RESUMEN La papa es un cultivo originario del Perú con amplia diversidad genética y que actualmente se desarrolla en pequeñas parcelas en más de 300 mil hectáreas a nivel nacional generando empleo rural. Por ello es prioritario evaluar la sustentabilidad de los sistemas de producción en concordancia con prácticas agronómicas que sean amigables al medio ambiente. Se realizó una investigación para determinar el efecto que podría tener la inoculación de cepas bacterianas nativas sobre el comportamiento agronómico de la papa en fincas productoras de la región Lima. Se instalaron ensayos agronómicos en condiciones de campo bajo el Diseño de Bloques Completos y se evaluaron características agronómicas y productivas del cultivo. Previamente, se determinó el grado de sustentabilidad ambiental de las fincas productoras de papa en Lima, mediante el análisis multicriterio de Sarandón. Se concluyó que las fincas tienen un bajo nivel de sustentabilidad ambiental, con un valor de 1,52 en la escala ponderada de indicadores utilizada, y que es necesario implementar estrategias que reduzcan la vulnerabilidad del cultivo de papa en cuanto a la conservación de la vida del suelo y manejo de la agrodiversidad . Mediante inoculación con la cepa Azotobacter sp. se obtuvieron diferencias significativas (P < 0,05) con respecto al control sin inoculación, aumentando el rendimiento de tubérculos y el peso comercial por hectárea, con un menor daño por mosca minadora (Liriomyza huidobrensis) frente al control. Se concluye que la utilización de bacterias promotoras del crecimiento en la papa puede ayudar a reducir la vulnerabilidad del cultivo, incrementando el nivel de sustentabilidad ambiental a nivel de finca. | ABSTRACT The potato is a crop originating in Peru with a wide genetic diversity and that currently grows in small farms in more than 300 thousand hectares in Peru, generating rural employment, being therefore a priority to evaluate the sustainability of production systems in accor-dance with agronomic practices that are environmentally friendly. A research was carried out to determine the effect of inoculation of native bacterial strains on the agronomic performance of potato farms in the Lima region, with agronomic trials being installed in field conditions under the complete blocks design and evaluating agronomic characteristics andproductive aspects of the crop. Previously, the degree of environmental sustainability of the potato farms in Lima region was determined through the Sarandon multicriteria analysis. It was determined that the potato farms at Lima region have a low level of environmental sustainability with a value of 1.52 in the weighted scale of indicators used and that it is necessary to implement strategies that reduce the vulnerability of potato farms in terms of conservation of soil life and management of agro-biodiversity. By inoculation with strain AZO16M2 (Azotobacter sp.) significant differences (P < 0.05) were obtained with respect to control without inoculation, increasing the tuber yield and the commercial weightper hectare, with less damage by leafminer fly (Liriomyza huidobrensis) compared to control. It is concluded that the use of growthpromoting bacteria in the potato farms can help to reduce the vulnerability of the crop, increasing the level of environmental sustainability at the farm level.

Sweet potato, often termed “the poor man's crop”, is an important root crop largely produced by resource-poor farmers in the tropical and subtropical regions of the world. It has been reported to be adapted to a wide range of environmental conditions. Recently, there have been efforts to promote orange-fleshed sweet potato to address vitamin A deficiency among poor rural people. The study investigated yield, water use, and water use efficiency (WUE) of three sweet potato cultivars (A40, A45 and 199062.1062.1) under different environments (Umbumbulu and Fountainhill in KwaZulu-Natal, South Africa) and agronomic practices (flat and peaked ridges). The experiment at each site was in split-plot design arranged in completely randomized blocks with three replications. Water use was calculated as a residual of the soil water balance. At harvest, yield was determined as below ground fresh biomass. Water use efficiency was obtained as the quotient of fresh yield and water use. Data from the two sites were analyzed separately as they were not homogenous. Higher yield was observed at Umbumbulu (13-35.5 t ha(‑1)) compared to Fountainhill (7.6-17.8 t ha(‑1)). At Fountainhill, A45 was the highest yielding cultivar under peaked ridges (17.8 t ha(‑1)). At Umbumbulu, A40 was the highest yielding cultivar under peaked ridges (35.5 t ha(‑1)). At both sites, flattened ridges used more water relative to peaked ridges. At both sites, WUE was higher under peaked ridges. Cultivars performed differently at each site and under the different ridge types. Flattened ridges favored neither high yield nor improved WUE. There is need to adopt different cultivars to improve yield and WUE across different environments.

