Effect of dormancy breaking chemicals on microtuber production potential under in vivo conditions of central India

The present study was carried out at ICAR -Central Potato Research Station, Gwalior during 2012-13 to assess the effect of dormancy breaking chemicals, their dip duration and microtuber size on growth and yield parameters. The three different size >4-6mm, >6-8mm and >8mm of variety Kufri Sindhuri were given dip treatment with six types of growth regulators/ dormancy breaking chemicals viz 1ppm gibberelic acid, 0.5 ppm gibberllic acid, 1% thiourea, 0.5 % thiourea, 1ppm gibberllic acid + 1% thiourea and 0.5 ppm gibberllic acid + 0.5 % thiourea along with water control for 30 min, 45 min and 60 min. All the treatments exhibited better growth and yield parameters over water control but significantly best at 5% was 0.5 ppm gibberllic acid treatment for growth parameters and 0.5 ppm gibberllic acid + 0.5 % thiourea treatment for yield parameters. All the dip duration 30 min, 45 min and 60 min had not significant at 5% level effect for both growth and yield parameters. The larger sized micro-tuber (>8 mm) showed significantly superior plant emergence, plant height, number of compound leaves per plant, number of stems per plant both at 50 and 75 days after planting followed by 4-8 mm grade and <4 mm grade micro-tubers. Similar trend was observed for all the yield parameters. The overall mean finding indicates that micro-tubers treated with 0.5 ppm gibberllic acid in combination with 0.5 % thiourea gave highest yield (226.0 q/ha tuber), among micro-tuber size of >8mm (295.0 q/ha tuber) and among dip duration 30 min (206.67q/ha) and 45 min (210 q/ha) resulted in significantly higher yield parameters under nucleus seed production in in vivo conditions of central India.

Effect of ethanol and plant growth regulators on termination of potato microtuber dormancy

The duration of dormancy varies significantly among cultivars, but even short dormancy can limit usage of potato microtubers for seed production. The aim of the research was to test efficacy of dormancy breaking by treatment with an aqueous solution of ethyl alcohol, saccharose, gibberellic acid and kinetin (ethanol treatment) in comparison to treatment with aqueous solution of thiourea, daminozide and gibberellic acid (standard treatment). Prolonging the period of microtuber production at the in vitro stage significantly favored the short-ening of the dormancy and facilitated its breaking. While the standard treatment had the strongest effect, the ethanol treatment was slightly less efficient. The statistically significant differences were only observed during the first 13 days after the microtuber treatment. After that time, efficacy of ethanol and standard treatments was similar to control treatment with water. The investigated treatments had no effect on the natural decrease of ABA level in microtubers.