of adventitious root formation (PR). Pre-sprouted seed tubers have earlier and faster tuber formation, but often lower yield than non pre-sprouted tubers if there is no restriction of the growing season. The PR method developed here, where tubers were sprayed with water to stimulate adventitious root formation and give faster development and tuber initiation than conventional pre-sprouting, can be of value when the growing season is restricted or if early harvest is important. Initial emergence of the pre-sprouted potatoes was monitored in two pot experiments. Emergence was faster for the pre-sprouted treatments compared with the control, but there were no significant differences between the two pre-sprouting methods. At harvest, the pre-sprouted treatments gave higher yield than the control for all growing periods, methods and cultivars, although the differences were not significant for every combination. The cultivars Matilda, Cicero, Ovatio and Superb seemed to respond more positively in terms of yield to PR treatments than cv. Ditta. The new method for stimulating adventitious root formation developed here will substantially help growers to achieve earlier harvests.