Agronomía Mesoamericana

Dynamics of severity of coffee leaf rust (Hemileia vastatrix) on Coffee, in Chanchamayo (Junin-Peru)

Tue, 01 Sep 2020 00:00:00 -0600

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.

Morphological, morphometric and molecular identification of Meloidogyne exigua (Göeldi 1887) in coffee (Coffea arabica)

Roy Artavia-Carmona, Walter Peraza-Padilla — Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The genus Meloidogyne contains many species and their correct diagnosis of these must be based on the use of multiple tools, which in diagnostic laboratories allow a correct and reliable evaluation, specially for quarantine nematodes. The proper identification of a phytonematode is important not only to establish an appropriate control strategy, but also to avoid its spread to other areas where it could cause damage that would result in economic losses. Objective. To perform taxonomic and molecular studies to confirm the Meloidogyne species, associated to a coffee plantation located in Barva, Heredia. Materials and methods. Soil and root samples were collected in a coffee plantation located in Barva, Heredia, Costa Rica, which were processed in the Nematology laboratory of the School of Agricultural Sciences at the Universidad Nacional (UNA), using the centrifugation-flotation method in sugary solution and molecular techniques. Results. On average, 30 J2 100 cc-1 were counted in soil and 1000 J2 10 g-1 of roots of the root-knot nematode. Taxonomic and molecular techniques allowed to identify that the females and juveniles extracted from coffee roots corresponded to Meloidogyne exigua. Analysis of the sequences generated by PCR and the use of the DraI enzyme confirmed the identity of the species with 99 % similarity when compared to sequences from Costa Rica and Nicaragua, reported in the Genbank. Conclusion. Using different morphometric and molecular techniques, M. exigua associated with a coffee plantation was identified.

Effect of the organic and mineral fertilizer on the performance of sugarcane yield in Nariño, Colombia

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. Colombia is the second producer of panela or non-centrifugal sugar (NCS) in the world, after India. In 2016, the department of Nariño had an area in sugarcane (Saccharum officinarum L.) for harvested sugarcane or NCS of 10 533 ha and an average yield of 7.67 t ha-1 for 6.35 % of total production of panela or NCS in the country. Objective. To evaluate the use of organic and mineral fertilizer on the sugarcane yield for panela or NCS production in its first production cycle. Materials and methods. The study was carried out between the months of November 2008 to March 2010 in the village of Villa Ines, Consaca, Nariño; a randomized complete block design was used, considering continuous sowing systems (SEC) and spacing (SE) ajusted NPK levels according to soil analysis, with chemical (FQ) and organic (FO) sources. The yield was evaluated in cane and panela or NCS, and reducing sugars and phosphates. Results. The treatments (T3) SEC-FQ with 168.20 TCH, (T1) SEC-FA with 167.07 TCH and (T5) SE-AO with 167 TCH showed the highest cane yield compared to the other treatments, and where significantly different from the control treatment (T9). In panela or NCS, the best treatment was (T6) SE-FQ (12.1 % conversion and 18.78 t ha-1). The highest value of reducing sugars was (T8) SE-FA with 13.2 % while in phosphates it was (T9) SEC and SE-SF (753 ppm), and SEC-AO (706 ppm). With 1,500 kg ha-1 of commercial organic fertilizer, cane yields above 100 t ha-1 and panela yields or NCSof 15 and 17 t ha-1 in SEC and SE, respectively, were obtained, similar to those achieved with chemical fertilization. In chemical fertilization, with the mixture of sources the use of nitrogen was reduced by 42 % and phosphorus by 18 %, with cane yields 44 % higher than the regional average and panela yields 20 % higher than the control. Conclusion. It was possible to reduce and supply some nutrients of chemically synthesized nutrients without affecting the sugarcane and panela or NCS yields.

