Responses of Moringa oleifera root growth to container size during overwintering in temperate regions

Due to its fast growth rates, Moringa oleifera is being grown as an annual crop in temperate areas with freezing winter temperatures. Seedlings are raised under greenhouse conditions for overwintering and then transplanted outside at the beginning of spring, which allows for several cuttings prior to onset of the subsequent winter. However, there is limited information on container-size for overwintering of M. oleifera seedlings under greenhouse conditions. The objective of this study was to determine the responses of M. oleifera root growth to different container-sizes during overwintering in temperate regions under greenhouse conditions. Uniform two-month old seedlings were hardened-off and transplanted into five different container-sizes, measured in volume. Seedlings were fertilised once at transplanting and irrigated through scheduling with moisture meter. Six months after the treatment, container-size had highly significant effects on root length and crown girth, contributing 91 and 60% to total treatment variation of the respective plant variables. Root length and container-size exhibited quadratic relations, with optimum container-size computed to be 300 ml. In contrast, crown girth and container-size exhibited linear relations. In conclusion, the findings in this study suggested that a much smaller container (300 ml) than the one currently used (750 ml) would allow optimum overwintering of M. oleifera seedlings, thereby reducing production costs. Key words: Container-cost, crown girth, labour-cost, Moringa species, shoot dormancy, root development.