bluuebunny/crossref_metadata_2025 huggingface dataset:
Validación técnica de inoculantes en frijol con cepas de Rhizobium eficientes en fijación de nitrógeno en Centroamérica.
Authors: Acuña Oscar , Rodríguez Emigdio , Llano Aurelio , Calderón Vilma Ruth , Flores Guillermo , Viana Abelardo , Lépiz Rogelio
Published: October 2018

Atechnical evaluation trial was carried out to evaluate the use of inoculants in bean with efficient Rhizobium strains, in oder to obtain more information about the usefulness of this technology in the common bean production. The regional experiment was planted in 45 localities distributed in Costa Rica (20), Panama (10), Nicaragua (10) and El Salvador (5), during 1998 and 1999. The experiment included four treatments: 1. Control; 2. Inoculation; 3. Half of recommended fertilization plus inoculation; 4. Recommended fertilization (Fer Rec). The inoculant was prepared and distributed by the University of Costa Rica. The variety and the fertilization utilized in treatments 3 and 4, were the recommended in each locality. The experimental plot varied between 50 and 100 m2 and a randomized complete block design with three replications was used. Thirty-nine trials were harvested and the seed yield and production costs were registered. The analysis of variance by production areas and countries, used the yield average by location; the economic analysis used the partial budget methodology. The results showed that: a) the bean response to inoculation and/or fertilization, varied among places; b) the regional analysis indicated bean response to the inoculant utilization and in the 80% of the cases, the economic analysis selected the inoculation treatment as profit; c) with the exception of Panama, the use of half of recommended fertilization plus inoculation, was better than inoculation only.
Exploración de la diversidad morfológica de chiles regionales en Yaxcabá, Yucatán, México.
Authors: Latournerie Luis , Chávez José Luis , Pérez Manuel , Hernández Carlos F. , Martínez Rodrigo , Arias Luis M. , Castañon Guillermo
Published: October 2018

The main objective of this work was to know the types diversity and uses of the pepper, selection criteria and to get samples samples of the landraces. The studied system was a multi-cropping system with corn, beans, pepper and pumpkin (milpa), established in two stages: a) a survey on 60 land-owners from the community, in order to gather information of the crop and their croppin systems applied in the ‘milpa’, pach pakal (land useful for gardening) and back-yards. b) An etnobotanical exploration to collect genetic material and to conduct an in situ assessment of the morphological characters of the plant, fruit and flower. Eight regional pepper types are grown in the community, seven belong to the Capsicum annuum such (yaax ic, xcat’ic, cha’hua, chile dulce, sucurre, pico paloma and maax, the latter C. annuum var. aviculare and one C. chinense (habanero). The yaax ic pepper is the most widely accepted in the community. The farmers base their germplasm selection on the fruit size, taste, pests and disease tolerance and culinary uses. The regional peppers are planted in association with other crops in the “milpas” as well as in the back-yards.
Evaluación agronómica de tomate (Lycopersicon esculentum M.) en invernadero.
Authors: Borrego Fernando , López Alfonso , Fernández José M. , Murillo Margarita , Rodríguez Sergio A. , Reyes Alfonso , Martínez Juan M.
Published: October 2018

The main objective of this work was to determine the adaptation potential of tomato genotypes for greenhouse. Genotypes evaluated were: hybrids: Contessa, Summer Flavor 5000, Summer Flavor 6000, Celebrity, Bonita, Shady Lady, Sunbolt, Sunny, Heat Wave and Olympic; and the variety Flora Dade, as a check. The variables evaluated were: yield, agroclimatic and physiological. agroclimatic and physiological variables were determine in three evaluations in the crop cycle, at three times/day and two leaf positions, in each evaluation. Significant correlations were found (p≤0.05) between yield in t/ha and mean yield by plant, fruits by plant at harvest, and yield by plant, and between photosynthesis and water use efficiency. Principal component analysis showed first five components have an Eigenvalue greater than one, explaining the first three with a 72% of total variance. The first component, with a 36% of total variance is due to “The yield characteristics” component two, with a 23% of total variance, is due to “internal temperature regulation characteristics” and component five, with a 7.4% of variation, to “photosyntates efficient production”. Multiple linear regression analysis difference was significant (p<0.01). Yield in t/ha was explained by the multiple linear equation (r2 =0.98) of four variables.
Efecto de la profundidad del suelo en Rottboellia cochinchinensis (Lour) Clayton en caña de azúcar (Saccharum officinarum L.).
Authors: León Ramón , Agüero Renán
Published: October 2018