Chemical and organic fertilization in oats: seed yield and quality

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. Oatmeal (Avena sativa L.) has its origin in Central Asia and is an important crop in Mexico, where there are high grain yields, besides as being an alternative for producers who sow in temporary. Objective. To evaluate the effect of chemical and organic fertilization on the yield and physiological quality of the seed of three oats varieties, during two agricultural cycles (years). Materials and methods. The experiment was established during the autumn-winter cycle at the Tecnologico Nacional de Mexico campus Roque, Guanajuato, Mexico. Two sowing dates were established in 2015 and 2016, considered as factor A. The varieties of the experiment were Turquoise, Diamond, and Chihuahua, assigned as factor B and five fertilizations based on vermicompost and chemical nutrition as factor C, sowed in three replications. Seed physiological quality variables and seed yield components were measured. Characteristics were analyzed in a randomized complete block design with factorial arrangement and a Tukey 0.05 mean comparison test. Results. The environmental effect influenced the seed quality, agronomic characteristics, and grain yield. In the 2016/17 cycle there was a 14.41 % increase in seed yield compared to the 2015/16 cycle. The three oats varieties maintained the same behavior pattern, statistically the same for germination, days to seedling (appearance of the flower knot on the stem), days to flowering, number of seeds per spike, weight of 1000 seeds and seed yield. Oat yield and other physiological quality characters were similar with vermicompost (6.38 t ha-1) and chemical fertilization (6.46 t ha-1). Conclusion. A similar response was found in yield, weight of 1000 seeds, and physiological seed quality, with both types of fertilization.

Altoandina: new variety of forage oats for the Andean area in Colombia

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The evaluation and selection of new fodder species with appropriate production and quality attributes is a safe and effective strategy to improve the efficiency of milk production systems in Colombia. Objective. To describe the development process and the main characteristics of Altoandina, a new variety of fodder oats. Materials and methods. During the second half of 2016, an agronomic assessment test (PEA) was carried out in four locations in the Altiplano Cundiboyacense subregion and in four locations in the Altiplano of Nariño subregion, in a randomized complete block design, with two genotypes of fodder oats AV25-S and AV25-T and three varieties (Avenar, Cajica, Cayuse). Results. AV25-S and AV25-T showed: tolerance to overturn unlike the three controls that showed a overturn of more than 30%, resistance to leaf and stem rust, and green forage performance of 64.6 and 65.3 t ha-1, respectively, higher than that obtained in Avenar (55.5), Cajica (43.7) and Cayuse (59.1). Conclusion. AV25-T for its tolerance to overturning, resistance to leaf and stem rust and green fodder yield superior to commercial varieties, was registered in the national cultivar system as a new fodder variety called Altoandina, with recommendation for the Cundiboyacense Altiplano and Nariño Altiplano.

Trichoderma growth in pineapple stubble to obtain spores for agricultural use

María Catalina Vega Rodríguez, Rodolfo Antonio Hernández-Chaverri — Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The use of biological controllers as alternatives to traditional chemicals is an ecological and economic option for farmers. Fungi of the genus Trichoderma can confer resistance to plants and increase the absorption of nutrients, reducing a wide variety of crop diseases. Objective. To evaluate pineapple stubble wastes as a substrate for the solid fermentation growth of two Trichoderma strains to produce a spore solution for agricultural purposes. Materials and methods. The experiment was carried out at the Laboratory of Research in Chemistry and Applied Biosciences of the Universidad Tecnica Nacional of Costa Rica, in the period between April 2018 and October 2019. Two variants of fungus T. viride and T. harzianum were used, these were grown in natural potato dextrose agar (PDA) and pineapple stubble. A conidia count was performed in a 1/10 mm Neubauer chamber. Results. T. viride and T. harzianum showed uniform growth in reseeding plates with color changes in time, from white to green. T. viride showed better development in wet substrate, while T. harzianum in low moisture stubble. The maximum cell concentration in the liquid solution of T. harzianum and T. viride was 1 132 750 cell ml-1 and 1 023 250 cell ml-1, respectively. Conclusion. Both strains of Trichoderma developed adequately in the pineapple stubble, however, the efficient growth of the strains is associated with the management of external factors such as the amount of substrate, oxygen, and moisture.

