415 research outputs found
Agricolae - Ten years of an open source statistical tool for experiments in breeding, agriculture and biology.
Plant breeders and educators working with the International Potato Center (CIP) needed freely available statistical tools. In response, we created first a set of scripts for specific tasks using the open source statistical software R. Based on this we eventually compiled the R package agricolae as it covered a niche. Here we describe for the first time its main functions in the form of an article. We also review its reception using download statistics, citation data, and feedback from a user survey. We highlight usage in our extended network of collaborators. The package has found applications beyond agriculture in fields like aquaculture, ecology, biodiversity, conservation biology and cancer research. In summary, the package agricolae is a well established statistical toolbox based on R with a broad range of applications in design and analyses of experiments also in the wider biological community
Evaluacion de la estabilidad de resistencia de clones avanzados del CIP a la marchitez bacteriana usando diferentes variantes de Ralstonia solanacearum.
La marchitez bacteriana (MB) o pudricion parda causada por Ralstonia solanacearum es una de las enfermedades bacterianas mas destructivas en el cultivo de la papa. La resistencia de las plantas es el medio mas efectivo para controlar esta enfermedad. Sin embargo, la resistencia a la MB es a menudo superada debido a la gran variabilidad del patogeno. En el presente trabajo se evaluo la reaccion de 10 clones avanzados del CIP (seleccionados previamente por su resistencia al BV2A) contra 5 cepas correspondientes a los biovares 1, 2a, 2T y 3, de R. solanacearum bajo condiciones de invernadero. 15 plantas por clon de aproximadamente 15 cm de altura fueron inoculadas vertiendo en el suelo una suspension de 150 ml de la bacteria para obtener una concentracion final de 10 7 ufc/g suelo. Las variedades de papa Revolucion y CIP -01149 fueron utilizadas como control susceptible y moderadamente resistente, respectivamente. Las evaluaciones de la presencia de los sintomas de marchitez se realizaron semanalmente hasta 10 dias antes de la cosecha de los tuberculos. En plantas sin sintomas, los tallos y tuberculos fueron analizados mediante ELISA-NCM post-enriquecimiento para detectar infeccion latente. El analisis estadistico del porcentaje de plantas infectadas muestra diferencias significativas entre clones y cepas de R. solanacearum. No se observo resistencia completa (0% de infeccion) en ninguno de los clones evaluados a todas las cepas -de R. solanacearum. Sin embargo, el clon 394895.7 fue el mas resistente, mostrando un maximo de 13 % de infeccion cuando fue inoculado con la cepa mas virulenta (CIP-204). La resistencia a todas las cepas de R. solanacearum detectada en el clon 394895.7 muestra su alto potencial como una fuentes genetica de la resistencia a la marchitez bacterian
Yield and physiological response of potatoes indicate different strategies to cope with drought stress and nitrogen fertilization.
Drought and Freezing Vulnerability of the Isolated Hybrid Aspen \u3cem\u3ePopulus x smithii\u3c/em\u3e Relative to Its Parental Species, \u3cem\u3eP. tremuloides\u3c/em\u3e and \u3cem\u3eP. grandidentata\u3c/em\u3e
Aim
We assessed the vulnerability of an isolated, relictual Pleistocene hybrid aspen population of conservation interest (Populus x. smithii ) and the nearest populations of its parent species (Populus grandidentata and Populus tremuloides ) to springtime post‐bud break freezing and growing season drought stress. Response to these stressors in the three taxa was compared in terms of avoidance and tolerance. Location
North American Midwest; USA. Methods
Unique genets from the hybrid Niobrara River population and from the two parental populations were propagated in a common garden from rhizome cuttings. We tracked their phenology before and after bud break and measured their vulnerability to freezing (stem electrolyte leakage and leaf chlorophyll fluorescence) and to drought (stem hydraulic conductance, leaf osmotic potential, stomatal pore index, and gas exchange). Results
Populus grandidentata was slower to leaf out, showed lower vulnerability to stem freezing and drought‐induced cavitation, but exhibited a lower capacity to tolerate drought stress through leaf resistance traits compared to P. tremuloides . Hybrids were similar to P. grandidentata in their overwintering strategy, exhibiting later bud break, and in their higher resistance to stem freezing damage, but they were more similar to P. tremuloides in their higher vulnerability to drought‐induced cavitation. The hybrids shared various leaf‐level gas exchange traits with both parents. All aspens showed limited loss of leaf photosynthetic function following moderate freezing. Main Conclusions
The Niobrara River hybrid population is vulnerable to drought due to its combination of inherited drought avoidance and tolerance traits. As climate changes, P. x smithii will likely suffer from increased drought stress, while being unaffected by frost during warmer springs. The two parental species contrast in their survival mechanisms in response to climatic stress, with P. tremuloides tending toward freezing tolerance but drought avoidance and P. grandidentata tending toward freezing avoidance and drought tolerance
Metodologías de evaluación estándar y manejo de datos de clones avanzados de papa. Modulo 2: Evaluación del rendimiento de tubérculos sanos de clones avanzados de papa, guía para colaboradores internacionales.
Production properties of K*(892) vector mesons and their spin alignment as measured in the NOMAD experiment
First measurements of K*(892) mesons production properties and their spin
alignment in nu_mu charged current (CC) and neutral current (NC) interactions
are presented. The analysis of the full data sample of the NOMAD experiment is
performed in different kinematic regions. For K*+ and K*- mesons produced in
nu_mu CC interactions and decaying into K0 pi+/- we have found the following
yields per event: (2.6 +/- 0.2 (stat.) +/- 0.2 (syst.))% and (1.6 +/- 0.1
(stat.) +/- 0.1 (syst.))% respectively, while for the K*+ and K*- mesons
produced in nu NC interactions the corresponding yields per event are: (2.5 +/-
0.3 (stat.) +/- 0.3 (syst.))% and (1.0 +/- 0.3 (stat.) +/- 0.2 (syst.))%. The
results obtained for the rho00 parameter, 0.40 +/- 0.06 (stat) +/- 0.03 (syst)
and 0.28 +/- 0.07 (stat) +/- 0.03 (syst) for K*+ and K*- produced in nu_mu CC
interactions, are compared to theoretical predictions tuned on LEP measurements
in e+e- annihilation at the Z0 pole. For K*+ mesons produced in nu NC
interactions the measured rho00 parameter is 0.66 +/- 0.10 (stat) +/- 0.05
(syst).Comment: 20 p
Final NOMAD results on nu_mu->nu_tau and nu_e->nu_tau oscillations including a new search for nu_tau appearance using hadronic tau decays
Results from the nu_tau appearance search in a neutrino beam using the full
NOMAD data sample are reported. A new analysis unifies all the hadronic tau
decays, significantly improving the overall sensitivity of the experiment to
oscillations. The "blind analysis" of all topologies yields no evidence for an
oscillation signal. In the two-family oscillation scenario, this sets a 90%
C.L. allowed region in the sin^2(2theta)-Delta m^2 plane which includes
sin^2(2theta)<3.3 x 10^{-4} at large Delta m^2 and Delta m^2 < 0.7 eV^2/c^4 at
sin^2(2theta)=1. The corresponding contour in the nu_e->nu_tau oscillation
hypothesis results in sin^2(2theta)<1.5 x 10^{-2} at large Delta m^2 and Delta
m^2 < 5.9 eV^2/c^4 at sin^2(2theta)=1. We also derive limits on effective
couplings of the tau lepton to nu_mu or nu_e.Comment: 46 pages, 16 figures, Latex, to appear on Nucl. Phys.
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