Four sugarcane fields with different soil textures (clay loam, sandy loam, clay and loam) were sampled. All fields showed R. cochinchinensis populations with at least 75-150 plants/m2. The number of plants of this weed in 0.25 m2 was determined separately in the microhabitats: rows and between rows. The depth at which each plant emerged was measured. Based on depth emergence, each plant was distributed in one of the next categories: 0, >0-2.5, >2.5-5.0, >5.0-10 and >10.0-15.0 cm. In addition, under greenhouse conditions, seeds were seeded in pots at the maximum depth of each category in order to evaluate the effect of soil depth. Finally, the effect of light and darkness on seed germination were evaluated in Petri dishes under laboratory conditions. In the field evaluations most of the plants emerged from >0-2.5 cm. The second most common category was >2.5-5.0 cm. It seems that those depths provide optimum conditions for germination. There were no differences regarding soil texture or microhabitats. In the greenhouse experiment, the largest germination was observed at 0 cm due to light exposure in this treatment. This was confirmed in the laboratory where light treatment showed also the largest germination. Control strategies that keep the seeds of this species above ground will reduce the number of new seeds in the seed bank and avoid optimum field conditions for its germination. If such strategies include efforts to reduce the seed production of those plants that are able to become established, it could be possible to significantly reduce the seed bank, therefore, it would be easier to control the population of this weed.
Degradabilidad ruminal de la planta de maíz forrajero en diferentes edades de crecimiento.
Authors: Boschini Carlos , Amador Ana Lorena
Published: October 2018

The purpose of this study was to determine the ruminal degradability of dry matter of fodder of highland Costa Rica corn. The crop was planted with 50 kg of seed/ha, with 70 cm between rows, 50 cm between plants and three seeds in each hole. The first sampling was taken after 37 days and every two weeks thereafter, through 149 days. The potential degradability of the dry matter of the leaves, stems and the corn ears was determined. The potential degradability of the whole plant diminished from 93% to 74% as the age of the plants increased during the first 90 days. In the stem, the soluble part diminished from 40% to 27%, while in the leaves it remained constant between 15% and 16%. The degradable part of the stem diminished from 55% to 43% during the growth of the plant, and the leaves varied between 67% and 74%. The degradability rate of the stem was above 5% /h through 65 days and in the leaves it was lower. From the 79th day on, the leaves had a degradability rate above 5%/h and the stems had low rates. After the 107 th day the ears had a potential degradability of 85% and a degradability rate of 7.5%/h.
Microflora en semillas de frijol (Phaseolus vulgaris L.).
Authors: Membreño José B. , Zapata Mildred , Beaver James , Smith Rusty
Published: October 2018

The bacterial microflora present and its relationship with Xanthomonas campestris pv. phaseoli (Xcp) were studied in bean seeds, on 118 genotypes coming from VIDAC - 98, INTA - Nicaragua, TARS - USDA and Isabela - P.R. Five isolation methods were used: seed decontaminated with sodium hypochlorite, seed treated with refrigerated nutrient broth for one hour, dispersion of 0.1 ml of suspension of seeds between solid, liquid sowing of 1 ml suspension and seed in nutritious, agitated broth and refrigerated by 24 hours. One hundred and four yellow colonies from 41 genotypes were isolated. Thirty-six colonies were positive KOH (Gram negative), 68 negative (Gram positive) and 34 were starch hydrolyzers. The yellow colonies were nonpathogenic under greenhouse conditions. These were identified with the BIOLOG system as: Pantoea agglomerans (25), Xanthomonas campestris (2), Enterobacter agglomerans (2), Sphingomonas paucimobilis (2), Pseudomonas fluorescens and Flavimonas oryzihabitans. In addition, the genotypes carried colonies with other pigmentations. Antagonistic colonies were identified with deoxyribonuclease activity and antibiosis to Xcp. Of these, 15 colonies inhibited Xcp significantly. The fungi were identified as: Rhizoctonia solani, Penicillium spp., Fusarium spp., Aspergillus flavus, Rhizopus nigricans and Macrophomina phaseolina in 52.9% of the total evaluated genotypes.
El banco de propágulos de malezas en el agroecosistema: conocimiento actual y propuesta metodológica para su estudio.
Authors: Acosta Luis , Agüero Renán
Published: October 2018

The goals with this paper are to review the processes that regulate seed banks in agroecosystems, their horizontal and vertical distribution in the soil, as well as to present a simple methodology for the study of the seed banks size, regeneration potential and seed spreading. We focus mainly on internal and external factors regulating growth and exhaustion of seed banks, the impact of tillage on transitory and permanent banks and aspects related to germination and dormancy of seeds. In agroecosystems, the propagule banks constitute the primary resource ensuring the perpetuation of weeds; even if only a small portion remains, there will be weeds during the next growing season. A broad knowledge of these banks and their dynamics might prove useful for future rational schemes of weed management.
Producción y calidad de la biomasa de morera (Morus alba) cosechada en diferentes modalidades de poda.
Authors: Boschini Carlos
Published: October 2018

A plantation established in 1993 with 60 cm, 90 cm and 120 cm between rows, was harvested 60 cm above the ground, 26 times at different pruning intervals between 56 and 112 days. Three pruning techniques were used: control, semi-clean and completely clean. Every 84th day of growth, the shoots were harvested and the total content of dry material, crude protein, neutral detergent fiber and ash were analyzed. The semiclean pruning caused a 10% loss in the production of dry leaf material per hectare and a 13% in the stem yield, compared to the control. The joint harvest of leaves and stems decreased 11%. The completely clean pruning caused a 32% decline in the yield of dry material in the leaves per hectare and 36% in stem production, compared to the control. The total yield decreased 33%. The nutritional quality of the shoots, leaves and stems was similar among the different pruning techniques.
Efecto de la densidad de siembra sobre el rendimiento y calidad del forraje de maíz.
Authors: Elizondo Jorge , Boschini Carlos
Published: October 2018