Food attractants in McPhail traps to capture of pineapple fly (Diptera: Richardiidae)

Alfonso Villalobos-Moreno, Jesús Emilio Luke-Z, Jorge Villamizar-Cobos — Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The pineapple fly (Melanoloma viatrix Hendel, 1911) was first reported in Colombia in 1991, and has become a limiting pest in pineapple crops in this country. The information about the species is scarce and it is required to estimate its distribution, fluctuation, and density, in order to design integrated pest management strategies. Objective. To evaluate food attractants as a sampling mechanism of Melanoloma viatrix Hendel. Materials and methods. The tests were carried out in pineapples farms in the municipality of Giron, Santander, Colombia, during the beginning of the first rainy season of 2003. Eight food attractants were evaluated within McPhail traps located in six random blocks within three commercial pineapple crops of the Perolera variety. Results. The McPhail trap food attractant tests captured more than 13 000 individuals, including diptera, lepidoptera, hymenoptera, neuroptera, hemiptera, and orthoptera, but only 138 specimens of the study species. Conclusion. Significant differences were observed in the captures of M. viatrix, being pineapple rind pieces, pineapple rind extract and natural pineapple juice the attractants that presented the best capture results.

Improving strategic management through risk analysis: small palm (Elaeis guineensis) oil industrializers, Central America

Javier Paniagua-Molina, Johanna Solórzano-Thompson — Tue, 01 Sep 2020 00:00:00 -0600

Introduction. Palm cultivation allows oil to be obtained for human and industrial consumption. Some of its development has been achieved through associations of agricultural producers, who have had access to financing to build industrial plants for oil extraction and refinement, which is of great importance to the economy developing countries. Objective. To demonstrate how strategic and risk management influence the profitability and value of the small palm oil industrializer business. Materials and methods. Financial, technical, market, and production indicators were used in a price forecast model. The Monte Carlo simulation method was performed and a time series model was fitted to forecast the international price of palm oil. Subsequently, a univariate structural econometric model was adjusted to forecast revenue based on international price and other variables. Finally, a parameterized cash flow was developed that incorporated the results of the previous models to estimate the value of the business. Results. The international oil price forecast showed high volatility that directly affected the organization’s revenue forecasts and conveyed its effect to cash flows. The value of the business and equity was negative, and in the face of debt restructuring scenarios and the elimination of unproductive assets, they improved considerably. Conclusion. Low-diversified palm oil production companies had a high exposure to changes in international prices which, together with high levels of debt for fixed asset investments with long recovery periods, affect their cash flow, the value of the company, and its assets.

Financial and biophysical analysis for the potato seed production

Tue, 01 Sep 2020 00:00:00 -0600

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.

Economic risk in the production of Angus and Hereford beef in La Posta, Chihuahua, Mexico

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. Risk preference is the situation in which an agricultural producer decides to invest money and there is a probability of obtaining benefits from those desired. Objective. To evaluate risk preference and utility of intensive Angus and Hereford beef production in Rancho Teseachic, La Posta, Chihuahua, Mexico through monetary utility. Materials and methods. The experiment was conducted from March 24th to August 11th 2017. 52 cattle were evaluated and fed for a period of 141 days with rolled corn (53,3 %) and distillers’ grain (37,8 %). The animals were divided into two lots: one with 32 Angus heads with 226.28±28.69 kg of initial live weight and the other with 20 Hereford heads with 191.58±24.23 kg of initial live weight. An econometric model was adjusted, using Ordinary Minimums Squares, to determine the absolute and relative risk preference of the monetary utility in cattle fattening. Results. At the end of the period, the weight was 371.7±43.96 kg for Angus and 320.9±37.99 for Hereford. The production model indicated an optimum live weight at slaughter of 375.5 kg for Angus and 321.5 kg for Hereford. Conclusion. The producer rejected the risk-free preference to the risky preference. Meat production with Angus calves showed a lower risk preference (20 %) than Hereford calves (44 %) and therefore less utility.

