Browsing by Author "Kwambai, Thomas K."

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    Dormancy and Physiological Age of Seed Tubers from a Diverse Set of Potato Cultivars Grown at Different Altitudes and in Different Seasons in Kenya
    (Springer Link, 2023-02-09) Kwambai, Thomas K.; Griffin, Denis; Nyongesa, Moses; Byrne, Stephen; Gorman, Monica; Struik, Paul C.
    The study was conducted to determine the dormancy and physiological age characteristics of diverse potato genotypes as influenced by growing altitudes and seasons for future breeding strategies and optimal patterns of use. Dormancy and sprouting characteristics have an impact on tuber production, storability and seed quality for planting and ware for consumption and the market. This study presents the results of dormancy and physiological age measurements conducted on 47 potato genotypes grown at three altitudes with three replications at each location and in two contrasting growing seasons. The seed tubers were evaluated at low altitude under darkness on moist sand storage conditions to assess their dormancy release, number of sprouts, sprout weight, sprout length and percentage tuber weight loss. Results showed significant (p < 0.001) differences among genotypes, locations and seasons, and significant interactions between these factors for days to dormancy release, number of sprouts per tuber at dormancy release and at 45 days after dormancy release, length of longest sprout, weight loss percentage of unsprouted and sprouted tubers at dormancy release and at 45 days after dormancy release, respectively. There was a wide variation in time to dormancy release (54 to 136 days); most genotypes showed medium to long dormancy. Seed tubers grown at low altitude showed longer dormancy than those grown at higher altitudes, while genotypic differences in dormancy were very consistent across environments. Genotypes strongly differed in sprouting characteristics and weight loss. There were highly significant interactions between altitude and season for all variables assessed, except for the number of sprouts 45 days after dormancy release and the weight loss after sprouting. Generally, the genotypic effects were larger than those of altitude, season and the interaction effects for all variables evaluated. This paper will allow variety selection to optimize seed quality at planting and minimize storage losses while providing new targets for breeders.
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    Seed Quality and Variety Preferences Amongst Potato Farmers in North-Western Kenya: Lessons for the Adoption of New Varieties
    (Springer Link, 2023-06-03) Kwambai, Thomas K.; Griffin, Denis; Struik, Paul C.; Stack, Laura; Rono, Selly; Brophy, Caroline; Nyongesa, Moses; Gorman, Monica
    Potato (Solanum tuberosum L.) is an important commercialised food crop in Kenya. Recently, Kenya has realised a huge increase in the number of formally released potato varieties. The performance of these varieties is not clear and their adoption across various growing environments is low. This study explored how availability, access, quality and systems of seed and storability and market demand of potatoes influence farmers’ decisions on choice of varieties they grow and how they select seed for planting in the different seasons. Focus group discussions (83 farmers) and a household survey (225 farmers) were conducted in three major potato growing areas (Lelan, Saboti and Kaptama) in north-western Kenya. Results showed that farmers mainly used farm-saved seed and only 4.9% had used certified seed, while 71% indicated that certified seed was not available locally. Almost all farmers ensured they used healthy seed by visually examining the seed tubers while most farmers also examined the health of the crop in the field before harvest. Farmers renewed their seed depending on the number of cycles used, infection, decline in yield and availability of clean seed. Seed was usually renewed for up to after 5 years of recycling, and generally involved the varieties Shangi, Kabale and Arka. Farmers ranked five variety traits: tuber yield, disease resistance, market demand, early maturity and storability as most important in the choice of a variety. Farmers understood the importance of dormancy and had methods for managing dormancy, but their knowledge was biased to the few varieties they had, particularly Shangi, the predominant variety in the market. Despite agronomic attributes, market demand featured as a primary determinant of variety choice amongst farmers. The findings from this paper can guide use of seed, adoption of new varieties and future breeding of potato varieties for Kenya.