The experiment was condunted at the Alfredo Volio Mata Experimental Station of the University of Costa Rica, located at 1542 meters above sea level. The purpose was to determine the effect of plant density on total forage mass and the nutritive value of corn. Three diferent plant distances were used: 30 x 70 cm, 50 x 70 cm and 70 x 70 cm resulting in 47619, 28600 and 20449 plants per hectare, respectively. The first sampling was taken out 42 days after establishment and every two weeks thereafter, until 126 days. Dry matter, crude protein, ashes, neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin were analyzed for different parts of the plant. The values for celulose and hemicelulose were calculated. Total forage mass (kg/ha) was greater at higher plant densities. Dry matter content of leaves was higher than in stems, all of the plant densities. No significant difference (P<0,05) was found for crude protein content in the different parts of the plant. ADF was always higher in stems than in leaves. Stage of growth considerably affects biomass yield and nutritional quality of fodder. Before 70 days the dry matter content in leaves was higher than in stems. Latter accumulation of dry matter in stems was greater than in leaves. Crude protein content in leaves was over 18% during the first 70 days, then decreases a level of 13% at the end of the period. The lowest value of ADF was found before 84 days in leaves and stems. Under the enviromental conditions of this experiment, it appears that plant densities of about 48000 plants per hectare are optimal.
Fertilización y densidad de población en genotipos de maíz cultivados bajo condiciones de temporal.
Authors: Cano Octavio , Tosquy Oscar Hugo , Sierra Mauro , Rodríguez Flavio Antonio
Published: October 2018

During the rainy season in 1998/98 a reseach was conducted in Campo Experimental Cotaxtla, Veracruz, México, with the objectives of knowing the response of five corn genotypes to doses fertilizer and plant density. A completed randomized block experimental design with two replications was used arranged in split plots where the genotypes (G) VS-536, H-512, H-513, HTV1 and HTV2 were considered as small plots ; The medium plots were doses of fertilization (F) of N2,P2O5,K2O: 161-46-0, 184-69-0, 184-69-30, 207-92-0 and 207-92-30 ; and the big plots were plant densities(D): 50, 62.5, 75, 93.75, 100 and 125 thousand plants/hectare. The characteristics studied were: harvest index, ears per plant, and grain yield. The analysis of variance showed significant differences for some characteristics in D, F, DxF y DxG and for all in G. According to this, the best genotype was the experimental hybrid HTV1 with yield 6.74 t/ha. The response to fertilization was only of to harvest index, where the best dose was 184-69-0. In relation with plant density, with 62500 plants/hectare, all genotypes showed their best yield and number of ears per plant.
La labranza mínima como práctica de producción sostenible en granos básicos.
Authors: Rojas Luis A.
Published: October 2018

In the present the agriculture and livestock field and specifically the basic grains producer, goes throught the worst crisis in the whole history of Costa Rica. The strong degradation of the natural resourses, linked to the important low yield of the crops, which also coincide with the high cost of production, have been increasing the problem. On the other hand, the lack of policies of the last Costa Rica government hastens the crisis. Right now, the basic grain crops do not produce economic profit, so it’s impossible to contonue producing with high costs, as machinery, excessive use of chemical and other inputs. We are looking for a system to approach and to assess lower cost alternative with high agricultural return. The basic grain sowing within of non-tillage system, conservation tillage o direct sowing, is a great production alternative, with high income and profit in the short, medium and long term; which includes physical, chemical and biological improvement of the soil and reduce the production cost. The Agronomy School at the Costa Rican Tecnological Institute are currently working in the project with different non- tillage activities like research, technological transfer, and non-tillage cropping system in basic grain, as sustainable alternative in the Huetar Norte region of Costa Rica and others parts of the country.
Alternativas para favorecer la polinización y producción de semilla del híbrido H-311 de maíz.
Authors: Espinosa Alejandro , Tadeo Margarita , Medina Hortencia , Gutiérrez José Ricardo , Luna Maximino
Published: October 2018

For corn hybrid production it is fundamental that progenitors’ flowering coincide and that the availability of stigma with respect to tassels. The H-311 hybrid is recommended for irrigated, at altitudes between 1200 and 1800 meters above sea level. The initial cross order was: (B16XB17) X (B32XB33); however, the order was reversed, that is (B32XB33) X (B16XB17), due to a higher productivity and seed quality. The B16XB17 is dwarf (braquitic), and during pollination under insufficient wind, breeding is difficult and it is necessary to use motorized knapsacks to rise pollen, the simple cross B16XB17, yields from 4.5 to 5.5 t/ha of seed, compared to 6.0 to 7.5 t/ha of the simple cross B32XB33; The simple cross B16XB17, responds with increased height with the treatment with giberelic acid (Activol), at 20, 40 and 60 ppm, two applications of Meqiquat Chloride (PIX), 1 and 2 l/ha, as well as three fertilizer levels (400-70-30, 150-70-30 y 150-300- 30). There was a yield effect due to management of both progenitors with different fertilizer levels, as well as with the use of fitohormones, with the application of giberelic acid (20 ppm), the yield increased 250.3%and 211.8% for the simple crosses B32XB33 y B16XB17, respectively. The plant height of B16XB17 was slightly affected (106% with 40 ppm of giberelic acid).
Periodos de solarización y adición de gallinaza sobre la sobrevivencia de propágulos de Cyperus rotundus, Rottboellia cochinchinensis y Bidens pilosa.
Authors: Herrera Frnaklin , Ramírez Carlos
Published: October 2018

