Effects of Plant Growth Regulators on Tuber Dormancy and Sprouting of Potato (Solanum tuberosum L.) Varieties at Kulumsa, Southeast Ethiopia

Abstract

Potato production is constrained by shortage of seed tubers for different reasons among which extended potato tuber dormancy plays a significant role. The present study was conducted to evaluate the effects of plant growth regulators (PGRs) on dormancy and sprouting of seed tubers on potato varieties. Three PGRs viz. Gibberrelic Acid (GA₃), Benzyl adenine (BA) and Benzyl amino purine (BAP) each at two concentrations (0.1 and 0.2 mM) with distilled water (DW) as a control treatment were evaluated on tubers of two dominantly grown potato varieties (Jalenie and Belete) in Ethiopia. The treatments were laid out in a factorial experiment using Complete Randomized Design (CRD), with three replications. Thirty medium sized freshly harvested tubers of the two varieties per treatment were cleaned and soaked for 24 hrs in solutions of the three plant hormones at 0.1 mM and 0.2 mM. Likewise, tubers for the control treatment were soaked in distilled water for 24 hrs. The treated tubers were placed in separate plastic boxes, labeled and stored in a diffused light store (DLS). During the storage period, data were recorded every 10 days until 80% of the tubers showed visible sprouting (~2mm). The results showed all the PGRs significantly (p<0.05) affected tubers' dormancy and sprouting at different concentrations compared to the un-treated control (DW). Compared to BAP and BA, GA₃ at low concentration (0.1mM) highly shortened tubers' dormancy period of both varieties while Jalenie sprouted earlier than Belete. In addition to tuber's dormancy, GA₃ significantly (p<0.05) increased the number of sprouts per tuber, length of apical dominance, length of lateral branching of sprout, and fresh and dry weight of tubers' sprouts. The highest increment of the aforementioned measurements was recorded at 0.1 mM GA₃ although differences were observed between the two varieties. Therefore, GA₃ at 0.1 mM could be recommended as the best PGR to shorten tubers' dormancy of both varieties after harvest. Using GA₃ treatment as a pre-sprouting hormone could double/ or triple the number of seed tuber production cycle per season with supplementary irrigation depending up on the need. Nevertheless, for conclusive recommendation, additional study is needed to know the profit margin of using GA₃ at the optimum concentration for large scale seed production.

Keywords: Plant Growth Regulators, Potato, Seed potato store, Tuber dormancy

DOI: 10.7176/JBAH/12-3-01

Publication date: February 28^th 2022