Analysis of the competitiveness on pig farming in Tejupilco and Luvianos, Mexico (2006-2018)

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. Meat pork production is rank third of all meats in Mexico after beef and broilers. Production is not enough to supply the national consumption and reduce imports. Objective. Analyze the evolution of costs, profitability and competitiveness of pig production in the regions of Tejupilco and Luvianos, located in the South of the State of Mexico. Materials and methods. The investigation was carried out using information from forty backyard and one technificated farms; A Policy Analysis Matrix was used. Matrices were elaborated of technical coefficients, prices of inputs and product and private budgets. Results. Private returns (RP) were at 26% for backyard ones and 43% for technifhicated one, while private cost ratio (RCP) was 0.35 for backyard ones and 0.17 for technical one, thus, greater competitiveness was observed in the latter. Conclusion. Indicators point out these two types of pig farms were profitable in 2018, and were competitives in relation to those obtained in 2006, it was mainly due to movements in constant terms of inputs costs, which decreased and the increase in the price of live pigs, which contributed producers taking actions to be more productive and efficient.

Characterization of the Zebu cattle population with a certificate of genealogical registration in Costa Rica

Marilyn Vásquez-Loaiza, Roger Molina-Coto — Tue, 01 Sep 2020 00:00:00 -0600

Introduction. There is not much information on pure cattle with a genealogical certificate in Costa Rica. It is necessary to know the status of this population to direct efforts towards the productive improvement of the Zebu cattle breeds. Objective. To update the database of the Costa Rican Cebu Cattle Breeders Association (ASOCEBÚ), characterize this population and analyze the use of males of the gray Brahman breed in the country. Materials and methods. An inventory was done in 121 herds to update the Association’s database to 2018. The information was sorted by breed, sex, age, total animals, breeders, socio-economic region, province, and canton. The frequency of use of gray Brahman breeders was determined. Results. A total of 10 995 pure animals were counted, distributed in six breeds (gray Brahman, red Brahman, Nelore, Gyr, Guzerat, and Indubrasil). The gray Brahman breed predominated with 74.5 % of the population and 76.8 % of the total of breeders. The Chorotega region had the highest registered population (49.5 %) and the highest number of breeders (37.2 %). 55.8 % of the total population came from ten breeders, however, the largest number of herds corresponds to farms with few animals. In the gray Brahman breed, 60.8 % of the population comes from domestic bulls, and 39.2 % from other countries. Conclusion. Registered pure zebu cattle are distributed throughout the whole country. Attention should be put to genetic management to minimize inbreeding. Census and survey managers are encouraged to include the purebred populations in their assessments.

Quality of raw milk in the highland tropics of Nariño, Colombia

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The production and commercialization of raw milk in Nariño, Colombia, follows microbiological and compositional standards on which payment for quality is made. However, quality can be affected during its transport after milking. Objective. To describe the microbiological and compositional quality of raw milk in the highland tropic. Materials and methods. The study was carried out in seven municipalities in the department of Nariño, Colombia, during the rainy season between February and July of 2017. Two milk samples from the same milk can were collected, one after milking (farm; n = 10), and the second at the collection point (tank; n = 10). In each sample, the following variables were evaluated: height above the sea level of the collection site, aerobic mesophilic count (CFU), total coliform count (COL), milk temperature, fat (FAT), protein (PC) and total solids (TS). Results. The temperature of the milk was higher on the farm compared to the tank (30±0.68 vs. 23±0.87 °C, respectively). The aerobic mesophilic count was higher in the tank vs. farm (116,470 vs. 41,388 CFU ml-1, respectively). The temperature of the milk was negatively correlated with the distance and the transport time of the milk (-0.86 and -0.84, respectively). The compositional quality of the milk was not affected by transport conditions. Conclusion. In the high tropic conditions, the microbiological quality of raw milk was negatively affected by the increase in the aerobic mesophilic counts.

