• Sweet potato yields have increased over the past decade partly due to introduction of improved high yielding varieties but yields still fall short of the potential. • Some of the factors constraining productivity growth include over-recycling of seed among farmers and poor agronomic practices due to limited extension services. • The release of Orange Fleshed Sweet Potato (OFSP) varieties have contributed to decline in Vitamin A deficiency in Malawi, contributing to improved nutrition status. • Demand for sweet potato and associated products is increasing partly due to increased urbanization and vulnerability of maize to climate change impacts. • To improve Malawi’s sweet potato value chain, the following recommendations are made: significant investments in seed systems, irrigation, post-harvest, value addition and agro-processing technologies in response to identified market and industry needs; investments in research and extension on improved varieties, good agronomic practices, and pest and diseases prevention and control; and investments to link farmers, farmer organizations and processors through contract farming arrangements and scaling up of Orange-Fleshed Sweet Potato (OFSP) varieties to maintain sufficient Vitamin A intake.

Acrylamide is a probable carcinogen found in processed potato products. The compound is formed at elevated temperatures by the Maillard reaction from two primary precursors - reducing sugars (fructose and glucose) and asparagine. Significant advances have been made in reducing acrylamide formation by selecting varieties with low precursor concentrations through conventional breeding or genetic modification techniques. However, acrylamide in many of the traditional varieties processed for fries or chips is sometimes found at elevated levels. Both agronomic and storage practices can significantly influence glucose, fructose, and asparagine concentrations and therefore the potential to form acrylamide during processing. This summary of a symposium presentation given at the 99th Annual Potato Association of American Meeting is to provide a general overview of previous studies that have examined the effects of agronomic factors such as nutrient and water management and storage factors such as temperature and duration on acrylamide precursors and/or acrylamide in processed potato products. A better understanding of how these factors affect acrylamide precursors is a first step in minimizing acrylamide formation during processing and improving the quality of processed potato products.

Surveys were conducted in the two main islands of Upolu and Savaii to determine the distribution and document the abundance of West Indian sweet potato weevil at different topographic areas in Samoa. A total of 28 farm localities were surveyed in August and October, 2016. Farm types, agronomic practices and farmer knowledge of the weevil were determined. About eighty percent of farmers were not aware of the presence of E. batataebecause of the lack of interest in sweet potato cultivation. Those that were aware of E. batatae commonly observed this pest in vines and rarely in tubers. It was also discovered that E. batataewas present in all levels of topography but inland areas had a higher weevil population as compared to coastal and highland areas. This indicates the influence of altitude on weevil population; lower altitudes have warm temperatures which are suitable for weevil population growth. Furthermore, this survey was carried out during the dry season and most sweet potato populations thrived in such periods compared to the wet season. Information gathered from this study would enable agricultural extension officers and farmers to become aware of the presence of E. batatae and to initiate control measures for it, if necessary.

Optimizing nitrogen (N) fertilizer management in irrigated potato (Solanum tuberosum L.) on coarse-textured soils is challenging. The “4R” nutrient stewardship framework of using N fertilizer at the right rate, right source, right placement and right time provides approaches to improve fertilizer use efficiency while maintaining or improving yield. This 3-years replicated field plot study evaluated effects from a series of N fertilization strategies including 10 combinations of sources, placement and timing, as well as fertigation, on irrigated processing potato (cv. Russet Burbank) grown for a total of five site-years in the Province of Manitoba, Canada. Treatments were designed to provide early to late availability of N to the potato crop. Nitrogen was applied to 80% of Provincial N recommendation to increase the likelihood of observing improved fertilizer use efficiency and effects of treatments on yields. Measurements were tuber yield, size distribution, specific gravity, hollow-heart rate, fertilizer apparent N recovery (ANR) and agronomic nitrogen use efficiency (NUE). Results showed differences in yield, quality, ANR and NUE between fertilizer treatments were generally very small or absent. Average tuber marketable yields for fertilizer treatments were significantly greater than those for the unfertilized control (P < 0.001). Split application of urea at planting and hilling, and urea at planting with fertigation occasionally increased tuber marketable yields on sites of coarse textured soils (P < 0.05). Use of polymer-coated urea (ESN) or stabilized urea with inhibitors (SuperU) did not affect yield, quality or N use of potato. Site-year difference (P < 0.001) were apparent for all measures highlighting the importance of soil and climatic conditions on agronomic and environmental effects of N management practices. The results indicate current grower practice of split urea application at planting and hilling and urea at planting following by in-season fertigation are sound. Results indicate growers could shift to the more convenient practice of ESN at planting without reducing yields. Absence of treatment effects suggests N was generally not a limiting factor for the current study, indicating that the current recommendation for potato production in Manitoba over-estimate site-specific crop N needs.

