Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Introduction. Traditional agricultural production systems prevail in the southern region of Nariño, however, the area harvested from transitory potato, corn and beans crops has been decreased. To address this problem, pea planting has been strengthened, which is marketed in local and regional markets. The department of Nariño is the first pea producer in Colombia, and in 2018, 9425 ha were reported, with an average yield of 1.19 t ha-1. The farmers in the study area are traditional and show technical limitations of production and commercialization. Objective. The objective of the investigation was to analyze the production and commercialization of peas in the department of Nariño. Materials and methods. The research was descriptive and allowed to establish costs, production volumes, planting times, product characteristics, prices, and marketing during 2012. The target population included producers, municipal intermediaries, wholesalers and retailers, and association leaders located in the pea-producing municipalities. Results. The Andean variety was the most sown, the post-harvest losses were 52 %, the prices vary due to the seasonality of production, and the greater volume of production was channeled through intermediaries. Conclusions. The production and commercialization of peas in Nariño presents difficulties that requiere sowing planning to balance production volumes, access development credit, train and organize farmers, and foster strategic alliances to guarantee conditions in the value chain. Keywords: productivity, competitiveness, value generation, production flow.

Introduction. The fruit and vegetable sector in Ecuador has shown promising performance in domestic and international markets. Likewise, this sector has faced problems of a social, economic and productive nature in its structure and articulations, which until now require intervention. Objective. The objective of this study was to analyze in a descriptive way the structure of the tree tomato agro-food network. Materials and methods. This study was carried out in the provinces of Cotopaxi, Tungurahua, and Chimborazo, Ecuador, during the period between the second quarter of 2016 and the end of 2017. The study applied a systemic methodology aimed at the identification and characterization of stages, agents and activities (primary and support), and the analysis of network governance mechanisms. Results. The present study showed the main social and productive characteristics, horizontal and vertical sizing; and the proposal of strategies focused on improving their productive performance. Conclusions. The inclusion of women, the sense of associativity of processors and distributors, and the training of producers in topics related to post-harvest, and good agricultural practices, would significantly improve the economic performance of the network, and also encourage greater participation of the agents involved. The network requires increasing the area allocated to tree tomato cultivation, and the application of greenhouse production systems that increase yields.

Introduction. Coffee (Coffea arabica L.) is an important crop in producing countries like Peru, where approximately two million families depend on its production, distribution, and marketing. But in recent years, climate change has increased the presence of coffee leaf rust - CLR (H. vastatrix), a disease that has decreased Peruvian production by up to 27%. Objective. Monitor the severity of CLR in different genotypes of coffee cv. Typica from April-2017 to March-2018. Material and methods. The experiment was carried out in the coffee germplasm bank at the Development Regional Institute (IRD)-Selva of the Universidad Nacional Agraria La Molina. The severity and the area under the disease progress curve (AUDPC) in the lower, middle, and upper part of coffee trees were quantified. Result. There was high severity and AUDPC in the dry season (low precipitation) compared to the rainy season (high precipitation). Severity and AUDPC gradually decreased from the bottom to the top of the plant (lower>middle>upper). Also, UNACAF-24A, UNACAF-16, UNACAF-158, and UNACAF-162 genotypes stood out by showing lowest severity (0-1.1 %) and AUDPC (0-714) in the experiment. Conclusion. In this experiment, the genotypes in dry season presented high peaks of severity and UDPC of CLR, meanwhile, in rainy season the presence of CLR was lower. However, in both seasons, severity and AUDPC gradually decreased from the lower third to the upper thirf of the plant. Finally, UNACAF-24A, UNACAF-16, UNACAF-158, and UNACAF-162 presented the lowest degrees of severity of CLR.

Introduction. Efforts have been made in Colombia to increase the use of certified seed. However, the lack of knowledge among producers about its advantages, the absence of a stable supply and the dependence on commercial potato prices, limit the sustainability of its production. Objective. To evaluate financially and biophysically the production of seed potatoes in the department of Nariño, Colombia. Materials and methods. The use, evolution, adoption, and costs of potato seed were evaluated between May 2016 and April 2018, to consolidate bases that allow creating sustainable production models. This information was collected through surveys to 1018 producing households in twenty-one local municipalities. To define the biophysical parameters, a semi-structured interview was used to extract ranges and aptitudes in cartographic layers, which were framed in an area with rainfall between 800 to 1600 mm year-1, loamy soils with slopes of 15 %, altitude between 2800 to 3200 m.a.s.l. and temperature of 8 to 15 ° C. The agribusiness behavior was established with a seven-year projection of production costs, based on a review of primary sources and figures of areas sown during the last ten semesters, which was compared with the estimate of the percentage of current seed use in the region to establish the potential demand. Results. The economic burden did not allow generating significant yields in a single hectare (: 6 %), because they were lower than the commercial potato production (: 18 %), with an average of 20 % and internal rate of return (IRR) of 28 %. Conclusion. The minimum area to overcome the profitability of commercial potato production was three hectares, managing to supply 3 % of the seed demand. The areas with greatest potential for production were the municipalities of Pasto, Tangua, and Sapuyes.