From October 1994 to February 1995 a field trial was conducted at the Fabio Baudrit Agricultural Experimental Station, University of Costa Rica, to evaluate the effects of different periods (weeks) of solarization, namely: 0, 2 (103), 4 (188) and 7 (288) - figures in parenthesis are cumulative hours of sunshine - in combination with chicken manure additions (4,1 t/ha) on propagule survival of the weeds Rottboellia cochinchinensis, Bidens pilosa and Cyperus Rotundus. The propagules were placed at the following depths (cm): 0-5; 5,1-10; 10,1-15; 15,1-20 and 20,1-25. In additional an inventory of the native weed seed bank was conducted as well as the growth and yield of cilantro Coriandrum sativum as an indicator crop. The greatest propagule death occurred after 7 weeks of solarization, the addition of chicken manure further decreased the propagules of C. rotundus and B. pilosa. This treatment also sharply decreased the soil weed seed bank, shorter periods not were as effective. Growth and yield of the indicator plants increased in the seven week treatment by 320 %. In addition the roots looked better developed and lacked the root-nodule nematode galls caused by Meloidogyne arenaria that were observed in the control treatment. The economic benefits of solarization in the context of the indicator plant is discussed.
Caracterización de la calidad tecnológica y nutricional, de variedades mejoradas y criollas de frijol negro tropical (Phaseolus vulgaris L.).
Authors: Ortega Dora Alicia , Vinay Julio César , López Ernesto
Published: October 2018

With the objective of characterizing the technological and nutritional quality of improved varieties of the tropical black bean, released by the INIFAP in the humid tropics, this study took place in the Cotaxtla and La Posta Experimental Fields. It included the tropical varieties: Jamapa, Negro Huasteco-81, Negro Veracruz, Negro Cotaxtla-91, Negro Tacana, and two local creole varieties: “Arbolito” and “Palito”. We performed the quantification for humidity (%), weight (g), size (mL), head (%), water absorption (%), cooking time (min) (Mattson and Sensorial methods), cooking rate (%), broth thickness, protein (%), crude fiber (%), fats (%), dissolved carbohidrates (%), triptofane (g/100 g of protein), germination (%), myco-flora (%). The improved varieties presented very good technological quality; they were characterized by materials of small bean, soft and bland; they had very similar cooking times and a cooking rate of > 47 %, characteristic of recently harvested beans. They provided a light broth. They all had very good nutritional quality and the Negro Veracruz was the one with the largest protein content (27%), and Negro Tacana, with the best concentration of triptofane (1.27 g/ 100 g of protein). The seed quality was very good and the best one was Negro Veracruz with a 99% of germination rate, and Negro Cotaxtla-91 with only 10% of myco-flora.
Eficiencia del uso del fósforo en diez genotipos de frijol común (Phaseolus vulgaris L.)
Authors: Gómez Luis A. , Vadez Vincent , Hernández Germán , Sánchez Tamara , Toscano Vidalina
Published: October 2018

Ten common bean genotypes (Jamapa, APN18, Carioca, Río Tibají, Porrillo, Pot 51, Bat 271, Bolita 42, Calima y CC25-9N) were grown in an intensively aereated nutritive solution with 5 weekly doses of phosphorus (0; 62,5; 125; 187,5 and 1875 mM/plant) and 2 mM of N in the form of KNO3. The objective was to evaluatefoliar biomass and its P content, as well as, to calculate the P Use Efficiency (PUE) parameter based on these and relate them with the concentration levels with which plants were nourished. The optimum requirement level obtained fromboth biomass and PUE criteria ranged between 62,5 - 187,5 mM/plant/week; this supported differences for P nutrition within the genera. Pot 51 showed the lowest requirement and Carioca the highest for optimum yielding; but Bat 271 exhibited the highest efficiency index even at a suboptimum level. Among these genotypes, CC25-9N showed the lowest efficiency and Porrillo showed no variation for this parameter. It may be concluded that the highest efficiency point coincided in 80 % of the cases with the maximum biomass production point.
Efectos genéticos en híbridos de maíz tropical (Zea mays L.) III. Acame, mala cobertura y pudrición de mazorca.
Authors: Martínez Gaspar , De León-Castillo Humberto
Published: October 2018

This study report genetic effects for lodging, uncovered ears and ear rot, of 42 single cross hybrids made with seven lines developed in the humid tropic of México, and six lines developed in the dry tropic, using a North Caroline II mating design. Hybrid variation was mainly due to GCA variance, and scanty to SCA variance for all the three attributes, although for ear rot, SCA variance had a considerable role, too. Partitioning GCA variance, revealed humid tropic lines had highest contribution to lodging and ear covering variance, and dry tropic lines the highest contribution to ear rot variance. In addition, humid tropic lines had higher GCAxEnvironment interaction variance than dry tropic lines. In conclusion, GCA effects, which reveal additive genetic variance, were the main effects for all the three attributes, and that GCA effects were higher in humid tropic lines than those of the dry tropic, maybe due to their mobilization in a more ample and diverse region.
Mejoramiento de la línea MLS4-1 de maíz (Zea mays L.) a través del método de retrocruza.
Authors: Arreola Jesús , Burciaga Gustavo , Gutiérrez José , Vega Cristina , Navarro Enrique
Published: October 2018

