IN VITRO PROPAGATION OF TWO IRISH POTATO (Solanum tuberosum L.) VARITIES THROUGH LATERAL BUD CULTURE

Abstract

Irish Potato (Solanum tuberosum L.) is one of the world’s most economically important tuber crops belonging to the family Solanaceae. It is a versatile vegetable that is eaten all around the year. The objective of this study was to establish a protocol for in vitro micropropagation of Gudene and Belete Irish potato varieties from lateral bud explants. For shoot induction lateral buds of Gudene and Belete were cultured on MS basal medium that contained 30 g/l sucrose, 6 g/l agar, vitamins and supplemented with BAP in 1, 2, 3, 4 mg/l concentrations combined with different levels (0.5, 1, 1.5, 2 mg/l) of IAA. Shoot multiplication was done by culturing microshoots on full strength MS basal medium supplemented with BAP (0.5, 1, 1.5, 2 mg/l) and KN (0.5, 1, 1.5, 2 mg/l) in sole or combination. Rooting of the multiplied shoots was done on full strength MS basal medium supplemented with different concentrations of IBA (0.25, 0.5 0.75, 1 mg/l) and NAA (0.25, 0.5 0.75, 1 mg/l) in sole or combination. In all cases, MS basal medium without PGRs was used as control. The rooted plantlets were then acclimatized under greenhouse conditions by transplanting the plantlets on moist red soil, sand soil and compost or their mixture in 2:1:1 ratio. Results showed that shoot initiation, shoot multiplication and root formation responses were significantly (P<0.05) higher under all levels and combinations of hormones when compared with control treatments. There was significant difference between PGRs treatments in all measured parameters with 91.67% and 87.5% survived proliferating cultures seen for Gudenie and Belete varieties, respectively on shoot initiation MS basal medium supplemented with combination of 2.0 mg/l BAP and 1.0 mg/l IAA. Compared to the control, both BAP and KN alone or in combination showed significant positive effect on shoot multiplication of both varieties of Irish potato at all concentration levels. For Gudenie variety, 0.5mg/l BAP and 2mg/l KN combination had higher response than at other treatments. Number of days to shoot emergence was also found to be shorter at this level of hormonal combination than other treatments. In the case of Belete variety, 2mg/l KN alone treatment had similar effects as that of 0.5mg/l BAP and 2mg/l KN. Compared to the control, both IBA and NAA alone or in combination showed significant positive effect on root formation of shoots of both varieties. In both varieties, agronomic traits had significantly higher values at 1mg/l IBA to 0.25mg/l NAA combination treatment than other treatments. Number of days to root emergence was also found to be shorter at this level of hormonal combination than other treatments. The acclimatization experiment showed that plantlets of both varieties survived better on the sterilized mixture of moist red soil, sand and compost soil in a ratio of 2:1:1. Comparison of the performance of both varieties showed that Gudenie showed superior performance compared to Belete variety with respect to all measured agronomic traits, suggesting that varietal difference for the difference in the response to the PGRs.