EFFET DES DATES DE PLANTATION SUR LES POMMES DE TERRE CULTIVEES EN SAISONS COURTES
The effect of planting dates on growth and quality of potato tubers (Solanum tuberosum L.) grown on a wet and cold soil was studied. Ninety days after planting, total yield was higher in plots planted in mid-June than in those planted at the end of May. However, 110 days after planting, yield was higher with the earlier planting dates. Yield at 130 day s after planting was not significantly different from yield at 110 days after planting. Tuber growth ended on 15 Sept. in 1975 and on 30 Sept. in 1974 and 1976. Percentage of tubers 70 mm and more in size was four times higher at 110 than at 90 days after planting for cv. Kennebec at the first planting date. Increase in tuber size was lower for cvs. Norland and Netted Gem and for all other planting dates. In spite of a low increase of specific gravity, chipping quality decreased as harvest was delayed. Percentage of tubers bearing Rhizoctonia sclerote increased as harvesting was delayed.