This research work involves the improvement of the male line MLS4-1 of the hybrid AN-388 which was released by the Instituto Mexicano del Maíz of the Universidad Autónoma Agraria “Antonio Narro”. This line has excellent combining ability with other parental lines; however, it is susceptible to some diseases so that we are interested in improving it by using the backcross procedure. The Nepo population was used as a source population which is resistant to mildew spp. Three backcrosses and two recombinations were practiced before deriving lines and cross them with some testers. The objectives of this work were: 1. To evaluate the performance of recovered lines in combination with the original line MLS4-1, and with un-related testers, taking into account their combining ability and agronomic traits in relation to the hybrid AN-388, 2. To now the effectiveness of the backcross method to improve the MLS4-1 line. The results of this study allowed us to identify superior recovered lines that, in combination with the diverse testers, exceeded the agronomic value of thehybrid AN-388. Some recovered lines crossed with the MLS4-1 line produced excellent single crosses, indicating the possibility of getting new versions of the hybrid AN-388. Finally, we conclude that the improvement of the MLS4-1 line has permitted us to identify the best lines with higher combining ability and better agronomic traits.
Evaluación de aceite e insecticidas para el control del virus del mosaico dorado (VMDF) del frijol en Chiapas, México.
Authors: Becerra Noé , Fraire Guillermo , López Ernesto
Published: October 2018

Upon evaluating the effect of two mineral oils and two insecticides on the control of the BGMV in three genotypes of black bean, it was found that the variety Negro Tacana given its resistance to the virus, they can or cannot use the products. In Negro Huasteco-81 we could employ this type of products, in order to disminish incidence and increase yield, from 126 kilos with the treatment of Citrolina + Endosulfan; upto 320 kilos with the combined products of Imidacloprid 70 WS and 350 SC and of 281 kilos with Imidacloprid 70 WS. In Negro Cotaxtla-91 can there be are increment of 82 kilos with the treatment of Citrolina + Endosulfan.
Efecto de la concentración de fósforo sobre su asimilación en tres genotipos de frijol común (Phaseolus vulgaris L.)
Authors: Hernández German , Toscano Vidalina , Méndez Nancy , Gómez Luis , Mullings Miguel
Published: October 2018

The experiment was carried out under green house conditions using 1000 cc pot hidroponic thechniques; it was oxigenated with 400 ml.l-1.minutes-1, where common bean plants arranged in randomized block design. The effect of 0; 0.25; 0.50; 0.75 and 1.00 mm of phosphorus concentration over the biomass developed by leafs, leafstalks, stalks, roots, pods; total biomass; the total plant phosphorus concentration and the phosphorus use efficiency shown the common bean variations (Phaseolus vulgaris L.) such as CC25-9(N), BAT 58 and BAT 304, were studied. There was found significative difference between the amount of biomass formed by leaf, stalk, pods and, the total plant biomass; the total plant phosphorus concentration changed in order of the phosphorus solution concentration used; while the phosphorus use efficien reached the uppermost value at 0.50 mm of phosphorus concentration. There is specific phosphorus incidence over the nutrition of bean genotype. The results showed that the different bean genotypes have different phosphorus requirements.
Evaluación de fungicidas en el control de la roya del frijol (Uromyces appendiculatus).
Authors: González Miguel , García Evelio
Published: October 2018

Five trials using a randomized complete block design with four replicates were performed to determine the effectiveness of several fungicide treatments against the bean rust as well as their effect on yields. The chemicals screened were bitertanol, diclobutrazol, diniconazole, hexaconazole, iprodione, metiram, oxycarboxin, penconazole, pyracarbolid, triadimefon, triadimenol and tridemorph + maneb which were compared with sulphur, used as standard and with an untreated check plot. The best results were obtained with Bitertanol 30 EC, Hexaconazole 5 SC and Oxycarboxin 75 WP sprayed at 0.5 kg/ha on a 14 days interval. No significative differences were found among the treatments, which statistically excelled Sulphur 80 WP sprayed weekly at 3 kg/ha and raised the yields significantly inrelation with it.
Seguridad alimentaria y desarrollo sostenible en las laderas de Centro América: retos futuros para la investigación y la formulación de políticas.
Authors: López Michael , Mendoza Fernando
Published: October 2018

Central America is facing serious problems concerning erosion and poor management of natural resources. Poverty is usually the source and cause of such problem as well as the high population growth. One major problem is the intense usage of mountain slopes in the production of basic grains under traditional migratory agricultural methods. It is a well established tradition to consider these areas as a source of cheap labor force and also as a region of subsistence for a rural impoverished population. Nevertheless, a high percentage of both the population and agricultural production of Central America is to be located in such areas, and mountain slopes constitute over 80% of the regional extension. This document presents an anylisis of the perspectives for sustainable development in the mountain slops of Central America and the challenges faced by researchers and by those in charge of planning and implementing development policies in the area. With different degrees of intensity, all area countries are facing the same problems in their mountain slope areas; as a result, it is necessay to generate information on the development of new methods, adequated to the exploitation of mountain slops, the formulation of local and national policies, the coordination with institutions which take into account the local reality and the need of a sustainable development of the region.
Agroecología del sistema de aboneras en el litoral atlántico de Honduras.
Authors: Triomphe Bernard
Published: October 2018

