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Henry A.,Pennsylvania State University | Rosas J.C.,Panamerican School of Agriculture, Zamorano | Beaver J.S.,University of Puerto Rico at Mayaguez | Lynch J.P.,Pennsylvania State University
Field Crops Research | Year: 2010

Multilines (genetic mixtures) composed of genotypes of contrasting root architecture were hypothesized to show improved growth and productivity in comparison with genetic monocultures in conditions of multiple edaphic stresses. To test this hypothesis, three multilines of common bean (Phaseolus vulgaris L.), each composed of two recombinant inbred lines having contrasting root architecture in previous studies, were evaluated at seven sites in Honduras with varying soil phosphorus and moisture availability. Molecular markers were used to quantify the presence of each genotype in both root and seed-yield samples. Root growth in competition was dependent on both soil treatment and genotype. In one of the multilines, the root zone was dominated by one genotype, especially in the high-P treatment. In contrast, the root zone of another multiline had equal representation from both genotypes. These results show that response to belowground competition can differ among genotypes of the same species. No tradeoff between root growth and plant performance (yield or shoot biomass) was observed. Contrary to expected results, profiles of root distribution did not differ significantly in the environments tested in this study. As a result, differences in uptake of resources (phosphorus and water) in divergent soil domains and yield advantage of multilines were observed in only a small number of cases. Multilines did not create any yield penalty. Future work with genotypes that are more contrasting in root architecture is necessary to assess this strategy for use by resource-poor farmers. © 2010 Elsevier B.V. Source

Matamoros W.A.,University of Southern Mississippi | Matamoros W.A.,Panamerican School of Agriculture, Zamorano | Schaefer J.F.,University of Southern Mississippi
Journal of Fish Biology | Year: 2010

A new species of Profundulus, Profundulus portillorum, from the Honduran central highlands is described. Profundulus portillorum belongs to the Profundulus labialis species group and is distinct from the Profundulus punctatus species group in that it lacks a humeral spot and less than half of the caudal fin is scaled. Within the P. labialis species group, P. portillorum has a more slender body, smaller eye, fewer anal rays, caudal rays and lateral-line scales than other species. Forty-one specimens were collected around emergent vegetation in the margins of two small (2-5 m in width, 20-40 cm in depth), high-elevation (1300 m) tributaries of the Río Calam within the Río Ulúa drainage. These specimens represent the easternmost collection of any Profundulus and the first collection of any member of the P. labialis species group from Honduras. © 2010 The Authors. Journal compilation © 2010 The Fisheries Society of the British Isles. Source

Badillo-Saldana L.M.,Autonomous University of the State of Hidalgo | Ramirez-Bautista A.,Autonomous University of the State of Hidalgo | Wilson L.D.,Panamerican School of Agriculture, Zamorano
Revista Mexicana de Biodiversidad | Year: 2016

The establishment of grazing areas in humid tropical environments is one of the causes of amphibian population decline. This work evaluates the consequences of the establishment of grazing areas on amphibian communities in an area of the Sierra Madre Oriental using analyses of alpha and beta diversity. Sampling was conducted at 28 locations, 7 in tropical evergreen forest (TEF), 7 in mountain cloud forest (MCF), 7 in tropical grazing areas (TGA), and 7 in cloud forest grazing areas (CFGA) using the method of direct sampling. Amphibian diversity is reduced when the grazing areas are established in tropical environments (TGA, 8 species; 7.1 effective species and TEF, 10 species; 7.7 effective species); in contrast, the CFGA has a greater diversity (11 species; 9.3 effective species) compared with MCF (8 species; 3.9 effective species). The most dissimilar composition was found between the 2 communities of undisturbed forests (MCF-TEF; Jaccard dissimilarity 0.78). Establishment of grazing areas in TEF strongly influences the reduction of amphibian populations when compared with MCF. © 2016 Universidad Nacional Autónoma de México, Instituto de Biología. Source

Acevedo M.,North Dakota State University | Steadman J.R.,University of Nebraska - Lincoln | Rosas J.C.,Panamerican School of Agriculture, Zamorano
Plant Disease | Year: 2013

Bean rust, caused by the fungus Uromyces appendiculatus, is a major constraint for common bean production worldwide. Virulence of U. appendiculatus collected from wild and cultivated Phaseolus spp. was examined in 28 locations across Honduras. Host accessions representing wild and domesticated Phaseolus spp. collected at the same sampling locations were evaluated for resistance against U. appendiculatus. In total, 91 pathotypes were identified from 385 U. appendiculatus isolates according to their virulence on each of the 12 host differentials. No significant difference in pathogen total virulence, measured as the mean disease score, was found between locations. However, significant differences were found in pathotype virulence among isolates collected from different Phaseolus spp. within a location. Moreover, when locations were compared on the basis of pathotype occurrence and frequency, differences among locations were evident. No two locations had the same pathotype composition. The most common pathotype was virulent on 9 of the 12 differential lines. A high number of resistant accessions were identified in Phaseolus coccineus and P. lunatus. Although most wild P. vulgaris accessions were highly susceptible, rust resistance was observed in P. vulgaris landraces collected from farmer's fields. Thirty-two (52%) of the accessions screened showed intermediate to high levels of resistance and, of those, 16% were P. coccineus accessions. Our findings support the hypothesis that interaction of U. appendiculatus in host populations composed of diverse Phaseolus spp. and genotypes has favored highly diverse and virulent pathotypes, creating a center for virulence diversity of the pathogen in Honduras. The high percentage of intermediate and highly resistant accessions identified in the present study supports the strategy of collecting plants from the center of diversity of a pathogen or in locations with high incidence of disease and pathogen diversity to maximize the probability of identifying new sources of resistance. © 2013 The American Phytopathological Society. Source

Lascano G.J.,Pennsylvania State University | Velez M.,Panamerican School of Agriculture, Zamorano | Tricarico J.M.,Alltech Inc. | Heinrichs A.J.,Pennsylvania State University
Journal of Dairy Science | Year: 2012

An experiment was conducted to determine the effect of replacing soybean protein (SBM) with a slow-release urea (SR-U) in control-fed dairy heifers in the tropics. Eight Holstein heifers (237.6 ± 5.45. kg of body weight) were allocated to 2 treatments in a crossover design. Treatments were control (SBM) and SR-U (Optigen II; Alltech Inc., Nicholasville, KY). The forage-to-concentrate ratio was 50:50 [dry matter (DM) basis], and fresh chopped sugarcane was the sole source of forage. Data were analyzed using a mixed-effects model. Compared with the SR-U diet, SBM tended to have greater total tract apparent digestibility of DM and ash. Total tract apparent digestibilities in SBM-fed heifers were greater than in SR-U-fed heifers for organic matter (73.9 vs. 71.3 ± 0.6), crude protein (76.9 vs. 75.2 ± 0.7), hemicellulose (50.5 vs. 43.3 ± 0.9), and starch (98.6 vs. 97.1 ± 0.5). However, total tract apparent digestibility of neutral detergent fiber was similar, and digestibility of acid detergent fiber was higher in SR-U heifers than in SBM (33.3 vs. 27.7 ± 2.6). Water intake and excretion of urine and feces (wet and dry) were similar between treatments. Retained N was similar for all groups, and no differences were observed in the distribution of excreted N. We conclude that when SR-U replaced SBM, it tended to marginally decrease DM and decreased organic matter, crude protein, hemicellulose, and starch total tract apparent digestibility, but did not affect neutral detergent fiber and increased acid detergent fiber digestibility. © 2012 American Dairy Science Association. Source

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