Sound management of late blight, the disease caused by the notorious oomycete pathogen Phytophthora infestans (Mont.) de Bary, is dependent on the pathogen’s population biology. However, for P. infestans population structure to give guidance for disease management, successful information flow between the researchers and the practitioners is paramount. We analysed the population in eastern-Africa to determine the pathogen genotypes present in the region. We characterized the isolates using microsatellite markers and mitochondrial DNA haplotypes to enable comparisons with global populations. A European lineage, 2_A1 was found to be dominating the population in eastern-Africa. In addition, the 2_A1 lineage was found to be more aggressive in terms of lesion size, latent periods and incubation periods when compared to the old US-1 lineage. We thus concluded that the tested aggressiveness traits could have partly contributed to the quick displacement of US-1 by 2_A1 in the region. In a study predicting host durability of a genetically engineered potato with a stack of three resistance genes as well as a conventionally bred potato with a stack of five resistance genes, the assessment of pathogen effector genes proved valuable to deduce which of the R-genes were functional in the field. From the effector study, it can be concluded that effector genes in target local P. infestans populations should inform selection of breeding materials since globally, pathogen populations are very diverse. An assessment of commonly grown potato cultivars in eastern-Africa to quantify their susceptibility to late blight in the field found out that nearly all cultivars had partial resistance to P. infestans. The growers’ choice of cultivars is to high degree governed by market demands. Unfortunately, many cultivars with good resistance to late blight have other undesirable agronomic traits hence the rationale behind growing cultivars that are highly susceptible to late blight. Disease management practices, host durability prediction tools and potato breeding approaches should be suitably adjusted to the existing pathogen population.

A field experiment was conducted during rabi, 2017-18 in Assam Agricultural University, Jorhat to identify appropriate adaptive strategies for combating ill effect of heat and moisture stress through modifying microclimate in rice-potato double cropping system. The potato variety – Kufri Jyoti was planted in split plot design with 3 dates starting from 10 November at 10 days interval (main plots) and three mulching treatments with water hyacinth, black polythene and without mulching (sub-plots) following recommended agronomic practices. The study revealed that there were 11.8 and 7.0 per cent increase in average soil moisture content under water hyacinth and black polythene, respectively as compared to non-mulched treatment. On the other hand, soil temperature was 0.5 to 1.5 °C (morning) and 1.1 to 2.3°C (evening) lower under water hyacinth, but 1.2 to 2.1°C (morning) and 1.7 to 2.6 (evening) higher under black polythene as compared to non-mulched crop. In all planting dates, crop growth parameters like LAI and biomass production were observed to be highest under water hyacinth, followed by black polythene and without mulching. Among the mulching treatment the highest and lowest tuber yield was recorded under water hyacinth (120.81 q ha-1) and non-mulched treatment (85.0 q ha-1), respectively in all planting dates.It was found that the tuber yield was significantly and positively correlated (at 5% level) with the average soil moisture retention (mm) in upper 30 cm layer of soil during tuber formation to physiological maturity (r =77*). Increase in tuber yield (up to 42.2%) under water hyacintheven in case of late plantings (beyond 10 November) was probably due to increase insoil moisture retention (8.1 to 15.7 %) and reduction of soil temperature (1 to 1.8°C) under water hyacinthwhich endowed with favorable hydrothermal environment as compared to that under black polythene and non mulched treatment.

