PRODUCTION OF POTATO MINITUBERS BY REPEATED HARVESTING - PLANT PRODUCTIVITY AND INITIATION, GROWTH AND RESORPTION OF TUBERS

Plant growth and tuber initiation, growth and resorption were studied in two potato cultivars, grown for minituber production under tuber inducing conditions. Plants were harvested up to three times within 11 weeks, using one or two non-destructive harvests at which minitubers (greater-than-or-equal-to 0.3 g) were removed and plants were replanted. The first non-destructive harvest stimulated the initiation of new tubers. A part of these tubers grew to a size of greater-than-or-equal-to 0.3 g within three weeks. The other tubers remained < 0.3 g and many of them were resorbed during plant senescence. A second non-destructive harvest, three to four weeks after the first harvest, stimulated initiation of new tubers only in young plants of one cultivar, but always stimulated growth of tubers that otherwise would have been resorbed or would have remained < 0.3 g. Again, a part of the tubers grew to a size of greater-than-or-equal-to 0.3 g within three weeks. Thus, the number of minitubers increased after both non-destructive harvests. Tuber and overall growth rates, however, were reduced. A production scheme for practical minituber production is suggested, consisting of 3 harvests and yielding over 1800 minitubers per m2, all greater-than-or-equal-to 0.3 g and weighing on average 1 - 2 g.