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In Mexico, conventional insecticides are the main tools used to manage the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), in maize, Zea mays L. This scenario results in the need to continually assess the biological efficacy of insecticides used to combat this pest. In this study, we evaluated the efficacy of insecticides with different modes of action in diverse locations under different levels of S. frugiperda larval infestation. The insecticides evaluated decreased larval density per plant to levels below the recommended economic threshold (ET) of 2.0 larvae per 10 plants (0.2/plant), resulting in decreased levels of damage to the plant whorl. When applied at infestation levels below the ET, larval numbers remained below the ET for at least 7–14 d after application. In contrast, when applied with infestation levels above the recommended ET, the performance of some insecticides in terms of effectively reducing larval density decreased. We, however, found that Coragen® (chlorantraniliprole; FMC Agroquímica de México), Clavis® (thiodicarb + triflumuron; Bayer de México), and Pleo® 50 EC (pyridalyl; Valent de México) can be used under these conditions to provide adequate protection up to 21 d after application. The information obtained in our experiments confirms the need to adjust the current ET depending on the type of compound to be used, since the insecticides used performed more efficiently and for a long time at densities lower than 2.0 larvae per 10 plants.

Turcicum leaf blight (TLB) is a common foliar disease of maize in Mexico that is caused by the fungal pathogen Exserohilum turcicum. The most effective management strategy against TLB is monogenic race-specific resistance. Among the 140 E. turcicum isolates from symptomatic leaves collected from maize fields in Mexico, 100 were obtained from tropical (Veracruz) and temperate areas (Estado de México) between 2010 and 2019, and 40 isolates were obtained from tropical (Sinaloa, Tamaulipas, Veracruz, and Chiapas), subtropical (Nayarit, Jalisco, and Guanajuato), and temperate areas (Estado de Mexico, Hidalgo, and Puebla) collected in 2019. All the isolates caused TLB symptoms on the positive control (ht4), showing that they were all pathogenic. Six physiological races of E. turcicum (2, 3, 23, 3N, 23N, and 123N) were identified based on resistant or susceptible responses displayed by five maize differential genotypes (A619Ht1, A619Ht2, A619Ht3, B68HtN, and A619ht4). The most common was race 23, accounting for 68% of the isolates, followed by races 23N, 123N, 3, 2, and 3N at 15, 8, 6, 2, and 1%, respectively. Race 123N was able to infect the greatest number of maize differential genotypes used in the study. Race 123N was detected in Sinaloa and Estado de México. Race 3 was detected in Nayarit and Jalisco. Race 2 was detected in Jalisco, Estado de México, and Veracruz, and race 3N was detected in Tamaulipas. Race 23 was equally dominant in the tropical, subtropical, and temperate regions, while race 123N was more common in the tropical environment, and race 23N was more common in the tropical and temperate environments. There was no evidence for shifts in the races between 2010 and 2019.

La mancha foliar del trigo causada por Zymoseptoria tritici es una enfermedad devastadora en el cultivo de trigo a nivel internacional. El control químico y el uso de variedades resistentes son las principales estrategias de control. El Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT), cuenta con líneas de trigo con resistencia cuantitativa a la enfermedad por lo que el objetivo fue hacer un mapeo de loci para un carácter cuantitativo (QTL) asociados con la resistencia genética a la mancha foliar en la línea élite Mutus#1 (resistente), en una población de 275 líneas endogámicas recombinantes (LER) derivadas de la cruza de Mutus#1 con la línea élite Huirivis#1 (susceptible). En 2018 y 2019, en la estación del CIMMYT-Toluca se estableció un experimento en campo bajo un diseño experimental Alpha Lattice. Se generó una epidemia artificial con Z. tritici y se calculó el área bajo la curva del progreso de la enfermedad (ABCPE). Las 275 LER y los progenitores se secuenciaron utilizando la plataforma DArTSeq. Los mapas de ligamiento se construyeron con el programa IciMapping empleando la información del fenotipo y genotipo. Se identificaron cinco QTL de efecto menor, tres ubicados en los cromosomas 1B, 4A y 4B y dos en el cromosoma 5B, los cuales explicaron menos de síntomas y producción de picnidios en planta adulta portados por Mutus#1, pueden utilizarse con otros genes de resistencia o QTL para reducir la selección de nuevas cepas patogénicas de Z. tritici.

