Comparison of Growth Habits of In Vitro Propagated Seed Corm among Taro (Colocasia esculenta Schott.) Cultivars and their Application for Semi-forcing Culture

Abstract

Characteristics of top growth and corm and cormel growth of four taro cultivars and one mutant line (obtained by tissue culture) derived from in vitro propagated seed corms (IP plants) were compared with plants growing from standard seed corms (ST plants). The growth habit of IP plants of Ishikawa-wase', an early maturing taro cultivar grown under a plastic house or a plastic tunnel in semi-forcing culture was also compared.
1. Although top growth of IP plants was inferior to that of ST plants in each cultivar and line, the growth of corm and cormel of IP plants was satisfactory; the ratios of corm and cormel fresh weights to whole plant fresh weight were higher in IP plants than in those of ST plants.
2. IP plants of the cultivars classified as cormel type, such as 'Uhan', 'Dotare', 'Wase-kohasubaimo', 'Ishikawa-wase' produced more cormels than did ST plants. But weight percormel of IP plants was lighter than that of ST plants.
3. In mutant line classified as corm type, IP plants showed better corm growth than ST plants. On the other hand, in cultivars of cormel type, IP plants produced less corm than did ST plants, and the ratio of edible part (total cormel weight to total weight of corm and cormel) was higher in IP plants than in ST plants.
4. There was no significant difference in growth habits of IP plants of 'Ishikawa-wase' obtained under semi-forcing and in open field culture.
5. It was observed that retardation of petiole extension, leaf mortality, and cormel growth tended to start earlier in IP plants than in ST plants.
6. From these results it is concluded that in vitro produced corm of early maturing cultivar may be useful as seed corm source for semi-forcing culture under a plastic house or a plastic tunnel.