اثرات تيو اوره و اسيد جيبرليك بر شكستن دوره ي خواب ميني تيوبر سيب زميني در رقم آگريا

Effects of Thio-Urea and Gibberellic Acid on Dormancy Breaking of Potato Mini-tubers in Agria cultivar

To evaluate the effects of Thio-Urea and Gibberellic acid on mini-tubers of Agria cultivar a factorial experiment based on randomized complete block design with three replications was conducted. Tretments were five levels of mini-tuber weight groups (<0.5, 0.5-0.99, 1-1.99, 2-2.99 and > 3 gr.) and five levels of chemical compounds (two levels of gibberlic acid concentration of 1000 and 1500 ppm, two levels of Thio-Urea with 3% and 5% and a control). Some attributes such as days to sprouting, number of rotten mini-tubers and number of sprouts per mini-tuber were measured. After breaking dormancy, mini-tubers were planted in a greenhouse and traits such as stem number and plant height were also measured during growth period. Tubers were harvested after 90 days of growth and then tuber diameter and weight of mini tubers per plant were recorded. Results showed that 1500 ppm GA3 was suitable to break dormancy of mini-tubers smaller than 1 gr and 5% Thio-Urea was suitable for breaking dormancy of mini-tubers bigger than 1 gr. Mini-tubers smaller than 0.5 gr. had the longest sprout and the most sprout number per mini-tuber. Using chemical compounds to break dormancy reduced tuber yield by 920-2330 kg/ha and tuber weight by 12.9-27.7 gr. per plant. Reduction rate of tuber yield per hectare and tuber weight per plant after breaking dormancy through Thio-Urea 5% application was lower than other treatments. This in dicates that you can save cost of mini-tubers production. Mini-tubers smaller than 1 gr. produced maximum yield and its components.