Yam Seedsor

Yam Seedsor

Yam Seeds

Scaling breakthroughs in seed multiplication technology is expected to increase the productivity of yam cultivation by up to 30% in Ghana and Nigeria. The Yam Improvement for Income and Food Security in West Africa II (YIIFSWA-II) project, led by the International Institute of Tropical Agriculture (IITA), is using aeroponic propagation technology to address the increasing demand for high-quality and improved varieties of seed yam in the region.


Yam is a staple crop in West Africa. At least 1.6 million people directly depend on the yam value chain for their livelihoods. Yet, seed yam markets remain underdeveloped for reasons such as outdated seed production methods, poor distribution networks and lack of quality assurance systems. Traditional methods of seed yam production are expensive and inefficient, requiring farmers to save 25 to 30% of their harvest to plant tubers the following season. This not only reduces farmers’ incomes from harvests, but the saved seeds are often diseased, producing significantly lower yields each year. However, scientists working on the €11.32 million funded YIIFSWA project have successfully used an aeroponics system (AS) to rapidly multiply large quantities of desired varieties of seed yam tubers in a clean and cost-effective process.Yam plantlets are planted in AS boxes and grown in a purely air or mist environment, without soil or any other aggregate medium, to produce mini-tubers. The results from YIIFSWA-I showed a 95% success rate in AS yam propagation and the multiplication rate was about 30 times faster than traditional seed yam production. The AS pruned vines start producing shoots within 2 weeks of being planted, whilst normal vines from field plants take 4-6 weeks to develop shoots. The process also reduces disease in yam crops as no soil-borne pests and diseases can infect the plants whilst they develop into mini-tubers. This is particularly vital given that national agricultural research and extension systems (NARES) were at risk of losing seed stocks of improved yam varieties due to pathogen infestation. “Yam is an important crop in Africa and addressing the seeds’ constraints will go a long way in improving the livelihoods of farmers who depend on the crop,” states Dr Robert Asiedu, IITA director for West Africa, in reference to the achievements of YIIFSWA-I.

Yam plants have thick tubers (generally a development of the base of the stem) which often have thick, almost barklike skin. The long, slender, annual, climbing stems bear lobed or entire leaves that are either alternate or opposite. The unisexual flowers are borne in long clusters. The flowers are generally small and individually inconspicuous though collectively showy. Each consists of a greenish bell-shaped or flat perianth of six pieces, enclosing six or fewer stamens in the male flowers and surmounting a three-celled three-winged ovary in the female flowers. The ovary ripens into a membranous capsule, bursting by three valves to liberate numerous flattish or globose seeds.Yam crop begins when whole seed tubers or tuber portions are planted into mounds or ridges, at the beginning of the rainy season. The crop yield depends on how and where the sets are planted, sizes of mounds, interplant spacing, provision of stakes for the resultant plants, yam species, and tuber sizes desired at harvest. Small-scale farmers in West and Central Africa often intercrop yams with cereals and vegetables. The seed yams are perishable and bulky to transport. Farmers who do not buy new seed yams usually set aside up to 30% of their harvest for planting the next year. Yam crops face pressure from a range of insect pests and fungal and viral diseases, as well as nematode. Their growth and dormant phases correspond respectively to the wet season and the dry season. For maximum yield, the yams require a humid tropical environment, with an annual rainfall over 1500 mm distributed uniformly throughout the growing season. White, yellow, and water yams typically produce a single large tuber per year, generally weighing 5 to 10 kg (11 to 22 lb). (Source: en.wikipedia.org)


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