The present study constitutes an initial effort to provide baseline information about the internal workings of the mucuna system. It includes a discussion of biological mechanisms which shape this system, especially with regard to nutrient cycling. Long-term trends in soil chemical and physical fertility are also analyzed. Chronosequences (also known as space-for-time substitution schemes) form the backbone of this long-term analysis: they were constructed by taking advantage of the diversity of adoption dates of the mucuna system among farmers. All field measurements were made at the level of small observation plots selected on uniform backslopes within farmers’ fields and subjected to a periodic agronomic monitoring throughout the maize growing season. After describing general characteristics of the mucuna system, an analysis of the various pools participating in nutrient cycling is conducted. Mucuna biomass accumulation and descomposition are then discussed, as well as the dynamics of mineral nitrogen in the soil profile, an analysis which in turn helps understand maize response to limited applications of nitrogen fertilizer. Although it appears that the mucuna system is too specific to the conditions prevailing in the North coast of Honduras to be extrapolated directly. After 12 years or more of continuous use of the mucuna rotation, a result which can undoubtedly be attributed to the high yearly organic additions and efficient nutrient cycling in this system.
Combate biológico de Hydrilla verticillata Vahl con carpa herbívora (Ctenopharyngodon idella Vía).
Authors: Rojas Manuel , Agüero A. Renán
Published: October 2018

Hydrilla verticillata has become an important aquatic weed of irrigation canals at some rice farms of Guanacaste, Costa Rica. This species slows water flow, often causing flooding in adjacent roads, its control increases overall production costs. To evaluate efficiency of the grass carp in controlling Hydrilla three trials were conducted, with varying densities of the fish. In the preliminary trial, 987 kg/ha of grass carp reduced Hydrilla biomass in nearly 62 m3 in 21 days. During the second trial, treatments with 1264 and 2042 kg/ha of the fish completely eliminated the weed after 30 days. However, during the third trial, 1000 kg/ha of the carp only reduced Hydrilla volume in 19 m3, after 66 days. The ratio kg of carp/initial volume of Hydrilla proved to be more important than just the kg/ha of the carp. It was observed that when such ratio was lower than 0.02, the carp did not provide a satisfactory control of Hydrilla; on the other hand, a ratio higher than 0.05 significantly reduced the weed's biomass. The equilibrium point between weed regrowth and biomass consumed by the carp occurred at a ratio close to 0.03.
Eficiencia de cebos como atrayentes de moscas de la fruta en El Salvador.
Authors: Delmi Muriel , Morán Salvador , Núñez Fernando , Granados Gilberto
Published: October 2018

With the goal of determining the most efficient food bait for augmenting the capacity to capture adults of some species of fruit flies and also to find an alternative to hidrolized protein, this research project took place in “Finca Maravi”, in Planes de Renderos, Department of San Salvador, a 930 msnm. The design which was used was the one with randomly located blocks with five treatments and four repetitions. The McPhail glass trap was utilized. The efficiency of treatments was determined by the amount of captured flies, by trap, by day (F.T.D). The analyses indicated significantdifferences among them, but it was observed that orange juice is the most efficient food bait, capturing an average of six times more fruit flies than hidrolized protein. Urea with molasses also rendered high capture yields, statistically equal to those of hidrolized protein. The results which were obtained, indicated that food bait could play an important role in the integrated management of fruit flies.
Diseño de un sistema de análisis financiero de modelos de finca para proyectos de desarrollo rural.
Authors: Rojas Adrián
Published: October 2018

The following text describes an system which measures the financial factors that show the feasible production level of farm models. It also provides the basis to evaluate investment plans and paying capacity. This system permits to enter the costs and income of each tillage per year. Moreover it contains the income and costs the farm models. This information is included and brought up to date by the system. It will permit to make projections of cash flow not only before but also after the financing. The objective is to evaluate the effect of the financing over the investment made in a separate way. It also has the capacity to store information for several crop farm models an it is allowed to make the corresponding changes to each piece of data. In addition it offers a sensitivity analysis with percent variations in the cost and income.
Factibilidad del uso de raciones líquidas y pastosas en alimentación de cerdos en etapa de engorde-acabado.
Authors: Trigueros Rafael O.
Published: October 2018

It was the objective of this study to evaluate the efficiency of using liquid and paste food rations during the feeding of hogs, specifically the water-concentrate proportions in order to provide a significant weight gain and a larger food conversion. We utilized 40 inbred pigs of the Landrace, Yorkshire and Duroc breeds, in an experimente that lasted 60 days, with a number of treatments of 4, with 10 repetitions for each one, where we evaluated the water-concentrate ratios of 0:1,5 1:1 and 2:1. The result which were obtained showed that the value of food was improved when it was administered in a moistened form. The weight gain was presented as a significant response (P<0.001) during the treatment Nbr. 3, that is a water-concentrate ratio of 1:1. We did not observe any significant differences (P<0.001) in the remaining treatments. Data obtained showed a similar behavior in relation to the daily gain. The food conversion showed best results with treatments 2 and 3, which did not show differences between them. The results obtained in the experiment indicated that the food value of concentrates improves when supplied in a moistened form.
Predicción, del peso vivo en ganado bovino, a partir de mediciones corporales.
Authors: Mejía Napoleón , Velázquez Claudia , Tewolde Assefaw
Published: October 2018

