Are dormancy management and physiological age the achilles' heel of aeroponic minituber production in seed potato value chains in SSA?

Scarcity of good quality seed is major obstacle to expanded potato (Solanum tuberosum L.) production in sub-saharan Africa (SSA). Constraints in availability and supply of seed potato are partly attributable to challenges in production of pre-basic which is an intermediary step necessary in production of seed tubers in the seed potato value chain. Aeroponic minutuber production is a relatively recent technology that has the potential to break the seed potato bottleneck in many SSA countries due to several advantages that it holds especially those related to high multiplication rates; typically (1:50-100) that arise from sequential harvesting. There are, however, a number of potential challenges which, if not addressed, can contribute to non attainment of the projected increases in seed availability and not only mess up the 3 generation (3G) revolution strategy of boosting seed tuber production in SSA but also jeopardize the adoption of the technology. Besides problems associated with failure of electricity supply and management of nutrition, the Achilles‘ heel of aeroponic minituber production is probably the large variation in physiological age of resulting tubers due to sequential harvesting that takes place over several months during the production cycle. In the absence of cold storage facilities which are few and beyond the reach of many pre-basic seed potato growers in many SSA countries, harvested minitubers can either be at dormant, apical dominance, multiple sprouting or senile stage when they are required for planting with significant impacts on subsequent yields. This paper discusses the problems associated with physiological age in seed tuber systems based on aeroponic minitubers and proposes some approaches that may overcome these challenges to ensure that the promise of aeroponic minituber production is realized. The proposed approaches include the strategic application of dormancy inhibiting and dormancy promoting substances at various stages of aeroponic minituber production combined with the use of low cost storage systems such as the diffused light storage technology depending on the dormancy period of the variety (ies) being grown

How big is the potato (Solanum tuberosum L.) yield gap in Sub-Saharan Africa and why? A participatory approach.

According to potato experts from ten Sub-Saharan Africa (SSA) countries working together in a community of practice (CoP) over a 3-years period, potato farmers across SSA can increase their current annual production of 10.8 million metric tons by 140% if they had access to high quality seed along with improved management practices. This paper describes this innovative new methodology tested on potato for the first time, combining modelling and a comprehensive online survey through a CoP. The intent was to overcome the paucity of experimental information required for crop modelling. Researchers, whose data contributed to estimating model parameters, participated in the study using Solanum, a crop model developed by the International Potato Center (CIP). The first finding was that model parameters estimated through participatory modelling using experts’ knowledge were good approximations of those obtained experimentally. The estimated yield gap was 58 Mg ha-1, of which 35 corresponded to a research gap (potential yield minus research yield) and 24 to farmers’ gap (research yield minus farmer’s yield). Over a 6-month period, SurveyMonkey, a Web-based platform was used to assess yield gap drivers. The survey revealed that poor quality seed and bacterial wilt were the main yield gap drivers as perceived by survey respondents

Yield stability analysis of promising potato clones in mid and high altitude regions of Kenya

Eleven promising potato clones possessing late blight tolerance were evaluated for tuber yield performance, stability and adaptation across ten environments of medium and high potential potato growing regions of Kenya. Results of combined analysis of variance for tuber yield showed significant effects of genotypes, environments, and genotype by environment interaction. The mean tuber yield for individual clones ranged from 22.80 to 37.63 t ha-1. When the genotypic tuber yields were subjected to stability analysis against an environmental index, the regression coefficients for individual clones ranged between 0.427 and 1.687. Among the clones tested, KP90188.3 was the most stable genotype across all the ten environments, while four of the highest yielding clones; 387792.5, 378699.2, 381381.20 and 381381.13 appeared to be specifically adapted to favourable growing conditions. Two clones, 381381.13 and 381381.20 exhibited mean superior performance in yield across all environments, and were pre-released in 1996 pending multiplication of sufficient quantities of seed.Onze clones prometteurs de pomme de terre ayant une tol\ue9rance au mildiou ont \ue9t\ue9 \ue9valu\ue9s pour performance en rendement des tubercules, la stabilit\ue9 et l'adaptation dans dix environnements \ue0 potentiel moyen et \ue9lev\ue9 pour la production de la pomme de terre au kenya. Les r\ue9sultats de l'analyse combin\ue9e de la variance du rendement en tubercules ont mis en \ue9vidence des effets significatifs des g\ue9notypes, des environnements, et de l'interaction entre g\ue9notype et environnement. Le rendement moyen en tubercules pour les clones individuels varie de 22, 8 \ue0 37, 6 t ha-1. Lorsque les rendements g\ue9notypiques de tubercules \ue9taient soumis \ue0 l'analyse de la stabilit\ue9 contre un indice environnemental, les coefficients de r\ue9gression pour les clones individuels variaient de 0, 427 \ue0 1,687. Parmi les clones test\ue9s, KP 90188.3 \ue9tait le g\ue9notype le plus stable dans tous les environnements, alors que quatre des clones 387792.5, 378699.2, 381381.20 et 381381.13 semblaient sp\ue9cialement adapt\ue9s aux conditions favorables de croissance. Deux clones, 381381.13 et 381381.20, ont montr\ue9 une performance moyenne sup\ue9rieure \ue0 travers tous les environnements. Ils \ue9taient pr\ue9-diffus\ue9s en 1996 en attendant la multiplication des quantit\ue9s suffisantes de semences

Yield stability analysis of promising potato clones in mid and high altitude regions of Kenya

(African Crop Science Journal, 1998 6(2): 137-142

Constraints to commercializing potato in Kenya.

Although potato is an important source of food and income in Kenya, poor yields and erratic returns have constrained profitability and expansion of the crop. The objective of this study was to describe the potato production system, identify constraints, and determine levels of use of inputs; and the profitability of potato as a business in 4 out of the 10 most important potato producing Counties. We used multistage sampling to select 390 farmers from 4 of the 10 most important potato producing Counties. A questionnaire was used to collect information from farmers and means were separated using ANOVA. Results showed that farming was the main source of income for both husband and wife in at least 66% of households and these where fairly young families with the household heads aged 45 years; having 15years of experience in potato production, and having had 13 years of schooling-with significant differences across regions. Potatoes were grown principally by small-holder farmers twice a year on about 0.92 acres in the March/May season and 0.87acres in the September/October season with significant differences across regions. There was uniformity in variety choice with Changi being predominant in three out of the four Counties. Productivity was at a sub-optimal level with yields of 5.6tons/ha compared to an African average of 10.8tons/ha (CIP 2007) - with significant regional differences. The low productivity can be partially explained by the low input use (seed and fertilizer) which was well below what was recommended by the Government extension officers. The quality of the seed used was of doubtful quality as it was not certified seed but sourced mainly from own harvest, from neighbors or from nearby primary markets. Despite all these shortcomings potato production gave farmers a gross income of about $1240 in the March/May season and$1173 in the Oct/Sept and this was above the UN poverty level of $1.5 per day (or approx.$270 per season of 6 months) -with that income differing significantly across regions. Potato thus has the potential to significantly impact the food and income situations of small-holder farmers in Kenya if the identified constraints can be addressed in socially and economically acceptable ways