Una de las principales plagas en el cultivo de tomate (Solanum lycopersicum L.) es Bemisia tabaci (Genn.), la cual transmite virus fitopatógenos responsables de daños fisiológicos severos y pérdidas de rentabilidad del cultivo. La protección de la planta contra vectores virales en las primeras semanas después del trasplante es fundamental para asegurar la producción. El experimento se realizó en invernadero y se repitió dos veces, se utilizaron plántulas de tomate cultivar Rio Grande para evaluar la efectividad residual de cinco insecticidas sintéticos, cuatro botánicos y un aceite mineral. Se evaluó la densidad de huevos de B. tabaci y el porcentaje de efectividad, a los 0, 5 y 10 días después de la aplicación (DDA) con insecticida. El tratamiento órgano-sintético con la mejor efectividad fue Sivanto®Prime (Flupyradifurone) en aplicaciones foliares y en el suelo; dentro de los productos naturales, el mejor tratamiento fue PHC® Neem® (Azadiractina) en aplicaciones foliares; ambos presentaron efectividad, de 99.96-88.47% y 65.87-43.5%, respectivamente, a los 0, 5 y 10 DDA en los dos ensayos. La información de la residualidad y la efectividad de los insecticidas evaluados contribuirá para complementar el óptimo manejo de B. tabaci.

Determining the stability and consistency of grain yield performance requires accurate evaluation of genotypes in different environments. In Mexico, annual national spring wheat irrigated trials are conducted to assess elite bread and durum wheat performance in different testing environments (TEs) in the main wheat-growing areas. These trials provide data supporting release of new cultivars and aim to also address Mexican wheat value chain grain needs. In this study we analyzed 30 bread and durum wheat trial results from the 2012/13 and 2013/14 growing cycles conducted across TEs in northwest, north and central Mexico. Environmental variability (location, sowing timing, and irrigation schemes) across the national spring wheat irrigated trials enabled genotype by environment interaction to be effectively evaluated. We identified genotypes with high and stable grain yield across TEs of the wheat-growing areas of Mexico. The bread cultivars Bacorehuis F2015 and Borlaug100 F2014, and the durum cultivars Barobampo C2015, CONASIST C2015 and Anatoly C2011 were high yielding and gave stable performance in most of the TEs. This analysis demonstrates the utility of multi-year, multi-environment testing and analysis to identify improved wheat cultivars to meet wheat production demand in Mexico.

Embrapa has led breeding programs for irrigated and upland rice (Oryza sativa L.) since 1977, generating a large amount of pedigree and phenotypic data. However, there were no systematic standards for data recording nor long-term data preservation and reuse strategies. With the new aim of making data reuse practical, we recovered all data available and structured it into the Embrapa Rice Breeding Dataset (ERBD). In its current version, the ERBD includes 20,504 crosses involving 9,974 parents, the pedigrees of most of the 4,532 inbred lines that took part in advanced field trials, and phenotypic data from 2,711 field trials (1,118 irrigated, 1,593 upland trials), representing 226,458 field plots. Those trials were conducted over 38 years (1982-2019), in 247 locations, in latitudes ranging from 3°N to 33°S. Phenotypic traits included grain yield, days to flowering, plant height, canopy lodging, and five important fungal diseases: leaf blast, panicle blast, brown spot, leaf scald, and grain discoloration. The total number of data points surpasses 1.27 million. Descriptive statistics were computed over the dataset, split by cropping systems (irrigated or upland). The mean heritability of grain yield was high for both systems, at around .7, whereas the mean coefficient of variation was 13.9% for irrigated trials and 18.7% for upland trials. The ERBD offers the possibility of conducting studies on different aspects of rice breeding and genetics, including genetic gain, G×E analysis, genome-wide association studies and genomic prediction. Made available in DSpace on 2021-11-30T12:00:26Z (GMT). No. of bitstreams: 1 cropscience-2021.pdf: 1682169 bytes, checksum: e47084fb3060926dd37ca8419b8936da (MD5) Previous issue date: 2021

