Breaking Physiological Dormancy in Tubers of Solanum Chacoense.

Solanum chacoense is a wild specie relative of the common potato (S. tuberosum) native to South America, which has become source of genetic material for breeding for superior root biomass and higher N use efficiency. Little research has been conducted on S. chacoense for breaking physiological dormancy in tubers. Inability to readily break dormancy in S. chacoense tubers may result in uneven emergence contributing to experimental error. The objective of this study was to determine an appropriate concentration and soak time combination of GA3 to encourage sprout formation alongside minimizing elongation. Tubers were treated with four concentrations of GA3 (0, 50, 100, and 150 µg/ml) over three soak periods (5, 45, and 90 min). Tubers were kept in environmental controlled incubator at 25 ºC under fluorescent lights for 24 h/day during 46 days. Significant interactions between genotypes and treatment (p< 0.001) were observed for sprout length at 46 DAT and sprout number between 9 and19 DAT. Under the 0 µg/ml GA3 concentration, the first sprout number was observed between 12 and 46 DAT. First sprout occurred between 9-46, 16-43, 9-46 for the rates of 50, 100 and 150 µg/ml, respectively. At 9 DAT, Genotypes A-3 and B-3 showed the greatest sprout number (µ=0.33; µ=0.44) in response to the 50 µg/ml/45 min soak. At 19 DAT, the GA3 concentration of 150 µg/ml applied at 5 and 90 min soaking times resulted in the highest number of sprouts in A-3 (µ= 2.20; µ= 1.80). Genotype A-3 under 50 µg/ml/5 min soak and B-3 under 0 µg/ml/5 minute soak exhibited the longest and shortest average sprout lengths (µ= 18 and µ= 0.8 mm), respectively. Genotypes D-6, D-7, D-8 did not respond to any of the GA3 treatments.