The planting of seed yam tubers for ware yam production can soon become a thing of the past! Single node yam vine seedlings from plants established in the aeroponics system (AS) are producing sizable ware yam tubers. The unexpected results may give rise to new horizons for yam production, exploration, and the development of the yam value chain in West Africa.
During the visit of executives of Iribov BV, Netherl ands and D. Invitro Labs Ghana Limited on 24 July, a 450 m 2 -portion of 1 ha of l and planted with AS single node vine seedlings of improved variety TDr 95/19177 on 16 November 2017 was harvested as a demonstration. Despite the dark green leaves of the yam plants showing potential for more growth, a total of 1,457 tubers weighing 643.6 kg were harvested. The two biggest tubers weighed 7.0 kg and 5.95 kg.
Such field performance attests to the viability and potential of pre-rooted AS single node vine cuttings. According to Norbert Maroya, YIIFSWA-II Project Leader, the plausible reason for this performance is that “Plants in the AS accumulate nutrients in their cells and when taken to a fertile field, they begin to express vigor in shoot and canopy development. Through photosynthesis, the starch produced translocates (moves) from the canopy and accumulates in the tubers. The more rapid the tuber development, the greater its final size. So basically, the longer the plants stay in the AS, the better the productivity of the vine seedlings.”
After 6 to 9 months of development in the aeroponics system, a plant can generate around 300 one-node vine cuttings. After 4 to 6 weeks in the nursery, they are transplanted to the field at a density of 1 m × 0.25 m where more than 92% of the rooted plantlets develop with vigor in the field and produce sizeable tubers in 6 months. So far, up to 30% of the tubers harvested of variety TDr95/19177 were above 1 kg.
“Our end goal is seed yam, but given the viability of the AS single node vine cuttings, some of our partners are rethinking the usefulness of planting single node seedlings in the field for ware yam production by influencing the duration in the field. Currently we are planting about 40,000 vine cuttings per hectare on ridges to attain a seed size and weight of about 250–300 g. With a high proportion of tubers weighing more than 1 kg, we are thinking of increasing the plant population to about 60,000 or 80,000 per hectare to control the size of tubers we are getting. We are also thinking of using the technique in potato by destroying foliage at 4 months after planting. With the AS vine seedling technology for seed yam tuber production we can, under irrigation, produce seed all year round,” Maroya said.
The project is currently working towards establishing 5 ha of seed yam using AS single node vine seedlings to demonstrate the possibility and potential of the high ratio propagation technologies (HRPT) developed in YIIFSWA for commercial seed companies. So far 2.1 ha has been planted with single node vine seedlings.
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