This study took place in a cattle ranch working with double-purpose cattle, in the Department of Jutiapa, Guatemala, with the objective of calibrating a model of cattle measuring tape, with body measures, during the months of April, May and July, 1993. The measures were taken from 456 cattle heads, and the measuring variables comprehended: the torax diameter (TD), the body lenghth (BL), the live weight in kilograms (LW), and the age in years (AG). Cattle food was mainly pastures of “African Star” and “Jaragua” varieties, and other natural species. The herd produces milk all year round with a daily milking, and calves suckle until eight months old. The cattle measurements information was analyzed throughout fixed-effect models, including the TD, BL and AG variables, to determine the contribution of each effect for the live weight predictions. Two lineal multiple regressive models were adjusted by natural logarithm and by base-10 for males and females respectively. The analysis determined that in the studied population, the TD, BL and AG variables can be used to predict the live weight, according to the animal’s sex.
Evaluación de sistemas de mecanización, en el cultivo de soya de temporal, en el Centro de Veracruz.
Authors: Campos Santos , Uresti Jesús , Cadena Martín , Jácome Sergio , López Ernesto
Published: October 2018

The objective of the work was the evaluation of the soybean no-till system as a mean of reducing production cost without affecting the crop yield also toperform an economical analysis comparing this system with the traditional one. There was evaluated the performance of three different furrow opener under no-till system; the results showed that the better crop response was obtained with the chisel type furrow opener compared with the double disc. Also was tested the effect of planting depth and seed density over the effect of final stablished plant, these results showed that it is necessary to increase by 15% the seed dendity compared with the traditional system and the better planting depth response was obtained between three to four centimeters. The economical analysis showed that with the no-till system was possible to obtain a higher marginal return rate of investment in the order of 127% compared with 105% of the traditional system.
Desarrollo de germoplasma de maíz para el altiplano de Guatemala.
Authors: Fuentes Mario R.
Published: October 2018

The methodology used included the collection of native maize varieties within the region, their evaluation in contrasting environments, and the development of populations. The selection squeme included the evaluation of progenies in farmers’ fields and recombination in the research station in order to avoid environmental changes. With such a system, we have improved the populations V-301, V-302, Barcena 71, V-304, V-305, Don Marshall and Chanin, all adapted to the Central plateau, and the populations of San Marceno, Guateian Xela, Compuesto Blanco, Toto Amarillo and Chivarreto, for the Occidental Plateau. The yield response to selection was positive, with gains up to 4, 3% per cycle and with a reduction in plant height and a better location of the ear in the plant. The yields for the improved varieties at the farmers’ fields, showed an average of 21 and 41% higher yields in comparison to the check for the central and the occidental plateau, respectively. Reports from the “Rural Socio-Economy” program indicated that the improved varieties were adopted by 50% of the farmers who participated in the technology transfer activities in the region.
Respuestas correlacionadas para el rendimiento en la selección de híbridos de maices precoces subtropicales.
Authors: Preciado Ernesto , Terron Arturo , Córdova Hugo , Mickelson Harold , López Raimundo
Published: October 2018

With the aim of designing selection criteria to identify the described genotypes with short vegetative period and longer grain-filling period without increasing the total growing cycle of the genotype. The information generated during 1995 at six locations in the subtropical region of Mexico was used. A serie of six experiments, integrated with a group of subtropical hybrids derived from a diallel between a group of elite tropical and subtropical inbred lines from CIMMYT, were evaluated in collaboration with INIFAP and the seed industry. In the combined analysis of six environments, early hybrids with a grain yield of 8.0 t/ha were identified; those hybrids were 14 days earlier to reach physiological maturity than the control check which yielded 7.4 t/ha. The genotypes with lower yields showed a short grain filling period compared to the vegetative period. Correlations among yield vs. days to physiological maturity, grain-filling period and the index calculated by dividing the between grain-filling /days to physiological maturity were 0.47, 0.53 and 0.41, respectively. This indicate an intermediate association between these traits; also, a high correlation values were observed between grain yield vs. plant and ear hight. The correlation between yield vs. days to silk and days to pollen shed were not significant. General combining ability (GCA) and specific combining ability (SCA) effects were significant for yield, days to silk and grain-filling period. Sufficient variation was observed to allow for the selection of genotypes with short vegetative periods and longer grain filling periods. The effects of GCA and SCA for grain-filling period suggest that this trait is an important criterion to select parents for producing short season hybrids.
Las asociaciones maíz-leguminosas: su efecto en la conservación de la fertilidad de los suelos.
Authors: Alfonso Claro , Riverol Mario , Porras Pedro , Cabrera Eduardo , Llanes Juan , Hernández Juan , Somoza Víctor
Published: October 2018

