KEY FINDINGS AND RECOMMENDATIONS • 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.

As part of a successful agronomic strategy, adequate nutrient management of the potato crop is essential throughout the whole growth period. In this review, the importance of balanced fertilisation for potato yield formation and yield security is addressed by taking advantage of the results of field trials and existing literature. The most important roles of the macronutrients nitrogen, phosphorous, potassium, magnesium, calcium and sulphur in the plant and their importance for yield formation in potato are reviewed. Fertilisation practices in potato production are discussed. Due to their various functions in plant metabolism, the impact of plant nutrients on potato yield is complex. Therefore, interactions with abiotic and biotic factors, for instance interactions between two different plant nutrients in the soil and the plant, are taken into account.

This report synthetizes the current state of knowledge about preferred characteristics for boiled potato among the different value chain actors; demand and profitability for the product in urban and peri-urban areas; and the agronomic practices and gender norms surrounding the potato product in Uganda. A literature review as well as key informant interviews were conducted to obtain information. From the findings, preferred physicochemical characteristics of raw and boiled potato are centered on appearance, color, size, texture and dry matter content. This can inform a more demand-oriented breeding by CIP and national partners. Potato is important for food and income generation for both men and women value chain actors, hence new potato varieties have been adopted in the different regions of Uganda. Across the value chain, the potato product has been found to be highly profitable.

Biofortification is a process of increasing the density of minerals and vitamins in a food crop through conventional plant breeding, genetic engineering, or agronomic practices (primarily use of fertilizers and foliar sprays). Biofortified staple food crops, when substituted consistently for non-biofortified staple food crops, can generate measurable improvements in human nutrition and health. This monograph describes the progress made in developing, testing, and disseminating biofortified staple food crops, primarily through the use of conventional plant breeding, summarizing the activities of two consortiums of inter-disciplinary collaborating institutions led the HarvestPlus program and the International Potato Center (CIP).

Biofortification is a process of increasing the density of minerals and vitamins in a food crop through conventional plant breeding, genetic engineering, or agronomic practices (primarily use of fertilizers and foliar sprays). Biofortified staple food crops, when substituted consistently for non-biofortified staple food crops, can generate measurable improvements in human nutrition and health. This monograph describes the progress made in developing, testing, and disseminating biofortified staple food crops, primarily through the use of conventional plant breeding, summarizing the activities of two consortiums of inter-disciplinary collaborating institutions led the HarvestPlus program and the International Potato Center (CIP). | PR | IFPRI5; HarvestPlus; CRP4; 2 Promoting Healthy Diets and Nutrition for all | HarvestPlus; A4NH | CGIAR Research Program on Agriculture for Nutrition and Health (A4NH)

Potato (Solanum tuberosam L.) is among the most important crops in the world. Potato in Uganda is mainly produced in the highland areas of Kabale and Kisoro in southwestern and Bugisu and Sebei areas on the slopes of Mt Elgon in eastern part of the country. However, the yields have continuously reduced due to a lack of suitable high-yielding and disease-resistant varieties coupled with poor agronomic practices and a poor potato seed system that limits the use of the good quality seed. The purpose of this study was to; i) identify high-yielding disease-resistant potato genotypes adapted to Mt Elgon region and ii) establish the effect of staggered planting on tuber yield and its influence on incidences and severities of late blight and bacterial wilt of potato. For the first objective, eight new potato clones were evaluated alongside ten released commercial potato varieties in Buginyanya for two seasons. Based on results from the first study, ten best performing genotypes (four clones and six commercial genotypes) were selected and evaluated at two different planting dates (staggering) for two seasons in two locations. Results showed significant differences (P<0.001) in tuber size, tuber uniformity, marketable tuber yield and the total tuber yield across all genotypes. Of all the potato genotypes evaluated 392797.22(17.4t/ha) Kinigi (17.2t/ha) and Rwangume (16.7t/ha) produced significantly (P<0.001) higher tuber yield compared to the local checks Rutuku (13.9t/ha) and Cruza (10.1t/ha). rAUDPC for Late blight (LB) showed significant differences (P<0.001) among genotypes. The most resistant genotypes were Kinigi (0.013) and 399985.39 (0.025) and the most susceptible were Bumbamagara (0.413) and 396036.201 (0.318) as compared to the local check Victoria (0.185). Genotype 396036.201(0.025) and Kinigi (0.027) were the most resistant for bacterial wilt while Kachpot (0.403) and Cruza (0.456) were the most susceptible to Bacterial wilt. Total tuber yield varied significantly (P<0.001) between sites and planting dates. Buginyanya yielded (17.3t/ha) more than Kapchorwa (11.05t/ha). The first planting (17.2t/ha) performed better than the second planting (11.4t/ha) across seasons and sites. Kapchorwa was more affected with LB compared to Buginyanya with the rAUDPC of 0.17 and 0.15 respectively. Buginyanya was more affected with Bacterial wilt (BW) compared to Kapchorwa with rAUDPC of 0.155 and 0.128 respectively. The first planting (0.177) was affected with both LB and BW compared to the second planting (0.143). Based on yield and disease data the best planting period for Buginyanya during the first season should be by end of April while in Kapchorwa during the first week of April and for season 2 in both sites planting should be done in the first two weeks of October. The most suitable genotype for first planting in Buginyanya is 392797.22, Kinigi, Victoria and 398208.704 while in the second planting genotypes Kinigi, Victoria, 398208.704 and 393385.39 can be planted. In Kapchorwa first planting genotypes 392797.22, Victoria, 393079.4, and Kinigi while for second planting is genotypes Kinigi, 398208.704 and 393079.4to be planted. Generally, genotype 392797.22, Kinigi, and Rwangume were the highest yielding and disease resistant hence recommended for release as commercial varieties or as donor parents for breeding program.

