In Vitro Tuberization of Two Potato (Solanum tuberosum L.) Varieties Grown in Southeastern Ethiopia

Abstract

The conventional propagation of potato (Solanum tuberosum L.) has major problems of low multiplication rate and high chance of disease dissemination. In vitro propagation is a better alternative to address limitations of conventional propagation method. This study was initiated to optimize protocol for in vitro tuberization of potato varieties (Ararsa and Hunde) using single nodal explants. Two independent experiments: in vitro multiplication and in vitro tuberization were laid out in a completely randomized design with factorial arrangements. For in vitro multiplication, initiated nodal explants (2cm length) were cultured on Murashige and Skoog medium (MS) containing different combinations of BAP (0.0, 0.5 and 1mg/l) and NAA(0.00, 0.01, 0.02, 0.03mg/l), 30g/l sucrose, 0.1mg/l GA3 Key words: in vitro tuberization, microtubers, Potato and Sucrose ix and 8 g/l agar. For in vitro tuberization, plantlets were transferred to MS medium supplemented with 40, 60, 80, 100 and 120g/l of sucrose. Data were subjected to analysis of variance (ANOVA) and significant means were separated using The Ryan-Einot-Gabriel-Welsch (REGWQ) Multiple Range Test at α = 5% significant level. ANOVA showed a highly significant interaction (p <0.0001) among BAP, NAA and variety in shoot multiplication. It was found that MS medium supplemented with 1mg/l BAP plus 0.01 mg/l NAA gave maximum average shoot length (4.43 ± 0.07cm), number of shoots (5.00 ± 0.10) per explant and nodes per shoots (4.20 ± 0.01) for Ararsa. Variety Hunde gave maximum shoot proliferation and growth at 0.5mg/l BAP plus 0.01mg/l NAA. The variety and sucrose interaction had highly significant interaction on microtuber induction. Both varieties performed better on in vitro tuberization on MS medium supplemented with 60g/l sucrose. Maximum average microtuber number (1.97 ± 0.02) per explants, microtuber diameter(3.60 ± 0.04 mm) and weight (0.08 ± 0.002g) were obtained from Ararsa, after 42.67±0.58 days, when MS medium was supplemented with 60g/l sucrose. Variety Hunde, on the other hand, gave average microtuber number (2.90±0.031), microtuber diameter (2.81 ± 0.015mm) and microtuber weight (0.06 ± 0.002g) on the same medium. Thus, the use of this protocol could serve as a starting point for in vitro tuberization in Ethiopia. Culturing plantlets on different concentrations of BAP in combination with sucrose may be helpful to improve the size of microtubers.