Improved propagation methods to raise the productivity of yam (Dioscorea rotundata Poir.)

Abstract

White Guinea yam (Dioscorea rotundata Poir.) is an important staple to millions of people in West Africa. Obtaining good quality planting material for yam cultivation is a major challenge. Multiplication ratios are low, and seed tubers are prone to contamination with pests and pathogens in the traditional systems of production. Some approaches to producing quality seed of yam are as follows: farmers select small whole tubers from a ware crop harvest; stimulate the production of seed tubers by 'milking' ware tubers while the leaves of the plant are still green (double harvest system); cut ware tubers into setts about the same sizes as regular seed tubers; or use the 'Anambra' system where smaller setts are cut and used to produce seed tubers. New methods that have been developed to address some of the challenges of quantity and quality of seed tubers are not yet widely applied, so farmers continue to use traditional methods and save seed from a previous harvest to plant the ware crop. This document presents an overview of traditional and modern methods of seed yam production and gives a perspective for the future. Among the modern methods of seed yam production, only the minisett technique, which uses 25-100 g tuber pieces, is currently used at farmer level, although on a limited scale. While tissue and organ culture techniques are the most rapid methods of multiplying disease free propagules, their limitations include high costs, need for skilled personnel and specialized equipment. The aeroponics and temporary immersion bioreactor methods of producing seed yam are relatively new, and still need more research. To build and sustain a viable seed yam production system, a multiplication scheme is required that combines two or more methods including tissue culture for cleaning the seed stock.

The Effect of Soil Types on the Growth Rate of Yam Seedlings Inferred from 2-D Electrical Resistivity Tomography

“…However, the effect of water-holding capacity is high for lateritic clayish soil than the other soil types, which retards growth of yam seedlings. This is because yam growths are enhanced under moderate soil moisture, sufficient nutrient supply and well-structured soil (Aighewi et al, 2015). Result also show low growth rate of yam seedlings in compacted loamy-sandy soil (crop marker 4) compared to the uncompacted loamy-sandy soil (crop marker 5).…”

Using Surface Response Models to Evaluate the Effects of Kinetin on Dioscorea alata Propagated in Vitro

“…Production cycles can therefore be well planned, as well as clean, high quality and uniform plants can be produced [15]. Tissue culture provides a rapid method of multiplying disease-free and improved cultivars for production, breeding programs and research work [5]. Additionally, tissue culture is very essential for germplasm conservation of vegetative propagated crops, alleviating losses from pests and diseases, drought stress, wild fires and thefts associated with field conservation, especially in developing countries [14,16].…”

“…The world production of yam in 2014 was 68.1 million tons, with West Africa producing more than 91% [4]. According to Aighewi et al [5], Dioscorea alata is the second most important edible species of the genus Dioscorea, which has over 600 species. Most D. alata cultivars are late-maturing with long shelf-life, thus D. alata helps to fill the demand for yam food when all other yams are out of season [6,7].…”

“…In West Africa, most farmers use tubers saved from previous season for propagation. These are often prone to pests and diseases, leading to poor yield and quality [5,11]. Moreover, yam propagation by this method is slow and inefficient for rapid multiplication.…”

Relative efficiency of positive selection and tissue culture for generating pathogen-free planting materials of yam (Dioscorea spp.)

“…are starchy root staples and a primary source of income in West Africa (Aighewi et al 2015). About 58 million tons are produced annually worldwide, 93% and 65% of which are produced in West Africa and Nigeria, respectively (FAO 2013).…”