Introduction. Beef production is affected by stationarity forage production and fed cost. Feed frequency evaluations according to pasture could suggest an appropriate practice for profitability improvement. Objective. To evaluate technically and economically the frequency of supplementation of Brahman fattening steers in grazing. Materials and methods. In the middle valley of the Sinú river, Colombia, 108 steers were used distributed in a split-plot design into three pastures (Cynodon nlemfuensis, Megathyrsus maximus, and Brachiaria hybrida, main plot) and three supplementation schemes (subplot): daily (STD), every two days (SDpM) and without supplementation (SS). The daily weight gain (GPD) and morphometric characteristics were evaluated in steers. In the carcass: weight, yield, length, leg perimeter, fat thickness, and compactness index. The biophysical data results fed the financial evaluation of the implemented technology. Results. An interaction of pasture and supplementation frequency over daily weight gain was detected (p<0.05). The highest GPD was observed in animals of the STD treatment for the grass C. nlemfuensis (680 g day-1), while a B. hybrida cv Mulato II in SDpM recorded the lowest GPD with 500 g day-1. An effect (p<0.05) of the diet on body length was observed (150 vs. 152 cm for not supplemented and supplemented steers, respectively). There were no differences (p<0.05) between treatments over carcass characteristics. Conclusions. The biological response in GPD did not compensate for the differential operating cost in the supplemented animals. It is necessary to evaluate new diets with raw materials and inclusion levels that contribute to the increase in animal production, to generate a detectable change in the animal and economic response.

Introduction. During decades, milk production in the Nariño state has depended on the Holstein breed. For this reason, it is necessary to evaluate a model of milk production that allows to decrease production costs and in turn improves the compositional quality of the milk. Objective. This study aimed to compare milk production and compositional quality of Holstein (HO) and the crossbreed between Kiwi Cross (KC) x HO. Materials and methods: Monthly milk production in HO cows (n=30) and the ones from the F1 of the KC x HO cross (n=40), was measured by adjusting the day in milk (DIM) and milk production by third of lactation, fat, protein and total solids. For the period between October 2016 and May 2017, 9,809 dairy production records were analyzed. Results: Maximum production was 25.8 ± 0.53 vs. 23.2 ± 0.53 l day-1 for HO vs. KC cows (p<0.05), respectively. The DIM was not different; however, in days 60, 90, 150, 180, 210 and 240 the HO group produced more milk than the KC group, with a persistence in the lactation peak until day 60, and from that point onwards milk production showed decreasing rates in both groups. Furthermore, the production per third of lactation was higher (p<0.05) in the first third compared to the second and third periods for HO (13.6±0.56 vs. 11.3±0.5723 and 9.9±0.47 l day-1, respectively) and KC (12.8±0.4505 vs. 10.6±0.66 and 9.5 ± 1.69 l day-1, respectively). Fat content was higher (p<0.05) in KC compared to HO in week one, three and five (4±0.07, 4±0.07, 4±0.07 vs. 3.6±0.12, 3.6±0.11, 3.7±0.09 %, respectively); likewise, protein in week one and four was higher in the KC group compared to HO (3.3±0.04 vs. 3.1±0.05 %; p<0.05). Total solids were 13.3±0.17 vs. 12.5±0.23% (p<0.05) for KC and HO cows, respectively in weeks two and five. Conclusion: Milk production in KC and HO was similar; however, KC improved performance in compositional milk quality, increasing the percentages of fat, protein and consequently, total solids.

Introduction. Traditional livestock production systems in Colombia are based on the establishment of pastures on large tracts of land, which generate greenhouse gases such as methane. Objective. The objective of the present study was to monitor the monthly methane fluxes that occur in meadows with three soil covers and three levels of nitrogen fertilization. Materials and methods. Methane fluxes were monitored for a year from November 2014 to November 2015, on a Vertic Endoaquepts soil, placed in the middle valley of the Sinu river, Colombia. A full block design was used at random, arranged in divided plots, with two replications. The main plots constituted of two grasses (Brachiaria humidicola CIAT679 and Panicum maximum cv. Tanzania) and one with bare soil, and the subplots by three nitrogen fertilization levels (0, 150, 300 kg N ha-1). Additionally, soil physicochemical properties were evaluated. Results. During most of the year (rainy and dry season) methane oxidation occurred, associated with the loam texture and porosity of the soil in the study area, which allowed the free diffusion of gases in the soil. Correlation analyzes showed a close relationship between methane fluxes, porosity, moisture, soil bulk density, and ambient temperature, suggesting these parameters as the main factors that affect the monthly methane flow. Conclusions. Methane fluxes were independent of the type of plant material and nitrogen fertilization evaluated. These flows depended on the time of year (dry and rainy) and exhibited a negative annual balance in the study area, which suggests that these systems have the conditions to behave as methane sinks during most of the year. 