Seed systems for roots, tuber, and banana (RTB) crops receive relatively little attention from development-oriented research and commercial seed sector actors, despite their importance for food security, nutrition and rural livelihoods. We review RTB seed systems—with particular reference to potato, sweetpotato, cassava, yam and banana —to reflect on current seed system development approaches and the unique nature of these systems. We refer to our own experiences, literature and 13 case studies of RTB seed system interventions to identify gaps in our knowledge on farmer practices in sourcing and multiplying seed, and processes affecting seed quality. Currently, most approaches to developing RTB seed systems favour decentralised multiplication models to make quality seed available to smallholder farmers. Nevertheless, arguments and experiences show that in many situations, the economic sustainability of these models cannot be guaranteed, among others because the effective demand of farmers for seed from vegetatively propagated crops is unclear. Despite the understudied nature of farmers’ agronomic and social practices in relation to seed production and sourcing in RTB crops, there is sufficient evidence to show that local RTB seed systems are adaptive and dynamic. Our analysis suggests the paramount importance of understanding farmers’ effective demand for seed and how this affects the sustainable supply of quality seed from specialized producer-entrepreneurs, regardless of the seed system paradigm. From the case studies we learnt that few interventions are designed with a rigorous understanding of these issues; in particular, what types of interventions work for which actors, where, and why, although this is a necessary condition for prioritizing investments to increase the use of improved seed by smallholder farmers.

Water and nitrogen (N) use efficiency is an important focus in agricultural research. Moreover, the estimation of N-uptake efficiency of inorganic fertilizer application is a key aspect to develop best management practices (BMPs). The general objective of this study is to assess potato nitrogen and water use efficiencies for different inorganic nitrogen fertilization levels in the Peruvian Central Andes (Mantaro Valley). A further objective was to evaluate the seasonal change of potato biomass and N-uptake. During the 2015-2016 rainy cropping season, one experiment with different N fertilization (0, 100, 200, 300 and 400 kg N ha‑1) was established on a clay loam soil. Destructive measurements were periodically performed in order to calculate leaf area index (LAI), biomass and N-uptake dynamics. Actual total evapotranspiration was adjusted to LAI measurements reaching 343, 436, 426, 438 and 438 mm, not representing a limiting factor in relation to the water supply (462 mm). An improvement of aboveground biomass from 51.2 (100 kg N ha(‑1)) to 61.8 t ha(‑1) (400 kg N ha(‑1)) in relation to N fertilization was achieved. Fresh tuber yield (13.6, 41.9, 47.2, 55.0 and 52.3 t ha(‑1) was significantly enhanced by N fertilization, reaching optimal production with 200-300 kg N ha(‑1). Similarly, N treatments markedly improved N-agronomic efficiency (NAE; 31.9, 26.8, 24.2 and 21.9 kg kg(‑1)), N-apparent recovery efficiency (NARE; 50.5, 48.1, 55.1 and 50.7%) and N-harvest index (NHI; 72.9, 78.8, 71.7 and 73.8%). A not obvious increasing trend in function of the N treatments was obtained for NARE and NHI due to the combined effect of N-uptake, N-assimilation and N-losses. However, 200 and 300 kg N ha(‑1) represented the most efficient treatments for NARE and NHI, respectively. Water use efficiency was indirectly enhanced from 8.45 kg m‑3 (100 kg N ha(‑1)) to 15.28 kg m‑3 (400 kg N ha(‑1)). Future developments of soil-crop BMPs under rain-fed conditions should focus on optimizal time and dosing of N application under integrated approaches to enhance N-use efficiency indices under local conditions.