Natural ventilation in greenhouse with anti-insect screens evaluated with a computational fluid model

Edwin Andrés Villagran, Jorge Eliecer Jaramillo, Rommel Igor León-Pacheco — Tue, 01 Sep 2020 00:00:00 -0600

Introduction. In Colombia, horticultural production in the low tropics is limited mainly by biotic factors such as pest attacks, pathogens, and abiotic factors such as extreme values of temperature, solar radiation, wind, and precipitation. Objective. To evaluate two types of anti-insect screens in the ventilation areas of a naturally ventilated Colombian greenhouse in order to analyze the effect on the ventilation rates and the generated microclimate. Materials and methods. The study was carried out in 2019 in the department of Magdalena, Colombia. The methodological approach included the use of a 2-D computational fluid model (CFD) for the development of fifteen steady-state simulations. The CFD model was experimentally validated in the prototype of the real greenhouse evaluated. Results. Goodness-of-fit parameters between measured and simulated data showed absolute mean error (MAE) and root mean squared error (RMSE) values for temperature and relative humidity of 0.15 and 0.32 °C, 2.41 and 2.73 %, respectively. There was an average reduction in ventilation rates between 55.3 and 77.1 % compared to the reference scenario that did not include the presence of anti-insect screens, this reduction generated modifications in the behavior of the temperature and relative humidity variables inside the greenhouse, with a marked heterogeneous spatial distribution. Conclusion. The most inadequate microclimatic conditions occurred in scenarios of low external wind speed; therefore, it is recommended to select and implement some type of anti-insect screen in the ventilation areas of a greenhouse based on the local behavior of this variable.

Phenotypic characterization of three Venezuelan sweet pepper (Capsicum chinense Jacq.)

Hernán Laurentin, Maryleidi Quevedo — Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The cultivated species of the genus Capsicum, among them C. chinense, are known for the pungency of their fruits, however, there are several types of this pepper that do not present pungency. Venezuelan cuisine is defined by the characteristic flavor of a class of peppers that do not present pugency, which are called sweet peppers. Among these, the best known and most used are the cultivars Rosita, Pepon, and Llanero. Objective. To characterize the Rosita, Pepon, and Llanero chilli pepper cultivar by means of 53 morphological characteristics and to determine the phenetic relationship among them. Material and methods. In a randomized block design with three treatments (cultivars) and five repetitions, 45 seedlings of each cultivar were arranged in La Vigia, Jimenez municipality of Lara state, Venezuela, in August 2017. The transplant was carried out in separate rows at 0.50 m, and the seedlings were spaced 0.50 m apart on the row. On the three plants of the central row of each experimental unit (fifteen plants in total for each cultivar) the category or value of attributes of stem, leaf, flower, fruit, and seed were determined. Results. Forty-two percent of these attributes were variable among the plants evaluated, fifteen of them were categorical and seven quantitative, and significant differences (p<0.05) were detected among cultivars. Flower and seed characteristics showed no variation among cultivars, while stem and fruits showed the greatest variation. As a whole, the morphological characteristics that presented variation allowed to identify each one of the cultivars and therefore, to discriminate them. Conclusion. The variation identified in the characteristics of the fruit is indicative of the potential for genetic improvement of the Venezuelan sweet pepper in its commercial part.

Physical soil fertility in the sowing system in wachado on Nariño, Colombia

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. In the wachado system, the soil used is continuously rotated with potatoes (one or two harvests) and pasture for dairy cattle (two to three years). Wachado is a pre-Columbian production system that only uses a manual tool, and is practiced and conserved by indigenous communities on Andean slopes of Colombia, Peru, and Ecuador. The system is relegated by the intensive mechanization systems in which research predominates, unlike the wachado research where it is scarce. Objective. To evaluate the effect of sowing in wachado on the state of some physical properties of the soil. Materials and methods. The work was carried out in three locations in the department of Nariño, Colombia, between January and March 2015. In each locality, soil samples were taken at different depths, and rain simulations were performed in triplicate to determine volumetric, water regulation, structural stability, and texture indicators in plots that were on pasture for three years. Results. After thirty years of use, the wachado soil retained a low apparent density (0.41 to 0.91 g cc-1), high total porosity (56 % to 70 %), high moisture content at low, and high suctions (75 % and 40 %). In addition, moderate structural stability (DPM greater than 1.5), 60 % microporosity, low infiltration (19 % to 33 %), and high runoff (66 % to 81 %) were found. Conclusion. After thirty years of potato cultivation under the wachado system, the values of the physical indicators of the soils showed that the minimum tillage and the potato/grass rotation, reduced soil degradation and regulated the hydric condition.