Potato (French fry, chipping, and fresh market) production is a dominant horticultural crop on the Canadian Prairies, and currently valued at $ 480 million (40% of Canada's potato production). Suitable cultivars and production practices are required to optimize yield, quality, and economic returns under the prevailing cool and short growing environment. This project examined advanced breeding clones and recently released cultivars of French fry, chipping, and fresh market potato, planted using whole, longitudinal-cut, and transverse-cut seed grown under irrigated and dryland production in comparison to industry standards. The growing season experienced favourable rainfall and temperature that resulted in above average yields. The French fry cultivar 'AAC Alta Strong' produced the highest marketable yield of 61.6 t ha-1, out-yielding the industry standard 'Russet Burbank' by 56%. Chipping cultivar 'Vigor' produced the highest yield of 49.6 t ha-1 and out-yielded the industry standard 'Atlantic' by 17%, and 'Snowden' by 39%. Fresh market cultivars and breeding clones produced similar yields averaging 47.4 t ha-1. Irrigation produced higher yields of French fry potato, but had no effect on chipping or fresh market types. Cut seed-pieces produced higher marketable yields than whole seed for French fry and chipping potato, whereas, seed type had no effect on fresh market yields. 'AAC Alta Strong', 'Snowden', and 'Milva' produced higher quality French fries, chips, and fresh market potato respectively. Tuber quality attributes were similar between irrigated and dryland production for all three market classes. These improvements in agronomic and quality traits translate into significant economic value-chain impact at three levels: producers (lower production cost, increased yield, and contractual premiums for quality attributes demanded by processors relative to the industry standard); processors (higher quality raw material for value-added products - French fries, chips, dehydrated, and canned); and consumers (quality and price).

The addition of orange-fleshed sweet potato (OFSP) to the food environment is an effective nutrition-sensitive agricultural approach to improve vitamin A intakes. However, the adoption of this biofortified crop merits further study. The objective of our research was to understand factors that affect Mozambican farmers’ adoption and retention of OFSP varieties, with a specific interest in the retention of planting material. Field research was conducted in three provinces of Mozambique during 2015. Provinces with different OFSP intervention histories were selected to allow for the identification of site-specific factors and the impact of variable approaches over time. Qualitative inquiry was used to assess participants’ progress through the five stages of the Innovation-Decision process in the Diffusion of Innovations Theory. Ninety-five producers, consumers, and market stakeholders of OFSP participated in semi-structured in-depth interviews and focus groups. Results indicate that diverse factors influenced the adoption and retention of OFSP, including organoleptic qualities, taste preferences, access to planting material, agronomic traits, environmental conditions, lack of capital for inputs and labor, unstable markets, and limited sharing of information and planting material across farmer networks. Current OFSP varieties were acceptable to Mozambican farmers and consumers, but there are several remaining challenges to reaching a critical mass such as lack of access to planting material, perceptions of superior drought tolerance of white-fleshed sweet potato (WFSP), and the belief that OFSP requires additional effort to cultivate (e.g. weed removal, measuring space between plants). Key recommendations which may be considered in future planning for OFSP interventions in Mozambique and other countries include enabling decentralized vine multipliers to provide vines to community members at no cost, continued focus on breeding and distribution of more drought tolerant varieties of OFSP, and training on the similarities in agronomic practices required for producing and preserving OFSP and WFSP.