Introduction. The energy content of forages is a limitation for milk production in grazing systems, and the net energy of lactation is the parameter most used to express the energy requirements of dairy cattle. Objective. To compare the net energy of lactation in feeds, obtained from equations based on in vitro gas production, with that estimated by the National Research Council (NRC) model. Materials and methods. The experiment was carried out from August to December 2017 at the Animal Nutrition Research Center of the Universidad de Costa Rica, San Jose, Costa Rica. In vitro gas production was determined in samples of star grass, ryegrass, corn silage, mulberry, and concentrate. Five equations that incorporated accumulated gas production at 24 hours were evaluated. Results. Gas production showed differences (p<0.001) between feeds. The highest volume of gas produced and content of net lactation energy (NEL) was obtained with concentrate. Equation 3 showed de highest precision for the estimation of NEL, which also reached the highest concordance correlation index (r2=0.92). The use of equations by type of feed improved the accuracy for the NEL prediction. Equation 1 was more precise in concentrate while in corn silage it was equation 4, and in mulberry, star grass and ryegrass it was equation 3. Lin’s concordance index explained the differences in prediction of NEL1x better than the Pearson correlation index. Conclusion. The in vitro gas production technique with the application of equation 3 was a reliable method to estimate the NEL1x content in five feeds used in dairy cows

Introduction. The germination of Ischaemum rugosum Salisb. is uneven due to the presence of latency, a process that affects its management and research. Objective. To evaluate three methods for breaking dormancy in I. rugosum Salisb. seeds that allow its uniform germination under controlled conditions. Materials and methods. Three experiments were carried out at the Laboratorio Oficial de Análisis de Calidad de Semillas del Centro para Investigaciones en Granos y Semillas of the Universidad de Costa Rica, San José, Costa Rica; from May to June 2016. In the first experiment, potassium nitrate and distilled water, two imbibition times, and a control without imbibition were tested. In the second, the seeds were subjected for three weeks to four constant temperature regimes (15 °C, 30 °C, alternating temperatures 15 and 30 °C, and ambient temperature of 26 °C). In the third, seeds were placed in water for one hour at different degrees of heat (23, 30, 45, and 65 °C), a control without imbibition was used. Results. In the first experiment, the best treatments were 16 and 24 h of imbibition with potassium nitrate. In the second experiment temperature was a significant factor, germination was reached with three temperatures used, only with 15 °C there was no germination. In the third experiment the temperature in the water was a significant factor, the highest germination occurred in the treatment at 23 °C, while at 65 °C no germination occurred. Conclusion. The use of hot water as a way to break latency was ruled out. It is concluded that the best treatments were KNO3 at 0.25 % for 16 or 24 h, while the use of water was only effective in the time of 16 h, in all three cases alternating temperatures between 15 and 30 ° C.

Introduction. The cattle borer worm, Cochliomyia hominivorax (Coquerel), is an economically important pest for warm-blooded animals, mainly cattle. Objective. Molecularly characterize six strains of Cochliomyia hominivorax (Coquerel) and the Cochliomyia macellaria species using the mtDNA sequences. Materials and methods. The study was conducted during 2006 and 2007, using six strains from colonies of Mexico, Panama, and Costa Rica, located in the Molecular Biology Laboratory of the Smithsonian Tropical Research Institute, Panama. Three out of six primers were optimized and evaluated, using the cyclic sequencing method. Parsimonia, NJ (Neighbor-Joining), Maximum Likelihood, and Bayesian analyzes were performed to establish the phylogenetic relationships between the strains. Three primers used for C. hominivorax were evaluated for C. macellaria. Results. The regions of the mitochondrial genome NADH4-tRNA-NADH5 were obtained. All the analyzes showed the same topology forming four defined clades. The first formed by the strains from Oaxaca and Quintana Roo, the second by the strains from Chiapas, the third by the strains from Costa Rica and Panama, and the fourth by the population from Brazil, obtained from GenBank. In C. macellaria two primers were able to amplify the NADH4 region and one NADH5 region. Conclusion. The amplifications obtained in this research provide information to continue the molecular studies between the species of C. macellaria and C. hominivorax; also to identify the geographical origin of the strains.