Resumen En la literatura científica actual se discute ampliamente acerca de la predicción de propiedades edáficas mediante información espectral. El objetivo de esta revisión fue encontrar algoritmos con el mayor potencial predictivo para las propiedades fisicoquímicas del suelo, basados en información espectral capturada con diferentes instrumentos. Se realizó una revisión sistemática en la cual se encontraron 121 artículos de los cuales se eligieron 19, que cumplieran con un coeficiente de determinación mayor a 0,80 o una raíz del error cuadrado medio cercana a 0. Se determinó que el rango espectral más utilizado corresponde al rango desde 350 hasta 2500 nm; los algoritmos mínimos cuadrados parciales, máquina de soporte vectorial y máquina de soporte vectorial ajustado son adecuadas para predecir pH, materia orgánica y carbono orgánico. Además, la regresión lineal solo es efectiva para predecir el carbonato de calcio, materia orgánica, humedad y contenido de agua mediante bandas individuales. Abstract The prediction of soil properties through spectral information is widely discussed in the current scientific literature. The objective of this review was to find algorithms with the highest predictive potential for soil physicochemical properties based on spectral information captured with different instruments. A systematic review was carried out in which 121 articles were found, and 19 of them were chosen which met a determination coefficient greater than 0.80 or a root mean square error close to 0. It was determined that the most used spectral range corresponds to the range from 350 to 2500 nm; the partial least squares, support vector machine, and adjusted support vector machine algorithms are suitable for predicting pH, organic matter, and organic carbon. Furthermore, linear regression is only effective in predicting calcium carbonate, organic matter, moisture, and water content using individual bands.

México es el séptimo productor de jamaica (Hibiscus sabdariffa), y el estado de Guerrero concentra más del 70 % de la producción nacional. El cultivo presenta limitantes fitosanitarias importantes, destacando la “pata prieta” asociada a un complejo de patógenos (Fusarium oxysporum y Phytophthora parasitica), con pérdidas de hasta 100 % en áreas sin manejo fitosanitario. Debido a la naturaleza del consumo del producto final, es necesaria la implementación de estrategias ecológicas de manejo de la enfermedad. El objetivo del estudio fue cuantificar la actividad de quitinasas y glucanasas de aislados Trichoderma spp., y evaluar su efecto inhibitorio in vitro sobre F. oxysporum y P. parasitica. Se evaluaron las cepas Ta10, Ta11, Ta6 y Ta9 de T. asperellum y Ti14 de T. inhamatum provenientes de suelos cultivados con jamaica y alta incidencia de los patógenos. Los niveles de quitinasas y glucanasas en todos los aislados de Trichoderma spp. fueron significativos (P£0,05); la cepa Ta9 mostró la mayor actividad específica de quitinasas, y la cepa Ti14 la mayor de glucanasas. Todos los filtrados provenientes de los diferentes aislados de Trichoderma spp. generaron una inhibición sustancial del crecimiento micelial de F. oxysporum y P. parasitica. De manera consistente, la cepa Ta9 alcanzó porcentajes de inhibición mayores al 90 % en ambos ensayos. Se detectó correlación significativa entre la actividad enzimática y la inhibición del crecimiento de los aislados de Trichoderma spp. sobre los agentes patógenos.

META-R (multi-environment trial analysis in R) is a suite of R scripts linked by a graphical user interface (GUI) designed in Java language. The objective of META-R is to accurately analyze multi-environment plant breeding trials (METs) by fitting mixed and fixed linear models from experimental designs such as the randomized complete block design (RCBD) and the alpha-lattice/lattice designs. META-R simultaneously estimates the best linear and unbiased estimators (BLUEs) and the best linear and unbiased predictors (BLUPs). Additionally, it computes the variance-covariance parameters, as well as some statistical and genetic parameters such as the least significant difference (LSD) at 5% significance, the coefficient of variation in percentage (CV), the genetic variance, and the broad-sense heritability. These parameters are very important in the selection of top performing genotypes in plant breeding. META-R also computes the phenotypic and genetic correlations among environments and between traits, as well as their statistical significance. The genetic correlations between environments or traits can be visualized in a biplot graph or a tree diagram (dendrogram). Genetic correlations are very important for identifying environments with similar behavior or making indirect selection and identifying the most highly associated traits. META-R performs multi-environment analyses by using the residual maximum likelihood (REML) method; these analyses can be done by environment, across environments by grouping factors (stress conditions, nitrogen content, etc.) and across environments; the analyses across environments can be done with a pre-defined degree of heritability.