Macronutrient content and distribution in rambutan on the atlantic coast of Honduras

Breno Augusto Sosa-Rodrigues, Yuly Samanta García-Vivas — Tue, 01 Sep 2020 00:00:00 -0600

Introduction. Rambutan productivity depends on satisfying its nutritional demand through the use of fertilizers. Knowing the quantity and the times of greatest demand for nutrients by the plant allows the producer to improve fertilization programs. Objective. To evaluate the content and distribution of macronutrients in different ages of the rambutan crop. Materials and methods. An experiment was established in the Atlantic coast of Honduras under a completely randomized design with six treatments (sampling at 2, 3, 4, 8, 10, and 17 years of establishment) and three repetitions. The study was carried out between the months of March and December 2017. At harvest time, leaves, branches, shells, and seeds were collected to analyze the concentrations of N, P, K, Ca, Mg, and S in each one. Results. It was recorded that the macronutrient concentration differed significantly among the organs and ages of the plant, finding the highest concentration of N, Ca, Mg, and S in leaves, P in seed and K in the shell. The total concentration (leaf + branch + shell + seed) of the nutrients registered fluctuations over time and increased the demand for P, K, Ca, and Mg in years 2 and 3, to then decline in years 8 and 10. While the demand for N and S were constant during the development stages. In addition, N (41 %) was required in greater quantities, followed by K (24 %) and Ca (20 %) and finally P (6 %), Mg (5 %) and S (4 %). Conclusion. The content and distribution of macronutrients were variable according to the age of the plant, allowing the identification of which nutrients and when they were most required and the plant organ where it was accumulated.

Preemergence activity in the greenhouse on Arthraxon quartinianus, of an extract from Pinus sp.

Mary Pamela Portuguez-García, Renán Agüero-Alvarado, María Isabel González-Lutz — Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The pine extract may have herbicidal activity to other plants, affecting seed emergence. Objective. To evaluate the pre-emergent effect of a Pinus sp. extract in a greenhouse. Materials and methods. Two experiments were carried out in the K greenhouse of the Fabio Baudrit Moreno Agricultural Experimental Station (EEAFBM), Universidad de Costa Rica, the first in July and the second between September and October 2018. In the first one, the pre-emergent effect of pine extract, with and without added adherent to the spraying broth, on Arthraxon quartinianus (A. Rich.) and a seed bank containing different species were evaluated; in the second experiment the pre-emergent effect of pine on Amaranthus sp., Ischaemum rugosum Salisb., rice (Oryza sativa), cucumber (Cucumis sativus), and a seed bank was evaluated. For both experiments, a 15 % formulation of pine extract (3.75 kg a.i. ha-1) was sprayed. In both experiments, the number of seedlings emerged was counted, in the first experiment it was recorded at nine days after spraying (das) and in the second at 17 das. Results. The pre-emergent effect on broad-leaved species was not significant, but it was for A. quartinianus (A. Rich.) (p=0,0009). The adherent reduced the effect of the pine extract on A. quartinianus (A. Rich.) (p=0,0116) and other species (p=0,0398). There was an increase in the germination of weeds coming from the seed bank, 121 % for broad-leaved species in general, 92 % for Amaranthus sp. (p=0,013). Besides, the adherent increased the germination of rice seeds by 34 % (p<0,0001). Conclusions. In a greenhouse there was only a significant pre-emergent effect of pine for the weed A. quartinianus (A. Rich.). The pine extract increased the germination of several species.

Influence of shade and scarification on the germination of Ischaemum rugosum Salisb.

