Dormancy response of potatoes to gibberellic acid and thiourea
1991
Al-Fayyad, M. | Kasrawi, M.A. (Jordan Univ., Amman (Jordan))
Laboratory and field experiments were conducted to study the effects of gibberellic acid and thiourea on the tuber dormancy period of five potato cultivars. In the laboratory experiment, 17 treatments of various concentrations of GA3 and thiourea with variable dipping times were applied one or two times to freshly harvested tubers. Significant differences were found among cultivars, treatments and cultivar x treatment interaction. Cultivar Diamont sprouted earlier and had a higher number of and longer sprouts per tuber than Spunta which sprouted latest. GA3 at 5ppm only or in combination with 1% thiourea was more efficient in reducing the number of days to tuber sprouting and increasing the number of sprouts per tuber and sprout length. Dipping tubers for 5 min. in 5 ppm gave earlier sprouting, a higher number of sprouts per tuber, and longer sprouts as compared to dipping for 60 min. in the same solution. Increasing the number of applications from 1 to 2 had no significant effect on the number of days to sprouting and the sprout number per tuber. In the field experiment, 8 treatments of different concentrations of GA3 and thiourea were applied for 5 min. (dipping time) to freshly harvested tubers of the same cultivars used in the lab experiment. Dormant tubers treated with 5 or 10 ppm GA3 or in combination with 1% thiourea were the best in enhancing shoot emergence of dormant tubers and in reducing the length of the dormancy period by about 2-3 weeks as compared to the untreated control
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