Potato is highly productive crop and can provide a cheap and nutritionally-rich staple food. Its potential as a cash generator and source of food is much under-utilized in many emerging economies. In this paper we study the impact of an intervention that introduced improved potato technologies in Chencha, Ethiopia on the livelihoods of smallholder farmers. We collected information through in-depth interviews in order to explore possible pathways of impact on farmers’ livelihoods; and used this information as the basis for designing a household survey. The results show changes in agronomic practices and consumption; these changes were most pronounced among wealthy farmers who participated in the intervention. Farmers used the additional income from potato in different ways: wealthier farmers improved their houses and increased their livestock, whereas poor farmers mainly invested in furniture, cooking utensils, tools and in developing small businesses like selling and buying cereals, milk and weaving products in the local markets. Some wealthy farmers, who did not participate in the project, also derived some indirect benefits from the intervention. This underscores: i) interventions that promote uniform farming technologies in themselves are not always sufficient to improve the livelihoods of poor farmers, and ii) the need to broaden the scope of interventions so as to take into account the resources available to farmers in different wealth categories, and the diversity of strategies that they employ for improving their livelihoods. Our approach allows to understand and describe the different developmental effects of a single technological intervention on the different aspects of farmers’ livelihoods.

Estimating crop water productivity (CWP) for spatially variable climatic conditions in Egypt is important for the redistribution of crop planting to optimize production per unit of water consumed. The current paper aims to estimate maximum CWP trends under conditions of the Northern Nile Delta over three decades to choose crops that exhibit a higher productivity per unit of water and positive trends in the CWP. The Kafr El Sheikh Governorate was selected to represent the Northern Nile Delta Region, and mean monthly weather data for the period of 1985 to 2015 were collected to calculate standardized reference evapotranspiration and crop water use for a wide array of crops grown in the region using the CROPWAT8.0 model. The CWP was then calculated by dividing crop yield by seasonal water consumption. The CWP data range from 0.69 to 13.79 kg·m−3 for winter field crops, 3.40 to 10.69 kg·m−3 for winter vegetables, 0.29 to 6.04 kg·m−3 for summer field crops, 2.38 to 7.65 kg·m−3 for summer vegetables, 1.00 to 5.38 kg·m−3 for nili season crops (short-season post summer), and 0.66 to 3.35 kg·m−3 for orchards. The crops with the highest CWP values (kg·m−3) over three decades in descending order are: sugar beet (13.79), potato (w2) (10.69), tomato (w) (10.58), eggplant (w) (10.05), potato (w1) (9.98), cucumber (w) (9.81), and cabbage (w) (9.59). There was an increase in CWP of 41% from the first to the second and 22% from the second to the third decade. The CWP increase is attributed to a small decrease in water consumption and to a considerable increase in crop yield. The yield increases are attributed mainly to the planting of higher yielding varieties and/or the application of better agronomic practices

Estimating crop water productivity (CWP) for spatially variable climatic conditions in Egypt is important for the redistribution of crop planting to optimize production per unit of water consumed. The current paper aims to estimate maximum CWP trends under conditions of the Northern Nile Delta over three decades to choose crops that exhibit a higher productivity per unit of water and positive trends in the CWP. The Kafr El Sheikh Governorate was selected to represent the Northern Nile Delta Region, and mean monthly weather data for the period of 1985 to 2015 were collected to calculate standardized reference evapotranspiration and crop water use for a wide array of crops grown in the region using the CROPWAT8.0 model. The CWP was then calculated by dividing crop yield by seasonal water consumption. The CWP data range from 0.69 to 13.79 kg&middot;m&minus;3 for winter field crops, 3.40 to 10.69 kg&middot;m&minus;3 for winter vegetables, 0.29 to 6.04 kg&middot;m&minus;3 for summer field crops, 2.38 to 7.65 kg&middot;m&minus;3 for summer vegetables, 1.00 to 5.38 kg&middot;m&minus;3 for nili season crops (short-season post summer), and 0.66 to 3.35 kg&middot;m&minus;3 for orchards. The crops with the highest CWP values (kg&middot;m&minus;3) over three decades in descending order are: sugar beet (13.79), potato (w2) (10.69), tomato (w) (10.58), eggplant (w) (10.05), potato (w1) (9.98), cucumber (w) (9.81), and cabbage (w) (9.59). There was an increase in CWP of 41% from the first to the second and 22% from the second to the third decade. The CWP increase is attributed to a small decrease in water consumption and to a considerable increase in crop yield. The yield increases are attributed mainly to the planting of higher yielding varieties and/or the application of better agronomic practices.