Potato is the fourth most important food crop in China. However, the yield is relatively low and the production is associated with high resource inputs and serious environmental problems. Potato production should be enhanced with sustainable practices that strike the right balance between multiple sustainable development objectives (agronomic, economic and environmental). The major aim of the present study was to explore the theoretical possibilities and demonstrate pathways for sustainable intensification of potato cultivation in China that optimize yield and quality, use natural resources efficiently, and minimize environmental impacts simultaneously. Crop modelling and farm surveys were used to assess these objectives at national and regional level, while on-farm experiments were performed to evaluate sustainable practices at local level.The biophysical potential of the potato crop in China was explored and the scope for enhancing yield was estimated. There is large potential to improve potato yield across the country under both irrigated and rainfed conditions (the yield gap is 66% and 61%, respectively, for irrigated and rainfed potato crops). A great improvement in yield can be achieved under rainfed conditions with current precipitation levels, especially in Qinghai and Heilongjiang in the north, and Guizhou in the southwest. Enhancing yield from actual to the potential yield level (under irrigated conditions) is associated with improved water productivity (from 7.9–22.3 to 30.7–54 kg dry matter ha-1 mm-1). Compared to the major cereals, potatoes have a larger potential to contribute to future food self-sufficiency in China as implied by the remarkable energy production gap (i.e., the additional calories provided by potatoes by closing the yield gaps to 80% of the potential yield under irrigated conditions and water-limited potential yield under rainfed conditions are 1.1 1014 and 0.9 1014 kcal calories, respectively).&nbsp;Improving environmental sustainability of potato cultivation should also be economically viable, and both yield and quality are key components driving the revenues for farmers. A framework was developed to assess the interrelationships between yield, quality and the influences on revenue. The framework was applied in a case study of commercial French Fries potato production in Inner Mongolia in the north. Farmers obtained low revenue (the gap between the revenue from the best performing farmers and actual revenue was 43%) as a consequence of moderate yield gap (the gap between the maximum farmers’ yield and actual yield was 26%) and poor tuber quality (i.e., low dry matter percentage of tubers, and high percentage of weight of the small-sized tubers). It was found that enhancing yield up to the maximum yield obtained by farmers in the case study (55 ton fresh matter ha-1) was strongly associated to improvement in quality and revenue, suggesting synergies for reaching different objectives.An integrated assessment on yield, resource use efficiencies (nitrogen use efficiency and water productivity) and environmental impacts (nitrogen surplus and water surplus) was performed for large-scale commercial farms in three major potato production regions in northern China (Inner Mongolia, Gansu and Heilongjiang). Potato production was associated with moderate resource use efficiencies (nitrogen use efficiency was 47–68%, and water productivity was 23–35 kg dry matter ha-1 mm-1) and substantial environmental impacts (nitrogen surplus was 50–156 kg ha-1, water surplus was 52–570 mm) due to the application of excessive amounts of fertiliser and irrigation. We assessed that a higher nitrogen use efficiency (exceeding 90% in the short-term and up to 84% in the long-term) was achievable with more efficient nitrogen management. Water productivity can be increased to 29–44 kg dry matter ha-1 mm-1, and water surplus can be reduced with more efficient irrigation systems.The pathways towards sustainable intensification were explored experimentally on large-scale commercial farms in Inner Mongolia in two years (2017–2018). In both years, irrigation contributed significantly to a higher yield and better quality in comparison with rainfed conditions. Under irrigated conditions, reducing nitrogen fertiliser from the current rates (189–252 kg ha-1) to lower levels (109–181 kg ha-1) did not affect yield nor quality, while it largely improved nitrogen use efficiency (from 67% to 89%) and reduced N surplus (from 81 to 28 kg ha-1). Yet, further reducing nitrogen fertiliser inputs (to 9–117 kg ha-1) should be done cautiously, accounting for different growing conditions of fields. Farmers found the reduction of nitrogen fertiliser input by 10–20% acceptable, while they noted that the widespread adaptation to more efficient irrigation practice (drip irrigation) was hindered by high cost and labor demands.&nbsp;The present study provides crucial knowledge and contextualized suggestions to underpin sustainable intensification of potato production in China.

The world population is projected to become 10 billion by the end of this century. This growing population exerts tremendous pressure on our finite food resources. Unfortunately, the lion-share of the global calorie intake is reliant upon a handful of plant species like rice, wheat, maize, soybean and potato. Therefore, it is the need of the hour to expand our dietary reliance to nutritionally rich but neglected, underutilized and yet-to-be-used wild plants. Many wild plants are also having ethnomedicinal and biocultural significance. Owing to their ecosystem plasticity, they are adapted to diverse habitats including marginal, degraded and other disturbed soil systems. Due to these resilient attributes, they can be considered for large-scale cultivation. However, proper biotechnological interventions are important for (i) removing the negative traits (e.g., low yield, slow growth, antinutritional factors, etc.), (ii) improving the positive traits (e.g., nutritional quality, stress tolerance, etc.), as well as (iii) standardizing the mass multiplication and cultivation strategies of such species for various agro-climatic regions. Besides, learning the biocultural knowledge and traditional cultivation practices employed by the local people is also crucial for their exploitation. The Special Issue “<i>Wild Crop Relatives and Associated Biocultural and Traditional Agronomic Practices for Food and Nutritional Security</i>” was intended to showcase the potential wild crop varieties of nutritional significance and associated biocultural knowledge from the diverse agroecological regions of the world and also to formulate suitable policy frameworks for food and nutritional security. The novel recommendations brought by this Special Issue would serve as a stepping stone for utilizing wild and neglected crops as a supplemental food. Nevertheless, long-term cultivation trials under various agro-climatic conditions are utmost important for unlocking the real potential of these species.