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The percentage of shade and scarification can influence the germination of Ischaemun rugosum Salisb. Knowledge of these aspects would allow establishment of successful measures for an integrated management of this species. Objective. To compare the influence of different percentages of shade on the germination of scarified and not scarified I. rugosum Salisb. Materials and methods. This experiment was carried out in micro-tunnels during the dry season and the transition to the rainy season, at Fabio Baudrit Moreno Agricultural Experimental Station, Alajuela, Costa Rica, during 2016. In the dry season, the following shade percentages were used 0 %, 30 %, 50 % (green saran), and 100 % (black saran). In the transition to the rainy season, the same percentages of shade were used, but the black saran was changed to 70 % white saran, in both experiments scarified and non-scarified seeds of the weed were used and germination was counted. The data were analyzed with logistic regression and a hypothesis test for the regression coefficients with a significance level of 5 %. Results. In the dry season there was greater germination with non-scarified seeds and 50 % shade. During the transition to the rainy season the highest germination occurred at four days after sowing (dds), under 50 % shade and with scarified seed, and fifteen days after sowing the highest germination (odds ratio 8.67 to 1) occurred with 70 % shade, green saran and scarified seed. Conclusion. Scarification allowed an increase in germination in the transition to the rainy season, not in the dry season. In both seasons there was a positive influence on germination with the shade percentages of 50 % and 70 %.

Imbibition and temperature to rupture latency of Ischaemum rugosum Salisb

Tue, 01 Sep 2020 00:00:00 -0600

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.

Feeding: a strategic factor for artificial rearing of calves from dairy farms

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The specialized dairy systems in Colombia represent the most technified sector of the cattle production, nevertheless it has challenges with profitability and competitiveness with the market of imported dairy products, which establishes a disadvantage for local production. However, the rearing of discarded calves for meat production, can be a competitive alternative. Objective. To deepen the management of feeding in the calves rearing stage from dairy farms. Development. Artificial breeding includes the management, care, and feeding of calves until weaning and its objective is to reduce the nutritionally dependent of milk, at the lowest age possible, and to be able to incorporate solid foods into the diet. The basic diet of the calves during rearing includes the colostrum, milk or milk replacer, concentrated feed, and forage. It must be ensured colostrum quality measurement and the offer of quality colostrum, in the first hours postpartum. Milk or milk replacer should be supplied for eight weeks maximum with a tendency to decrease the period without affecting the development of the calves, offering a product of compositional and sanitary quality. The concentrate feed and the forage source can be offered from the first weeks of birth, guaranteeing quality of the diet and removing the feed scraps to avoid gastrointestinal problems. Conclusion. Rearing as a critical stage requires strategic feeding management. The supply of quality colostrum at the right time is the basis of the entire production stage. Liquid diet is essential for the physiological and enzymatic adaptation of the gastrointestinal tract, while solid diet is essential for ruminal development.

Glycerol: dietary supplement and response in dairy cattle

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. Animal production technologies have allowed the efficient use of food resources to meet nutritional needs and generate food for the human population. Alternative feed sources in ruminants have been used to increase the productive and reproductive indicators. The expansion of the oil palm area (Elaeis guineensis) for biodiesel production as a renewable energy source has favoured the development of agro-industrial processes through the generation of by-products, such as glycerol, which due to its glycogenic effect, could be considered as an alternative energy source. Objective. To substantiate the nutritional effect of glycerol as a dietary supplement on the response in dairy cattle. Development. Studies have reported beneficial effects of the glycerol use as therapy in the prevention of metabolic disorders associated with the transition period, characterized by nutritional deficiencies and imbalances. Several results have shown that its response is associated with the level of inclusion (5 to 12 % DM) in the diet and the rate of disappearance at the ruminal level, which concerns the intake. Its composition varies according to the quality of the raw material (degree of impurities), which could be considered unsafe for its supply. The energy sources have shown a favourable effect on the reproductive response expressed by the increase in the ovulation rate, the improvement in the modulation of the uterine prostaglandin synthesis, better quality of oocytes, greater competition in embryonic development, and an increase in the conception rates, in which the use of glycerol could be associated. Conclusion. Glycerol could be considered an essential ingredient in diets due to its high energy value and beneficial effect on productive and reproductive indicators, however, it is necessary to expand its study.