The aphid Melanaphis sacchari/sorghi is considered the most important pest of sorghum cultivation in Mexico. It can cause losses in production of up to 100%. This research was conducted at the Universidad Autonoma Chapingo during 2018 and 2019 with the objective of determining the relationship between chemical fertilization in sorghum and M. sacchari/sorghi (Hemiptera: Aphididae) populations. Different levels of nitrogen (125, 250 and 500 kg ha-1), phosphorus (19.5, 39 and 78 kg ha-1) and potassium (210 and 420 kg ha-1) were supplied to sorghum plants planted in polyethylene pots with a capacity of 6 L under greenhouse conditions. The plants were infested with a total of 15 third-instar nymphs within 60 days of crop emergence. A total of 6 samplings were carried out at 7 day intervals, starting at 7 d after the infestation. Quantifications of total soluble proteins, total soluble sugars, reducing sugars, and levels of nitrogen, phosphorus, potassium and magnesium in leaf tissue were also performed. We observed that higher doses of nitrogen and phosphorus increased the aphid population, while increasing the potassium dose considerably decreased the aphid population. We also found a positive correlation between the aphid population and the total soluble protein concentrations, reducing sugars and nitrogen levels, while the correlation was negative with potassium levels in leaves.

Se realizaron aplicaciones de los inductores de resistencia: Messenger gold®, Virus Stop®, Actigard®, Virablock®, Kendal®, fosfito de potasio, Stymulus® Maxx, Bacillus subtilis y MC Cream® en el año 2018, de forma individual y combinados en secuencias, para evaluar su efecto sobre la concentración viral (densidad óptica), crecimiento, longitud de raíz, severidad, peso seco total, número y peso de frutos en el cultivo de jitomate (Solanum lycopersicum L.) infectado con Tobacco mosaic virus (TMV). La secuencia de los inductores Messenger gold®+ Messenger gold®+ MC Cream® + MC Cream® redujeron la concentración de TMV a los 38 días después de la inoculación, determinada mediante DAS-ELISA. La aspersión de Virablock® obtuvo la mayor altura promedio. Las plantas tratadas con la secuencia Virus Stop® + Virus Stop® + fosfito de potasio + fosfito de potasio obtuvieron la menor severidad promedio. Las plantas asperjadas con Messenger gold® + Messenger gold® + MC Cream® + MC Cream® registraron la mayor longitud de raíz, mayor peso seco total y el segundo mayor número y peso promedio de frutos que no mostraron síntomas de TMV en frutos.

Los miembros del género begomovirus se transmiten por Bemisia tabaci y causan severas pérdidas en las cucurbitáceas. Los objetivos del estudio fueron: i) investigar la etiología de la enfermedad provocada por el virus de la hoja rizada de la calabaza; ii) conocer la dinámica de población del vector, comparar la efectividad de trampas amarillas pegajosas contra charolas amarillas y determinar el efecto del sitio de ubicación de las trampas, en el monitoreo de B. tabaci durante el ciclo de desarrollo del cultivo; y iii) estudiar la distribución espacio-temporal y severidad de virosis en calabaza. El estudio se realizó en la estación experimental del Colegio Superior Agropecuario del estado de Guerrero, ubicado en el Valle de Cocula. Se realizó la extracción del ADN a partir de hojas de calabaza (Cucurbita pepo) var. Grey Zucchini con síntomas de virosis. El PCR se llevó a cabo en cinco muestras con los oligonucleótidos genéricos para begomovirus, se secuenciaron dos productos de PCR y se generó un árbol filogenético. Se realizó la prueba de transmisión del virus en calabaza, en condiciones controladas. La dinámica poblacional de B. tabaci se determinó utilizando trampas amarillas pegajosas y charolas amarillas. A partir, de la sintomatología, se obtuvo el porcentaje de severidad y el área bajo la curva del progreso de la enfermedad (ABCPE). El análisis de PCR, secuenciación y filogenia, confirmaron la presencia del virus SLCV (KX620945.1-DAAV-1) en calabaza. Se comprobó que B. tabaci transmite a SLCV que reduce el crecimiento de la planta. La trampa pegajosa y fecha de muestreo influyen en la fluctuación poblacional de B. tabaci. La incidencia de B. tabaci y severidad de SLCV se manifestaron en todas las etapas fenológicas del cultivo y se relacionaron con el nivel de temperatura.