During a three-year period from 1993 to 1995, experiments were conducted to determine the effect of the maize-legume associations on soil fertility and their impact upon the yields of subsequent bean crops. We studied under Research Station conditions on an Oxisol soil and on drainage plots in Ultisol soil, the following associations: for the agro-ecosystem South of Havana oxisol we considered maize + caupi; maize + velvet bean; maize + canavalia; maize + crotalaria; maize + sesbania. While for the agro-ecosystem of San Juan and Martinez (Utisol) treatments were : maize, maize + caupi; maize + velvet bean; maize + canavalia; millet and fallow soil. The results showed that the intercropping of maize with legume was beneficial on the evaluated soil properties, and that, if combined with minimum tillage in the Oxisols , they complement the beneficial effects of both agronomic practices of that type of soil. The impact of these legume-maize-treatments in the subsequent cultivation of beans was significant on seed yield compared to the obtained after maize alone. The nutrient balance was favored by the recycling of nutrients from green manure left by the legume-maize treatments used. The recycling if nutrients made possible a nitrogen reduction of 25%, and one of 100% for P2O5 and K2O. In the Ultisol soils drainage plots where established, in addition to the mentionated effects, we observed an anti-erosive impact of the treatments which diminished soil losses as compared to maize alone and fallow soil.
Consecuencias indeseables del uso de los plaguicidas en el ambiente.
Authors: García Jaime E.
Published: October 2018

Some of the negative collateral effects on the environment by the use of pesticides are described. In addition, the main conditioning factors that induce poblems to occur with more frequency and intensity in developing countries, as compared to the industrialized countries, are noted. Finally, some options and provide examples aiming to decrease or eliminate the use of those substances and, consequently, the problems related to the use of pesticides, are suggested.
Recolección de especies silvestres de papa en Guatemala.
Authors: Spooner David M. , Martínez Vicente , Hoekstra Roel , Van den Berg Ronald G.
Published: October 2018

The objective of this collection o fpotatoes expedition was to collect germplasm of potatoes wild species for their conservation and regeneration to put them available to the international scientific community as well as to gather field data to carry on taxonomic studies. Atotal of accessions of five species was collected. Thirteen accessions of Solanum agrimonifolium were collected in the Huehuetenango, San Marcos, Quetzaltenango, Totonicapán, Sololá and Chimaltenango provinces located in altitudes ranging from 2,340 to 3,300 meters above sea level (masl); six accessions of S. bulbocastanum subsp. partitum were gotten in the Huehuetenango and Baja Verapaz provinces; 17 accessions of S. clarum were found in the Huehuetenango, San Marcos, Sololá, and Totonicapán provinces in altitudes extending from 3,000 to 3,500 masl; on1y one accession of S. demissum was found in Totonicapán province; and six accessions of S. morelliforme were gotten in Huehuetenango, San Marcos and Totonicapán provinces in altitudes ranging from 2,900 to 3,050 masl. The habitats where these species grow are very dist urbed due to deforestation and changes in the use of the soil. As a result, the guatemalan potato wild species are endangered species. It is notorious that in many locations where 50 years ago wild germplasm was gathered it no longer exist.
Híbridos dobles de maíz formados con líneas mejoradas por selección gamética y retrocruza.
Authors: Navarro Enrique , Burciaga Gustavo , González Salvador , Vega M. Cristina , Morones Regino , Sandoval Elias
Published: October 2018

This research work includes the evaluation of 1040 double cross hybrids which were produced from single crosses improved by gamete and backcross procedures. Single hybrids were crossed with five testers. The yield trials were carried out during 1991 at Gómez Palacio, Durango, México, and the goals were as follows: 1) To evaluate the performance of double cross hybrids and 2) To determine the main agronomic traits on the observed variation. For grain yield, the double cross hybrids formed with single crosses improved by gamete selection performed better than those obtained by backross whose yields were adobe 11,6 t/ha (23% with respect to the best backcross genotype). The outstanding yields observed across the gamete procedure are probably due to the low percentage of rot ers. On the controry, the single crosses improved by backcross procedure showed early to flower, short height and had less problems ofboth root and stalk lodging. The best testers were AN258-18-19 x MLS4-1 and the AN 232 x 255- 18-19 when crossed with some single crosses yield more than 14 t/ha. It is import to mention that the outstanding grain yields were associated with values of general combining ability with the gamete selection. Finally, the multivariate analysis showed that two-thirds of the observed variation in the double cross hybrids was given by grain yield and clean grain yield, plant and ear height, male and female flowering.
Evaluación del potencial productivo del sorgo negro forrajero (Sorghum almum).
Authors: Araya Eugenio , Jiménez Carlos , Soto Henry , Quan Anité
Published: October 2018

Information on productivity and nutritional composition of forage black sorghum or Columbus grass (Sorghum almum) was obtained though five cuts, 63 days long each one. The first cut was in October - November 1991, the second in December 1991 - January 1992, the third in February - March 1992. A second set of cut took place with the fourth cut in September - October 1992 and the fifth in November - December 1992. The variables evaluated were Neutral Detergent Fibrous (FND), Dry Matter (MS), Dry Forage by Hectarea (FSH) and Crude Protein (PC), but only FSH, MS and FND tumed to be significantly important (P<0,01).