Current and potential systems for maintaining sweetpotato planting material in areas with prolonged dry seasons : a biological, social and economic framework

• Main Author: Namanda, Sam
• Other Authors: Gibson, Richard; Rees, Deborah
• Published: University of Greenwich 2012
• Subjects: 635; SB Plant culture
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616525

This study on sweetpotato seed systems was conducted in Mukono, Kamuli, Bukedea and Soroti districts in Uganda, and in Mwanza, Shinyanga and Meatu regions in the Lake Zone of Tanzania during 2007 – 2011. It aimed at developing simple, affordable and applicable technologies for conserving and multiplying sweetpotato planting material for early season planting after the long dry season. The study sought to understand and describe farmers’ existing approaches, improve on rapid multiplication techniques and develop rational use of available planting material. Complete lack of or insufficient planting material for early planting immediately following the long dry season was reported. Farmers recognised that obtaining planting material early was beneficial as it resulted in increased root yield, an early source of food and sales at high prices. The Triple S (Sand, Storage and Sprouting) method of producing ample planting material for early season planting was developed in Uganda after testing various ways of storing the roots during the dry season so as to eliminate dry season mortality. Using roots obtained from crops planted in the conventional time and planting them out in watered gardens 1-2 mths before the rains to act as sources of sprouts for vine cuttings was the most appropriate. The method was validated in Tanzania which has a longer dry season. The use of 20cm cuttings instead of the mini cuttings (10 cm) in rapid multiplication of vines needed less labour and care. Pre-planting fertiliser (NPK: 25:5:5) doubled the quantity of planting material generated, and planting shorter and fewer cuttings than recommended saved planting material to enable more extensive plant coverage and doubled potential production. All these findings greatly contribute to the improvement of the conservation and multiplication of planting material, especially to improving the availability of early planting material.