Identification methods for Tomato brown rugose fruit virus (ToBRFV) in México

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The tomato brown rugose fruit virus (ToBRFV) was first reported in Israel and Jordan in 2014, causing damage to tomato crops in protected agriculture. Objective. To collect information on the known distribution, current situation, and detection methods of ToBRFV. Development. Between 2018 and 2019, the presence of the virus was confirmed in Mexico, the United States, China, Germany, Turkey, the United Kingdom, and Italy. Electron microscopy and serological tests have been used to detect the virus, but these cannot differentiate ToBRFV among other tobamoviruses. The most effective diagnostic technique for detection is specific oligonucleotides developed from the isolates from Israel and Jordan. Hygiene protocols are the most important step in preventing infections. Conclusion. Efforts to control ToBRFV are currently focused on the use of strict sanitation and detection practices in seed and plant, using molecular reverse transcriptase polymerase chain reaction (RT-PCR) techniques with specific oligonucleotides, which avoid false positives.

Current state of research for the guava cultivation in Colombia

Tue, 01 Sep 2020 00:00:00 -0600

Introduction. The guava (Psidium guajava L.) is considered a commercially important fruit in more than sixty countries, which is used in the agro-industry and fresh consumption, due to its nutraceutical properties, since it is considered an important source of vitamin C, thus improving the health of consumers. Objective. To determine the current status of research for the guava cultivation in Colombia. Development. The cultivation of guava in Colombia presents inadequate yields in the different producing regions, mainly due to the lack of knowledge on the part of the producers and the use of technologies that are not suitable for intensive production. However, there are currently a number of technological offers that can be implemented to address the main limitations of the crop, achieving as a result to improve the production of guava in a profitable and environmentally sustainable way. Conclusions. The technical recommendations and technological offers related to the use of improved varieties, agronomic, and phytosanitary management of the guava crop could be implemented by the producers, in order to position Colombia as an international reference to supply the domestic and export markets.

Productivity of dairy cows supplemented with silage of fava bean or fodder beet

Fri, 01 May 2020 00:00:00 -0600

Introduction. Milk production systems are affected by climate change, presenting seasonality in forage production, and added to this, breeds with high nutritional requirements predominate, which leads producers to permanently use concentrates that increase the costs of production. Objective. The objective of this work was to evaluate milk production and quality in cows supplemented with espadrille bean (Vicia faba L.) and fodder beet (Beta vulgaris L.) silage. Materials and methods. The study was conducted at the Obonuco Research Center of AGROSAVIA, municipality of Pasto, Nariño, Colombia. Twelve cows of the F1 breed (Kiwi Cross X Holstein) were used, of first childbirth (93 days of breastfeeding), with an average live weight of 460 kg. Cows were kept in paddocks with grasses, legumes, and water ad libitum. For three periods of fifteen days each, three levels of silage inclusion (0, 4 and 8 kg day-1) of bean and beet were evaluated, using a 3x3 Latin square experimental design for each species. Daily production of each animal was recorded and the compositional quality of the milk (fat, protein, total solids and milk urea nitrogen MUN) was determined. Results. With the highest level of inclusion (8 kg cow-1 day-1), the alpargata bean silage had an effect (p<0.05) on the protein percentage, while the fodder beet silage influenced (p<0,05) in the percentage of fat. Both species did not influence production, total solids, and MUN. Conclusion. The supply of bean and beet silage influenced the compositional quality of milk, providing food alternatives in the milk production systems of the upper tropics of Nariño, allowing seasonality and the replacement of common sources to be reduced.

Productive performance of Holstein and the crossbreding Kiwi Cross x Holstein cattle

Henry David Mogollón García, David Felipe Nieto Sierra, Edwin Castro-Rincón — Fri, 01 May 2020 00:00:00 -0600

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.