This paper describes the on-farm profitability and sustainability implications of smallholder dairy farmers in Pakistan from an innovative informal strategy of developing village-based forage seed enterprises (VBFSEs) for berseem clover (Trifolium alexandrinum). The evaluation of agricultural innovations and their impact on whole farm profitability is often very difficult to relate to economic parameters. The agricultural interventions implemented in this study resulted in enhanced crop yields, but the farmers involved did not consider these gains fulfilled their economic rationale. The impact of growing improved varieties of berseem clover using research based technology and developing VBFSEs was validated through on-farm participatory research in the districts of Kasur and Okara, Punjab, Pakistan. The intervention was evaluated on the basis of net income and benefit:cost ratio to the farmers on their investment. The statistical analysis indicated that average net incomes of 512,340 Rs/ha (5,240 US$/ha) was achievable through establishing VBFSE for berseem clover when grown for both green fodder and seed production. The maximum green forage (50.58 t/ha) and seed yields (946 kg/ha) of berseem clover were produced by using improved seed and contemporary agronomic practices compared to 31.76 t/ha and 192 kg/ha, respectively with traditional methods of growing berseem clover. The average net income generated through berseem VBFSEs is eight times greater than for wheat (34,022 Rs/ha), six times more than for oats (45,541), five times more than for canola (56,083), four times more than for conventional berseem clover (67,723), and two times more than the net income from a potato crop (142,737) growing in the region. Thus berseem clover VBFSEs are more profitable than any other cash crop grown in the area, having a benefit to cost ratio of 5.32:1. They are therefore an economically viable agricultural option for smallholder farmers.

The potato (Solanum tuberosum L.) is an important cash and food security crop in the eastern highlands of Ethiopia. However, the yield of the crop is constrained by low soil fertility and poor agronomic practices. Therefore, the field experiment was conducted at the main campus of Haramaya University and at Hirna Research substation during the 2015 main cropping season. The objective of the experiments was to elucidate the effect of seed tuber planting depth and nitrogen fertiliser rate on yield-related traits and yield of the crop. The treatments consisted of four seed tuber planting depths (5, 10, 15 and 20 cm) and five rates of nitrogen (0, 46, 92, 138 and 184 kg N ha⁻¹). The experiment was laid out as a randomised complete block design with three replications. The results of the experiment at both locations revealed that the main effect of nitrogen application rate influenced total dry weight, unmarketable tuber yield, the percentage of small-sized and medium-sized tubers. Nitrogen rate and seed tuber planting depth also interacted to influence unmarketable tuber yield, the percentage of medium and large-sized tubers produced, and tuber starch content. The main effects of seed tuber planting depth significantly influenced total dry biomass, unmarketable tuber yield, total tuber yield, marketable tuber yield, the percentage of small-sized tubers produced and tuber starch content. Increasing seed tuber planting depth generally enhanced the aforementioned parameters. However, for most parameters, the highest values were obtained already at the seed tuber planting depth of 10 cm. The optimum total and marketable tuber yields of 26.93 t ha⁻¹ and 26 t ha⁻¹ for Haramaya and 34.57 t ha⁻¹ and 32.65 t ha⁻¹ for Hirna were obtained in response to planting seed tubers at the depth of 10 cm.

It is estimated that about 7000 plant species and a large number of cultivars and varieties have been cultivated for consumption in human history. However, <0.5% of these currently provide the majority of human food energy needs worldwide (e.g., rice, wheat, maize, and potato). Global issues such as climate change, diffusion of pests, and resistance to agrochemical treatments are posing great concern about the sustainable cultivation of these major staples, especially in equatorial and tropical countries, such as Sub Saharan Africa. In addition, most of these regions contain malnutrition and micronutrient deficiencies, and the sum of such problems create serious implications at social, political, and economic levels. A possible solution relies on the exploitation of plant biodiversity and particularly on the so-called NUS (Neglected and Underutilized Species). These plants are traditionally grown in their centres of origin and continue to be maintained by sociocultural preferences, however they remain inadequately documented and neglected by formal research and conservation programs. Although they are important in terms of micronutrients and the ability to grow in harsh conditions, these species are falling into disuse due to agronomic, genetic, economic, and cultural reasons.To promote and spread their cultivation at the global scale, along with knowledge on their suitability for human nutrition, reliable identification systems are necessary to guarantee adequate authenticity along the entire supply chain and distribution network. A precise identification of the different species and their varieties is fundamental both to retrieve information on their origin and authenticate the raw materials (i.e., seeds, leaves and fruit) and related processed products that can be distributed at the local or global scale. DNA-based techniques can help achieve this mission. In particular, the DNA barcoding approach has gained a role of primary importance due to its universality and versatility. Here, we discuss the advantages in using DNA barcoding for the identification of some of the most representative NUS species, as well as their traceability and conservation of cultural practices around them.