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    Seed Quality and Variety Preferences Amongst Potato Farmers in North-Western Kenya: Lessons for the Adoption of New Varieties
    (Springer, 2023-04-16) Kwambai, Thomas K.; Griffin, Denis; Struik, Paul C.; Stack, Laura; Rono, Selly; Brophy, Caroline; Nyongesa, Moses; Gorman, Monica
    Potato (Solanum tuberosum L.) is an important commercialised food crop in Kenya. Recently, Kenya has realised a huge increase in the number of formally released potato varieties. The performance of these varieties is not clear and their adoption across various growing environments is low. This study explored how availability, access, quality and systems of seed and storability and market demand of potatoes infuence farmers’ decisions on choice of varieties they grow and how they select seed for planting in the diferent seasons. Focus group discussions (83 farmers) and a household survey (225 farmers) were conducted in three major potato growing areas (Lelan, Saboti and Kaptama) in north-western Kenya. Results showed that farmers mainly used farm-saved seed and only 4.9% had used certifed seed, while 71% indicated that certifed seed was not available locally. Almost all farmers ensured they used healthy seed by visually examining the seed tubers while most farmers also examined the health of the crop in the feld before harvest. Farmers renewed their seed depending on the number of cycles used, infection, decline in yield and availability of clean seed. Seed was usually renewed for up to after 5 years of recycling, and generally involved the varieties Shangi, Kabale and Arka. Farmers ranked fve variety traits: tuber yield, disease resistance, market demand, early maturity and storability as most important in the choice of a variety. Farmers understood the importance of dormancy and had methods for managing dormancy, but their knowledge was biased to the few varieties they had, particularly Shangi, the predominant variety in the market. Despite agronomic attributes, market demand featured as a primary determinant of variety choice amongst farmers. The fndings from this paper can guide use of seed, adoption of new varieties and future breeding of potato varieties for Kenya.
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    Understanding Genotype × Environment Interactions in Potato Production to Guide Variety Adoption and Future Breeding Strategies
    (Springer Link, 2023) Kwambai, Thomas K.; Struik, Paul C.; Gorman, Monica; Nyongesa, Moses; Rop, Wilfred; Kemboi, Edward; Griffin, Denis
    Potato (Solanum tuberosum L.) is a versatile crop given its adaptation, production capacity and utilization, and therefore valuable in many different countries. In Kenya, potato is mainly grown by smallholder farmers for food and cash. Access to quality seed of adapted and acceptable varieties was limited. This led to public–private partnerships with European seed companies working independently or with their Kenyan counterparts in introducing high-quality seed of new varieties. Some of these showed improved yield, quality and disease resistance. However, some European varieties were less adapted to the short photoperiods prevailing in Kenya than the late blight-resistant elite clones from South America, introduced by the International Potato Center (CIP). Traits that influence genotype adaptation can aid breeding cultivars or support their recommendation for certain production areas, but such traits have not been studied in detail for Kenya. This study sought to understand the adaptation of 50 contrasting genotypes from Europe, CIP and Kenya and the traits driving adaptation to four seasons and three altitudes. Genotypes showed a wide range of yields in all environments studied. The factor genotype explained most of the variance for total tuber yield (71.2%), plant height (49.3%) and area under the disease progress curve (25.1%) based on the Wald statistic, followed by season and the genotype by altitude interaction. Other traits studied hardly contributed to the understanding of the responses to the twelve testing environments. However, the largest proportions of variances for days to 50% emergence, days to maturity and canopy cover were accounted for by altitude.
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    Understanding Potato Production Practices in North-Western Kenya through Surveys: an Important Key to Improving Production
    (2023-09-01) Kwambai, Thomas K.; Struik, Paul C.; Griffin, Denis; Stack, Laura; Rono, Selly; Nyongesa, Moses; Brophy, Caroline; Gorman, Monica
    Potato is the second most important food crop after maize in Kenya. However, most farmers produce potatoes under sub-optimal management, resulting in low yields, despite the introduction of improved varieties. Potato production practices were documented and compared to contribute towards improved potato management and productivity in Kenya. The study was guided by the hypothesis that potato farming and management practices influence potato performance and can depend on the production environment. Focus group discussions and household surveys were conducted in three major potato growing areas in Kaptama, Saboti and Lelan in Bungoma, Trans Nzoia and Elgeyo Marakwet counties in Kenya. Farming was the main occupation of 58.2% of the respondents. Respondents across the study sites indicated that they grew potatoes with their main focus as a cash (83.6%) and food (16.4%) crop. Most respondents had planted potatoes during both the last long (96.4%) and short (92.4%) rainy seasons. The four most important constraints limiting optimal potato production according to respondents were lack of quality seed, diseases (specifically late blight and bacterial wilt), poor marketing and lack of adequate technical knowledge on potato management. Low yields realized by farmers were mainly influenced by poor farmer practices in the use of seed, fertilizers, pesticides and crop rotation. This was compounded by farmers’ perceptions on input quantities applied, frequencies and farmers’ access to agricultural extension information on potatoes, which heavily relied on family members and neighbouring farmers. Provision of quality seeds and training of farmers with the support of demonstrations on fertilizer and pesticide and appropriate crop rotation practices are recommended for improved potato production and yields. Use of irrigation where possible should be enhanced through government and development partners’ support to ensure sustainable potato production and supply. Also, the use of viable extension information channel(s) could enhance potato production for household food security, livelihoods and national goals.