GÁS DISSULFETO DE CARBONO NA QUEBRA DE DORMÊNCIA DA BATATA-SEMENTE

The objective of this research was to evaluate the efficiency of the carbon dissulfate gas in different doses and time of application in breaking the dormancy of tubercles of 3 cultivars of potato-seed, after 30 days of harvesting. The experiment was conducted in the Seed Laboratory of the Department of Fitotecnia and Fitossanitarismo of the Section of Agrarian Sciences of UFPR. Was used tubercle of potato-seed of the type II (between 41 and 50 mm diameter). The research work was divided in two stages: 1st - October of 2003 with the cultivars: Asterix and Cupido from Guarapuava - PR; and 2nd - February of 2004 with the cultivars: Asterix and Monalisa from Canoinhas-SC. The treatments were exposing the potato-seeds with the carbon dissulfate gas in the doses: 1,04, 1,38, 1,73, 2,07 and 2,42 ml.m-3 during the periods of 60, 72 and 84 hours. The tubercle were conditioned in carton boxes (69,120 cm 3 ). Each carton box with 20 tubercle. The carbon dissulfate gas was placed in a plastic tray (250 ml). Soon after the carton boxes were sealed with adhesive tape and placed inside of a plastic bag polyethylene to avoid the evaporation of the gas. The potato-seeds were maintained in the temperature of 22° C up to 25° C under indirect light, during the 30 days of evaluation. The data were weekly performed totalizing three readings of the number of sprouts by tubercle and the determination of the length of each sprout. The experimental design was a completely randomized design, in a factorial experiment (3x5) with four (4) replications. The mean separation was determined by DMS (99%). The results of the experiment 01, for the cultivars Asterix and Cupido, suggest that the use of the carbon dissulfate gas is effective for breaking the dormancy, promoting larger number and length of sprouts when the tubercles were exposed to the gas in the time of 72 hours in the dose of 1,73 ml. cm-3. The experiment 02, for cultivars Asterix and Monalisa, the results suggest the use of the carbon dissulfate gas in the time of exhibition of 72 hours. The doses for this experiment were not significant.