MICROTUBER AND MINITUBER PRODUCTION AND FIELD PERFORMANCE COMPARED WITH NORMAL TUBERS

Microtuber and minitubers of cv. Monalisa were produced in the laborat ory and compared with normal seed tubers in a held experiment. These t ubers were planted at similar plant densities (13.6 sprouts per m(2)) with two distances between rows (60 and 90 cm). Final ground cover was almost complete only in the plots derived from normal tubers and decr eased with the size of the mother tubers. Normal seed, mini- and micro tubers yielded respectively 50.8, 31.7, and 17.0 t/ha (means of two sp acings). At close and wide spacing between rows, microtubers yielded r espectively 27.3 and 6.7 t/ha, and minitubers 38.9 to 24.3 t/ha. Row s pacing did not influence the yields from normal seed tubers. Total num ber of tubers per m(2)?- was also affected and, as means of the two sp acings, ranged from 107.8 with microtubers, 122.1 with minitubers, to 142.9 with normal tubers. Mother tuber type also affected the yield di stribution in three tuber grades (<36, 36-55, and 55-80 mm) and micro and minitubers produced many small tubers. Multiplication rates and th e possible use of different propagation sources are discussed.