Comparative study of indigenous Vigna vexillata (L.) A. Rich. accessions from different latitudes in Indonesia and Australia

A comparative study was conducted of the growth and development of 12 wild accessions of Vigna vexillata from a range of locations from eastern Indonesia to south-eastern Australia. In anticipation that accessions from different latitudes may exhibit differential adaptive photoperiodic response, the plants were exposed to a range of extended photoperiods during their growth. There was significant variation among the accessions for a wide range of traits, although differences in phenology were relatively smaller than those in vegetative biomass and seed and tuber yield. Accessions that produced more vegetative biomass tended to produce more tuber biomass but smaller seed yields. While average biomass production was similar between the Indonesian and Australian accessions, the former tended to produce less seed and smaller tuber biomass. There were no consistent relations between phenology and latitude of provenance. Nor were there any apparent relations between latitude and biomass or latitude and seed yield. However, both the tuber dry weight and the tuber harvest index were progressively greater in accessions from higher latitudes. There were no apparent effects of extended day length on phenology. However, longer days tended to promote vegetative development and reduce partitioning to seeds and tubers, consistent with short-day photoperiodic response. It is suggested that flowering was unaffected by photoperiod treatments because the plants were induced to flower by the short late-winter day-lengths before the treatments were applied. Consistent with this explanation, all plants in all treatments flowered and set pods quickly in all treatments