Comparison of the growth of in vitro produced pathogen-tested Colocasia taro and field-collected planting material

In Fiji, taro (Colocasia esculenta Schott.) varieties grown in vitro from shoot tips, and pathogen-tested (PT) to meet guidelines for international transfer, were compared with field-collected (FC) plants over 3 years. For three varieties, 'Toakula', 'Samoa' hybrid, and 'Tausala ni Samoa', there were no significant differences between heights and corm yields of PT and FC plants. For a fourth variety, 'Samoa', PT plants outgrew FC plants and yields were more than double. This variety, considered best adapted to hill slopes, grew well in alluvial coastal soils after in vitro culture. A major change appeared to be in response to Dasheen mosaic virus infection. By the third trial, an average 13.2 of 18 FC plants per plot showed virus symptoms compared to 2.6 in PT plots; and whereas FC plants were stunted (0.75 m) and low yielding (5.4 t/ha) PT plants were similar in height and yield to the other varieties (1.11 in and 11.8 t/ha). The results could not be explained by the elimination of a second virus, Taro vein chlorosis virus from PT plants.