Background: recently there has been concern for the monitoring of ambrosial complexes in Mexico that consist of a symbiotic relationship between a beetle and fungi, where the female invades a wide variety of species making galleries in the bark and wood, in which beetles reproduce and grow the fungi to feed the colony, these fungi can be a phytopathogen that can cause serious damage in the infected trees. The proximity of Raffaelea lauricola now present in Texas and the presence of Fusarium euwallacea in the north of Mexico; fungi that have caused great losses in the United States, put in risk the avocado production zones in Mexico. Consequently, the report of new fungi related to ambrosial complexes is of great importance. Objective: to carry out pathogenicity tests of fungi related to ambrosial complexes in avocado ‘Hass’. Methodology: Isolates of Raffaelea brunnea, Ceratocystiopsis sp. (pre-identified) and Fusarium sp., from avocado trees parasitized with ambrosial beetles from the state of Michoacán and an unidentified fungus from Chiapas (Mexico) were used. Artificial inoculations with the fungi were carried out by wounds in mature stem and shoots of the growth of the year (young) of ‘Hass’ plants, and the symptoms and the progress of the damage within the stem were evaluated. Three of the isolates underwent a molecular identification analysis with the complete region of the ITS internal transcript space. Results: the fungus Ceratocystiopsis sp. was identified as Ophiostoma sp. and Fusarium sp. such as Fusarium solani, both isolated from Michoacán. While the Chiapas fungus was identified belonging to the genus Fusarium. After inoculation, R. brunnea and Fusarium sp. stood out in pathogenicity, with greater advancement within the stem and damage that in some cases reached the pith tissue, showing leaf wilting and reddish-brown staining inside the stem. These two fungi showed differential damage progression behavior according to the type of maturity of the tissue, where Fusarium sp. advanced more in the young tissue and R. brunnea in the mature one. Implications: it is proposed to consider that the study was only carried out in ‘Hass’, thus this may be an important factor, since probably if the fungi were inoculated in more varieties, differences in behavior of the advance in damage of these could be found. Conclusions: all the fungi showed to be pathogenic with variation in severity. In terms of Raffaelea brunnea, a peculiar behavior was found in the severity of internal and external damage, in which external symptoms may or may not occur, strictly in ‘Hass’ avocado plants 30 days after inoculation.

The main objective of a plant breeding program is to deliver superior germplasm for farmers in a defined set of environments, or a target population of environments (TPE). Historically, CIMMYT has characterized the environments in which the developed germplasm will be grown. The main factors that determine when and where a wheat variety can be grown are flowering time, water availability and the incidence of pests and diseases. A TPE consists of many (population) environments and future years or seasons, that share common variation in the farmers’ fields, it can also be seen as a variable group of future production environments. TPEs can be characterized by climatic, soil and hydrological features, as well as socioeconomic aspects. Whereas the selection environments (SE) are the environments where the breeder does the selection of the lines. The SE are identified for predicting the performance in the TPE, but the SE may not belong to the TPE. The utilization of advanced statistical methods allows the identification of GEI to obtain higher precision when estimating the genetic effects. Multi-environmental testing (MET) is a fundamental strategy for CIMMYT to develop stable high grain yielding germplasm in countries with developing economies. An adequate MET strategy allows the evaluation of germplasm in stress hotspots and the identification of representative and correlated sites; thus, breeders can make better and targeted decisions in terms of crossing, selection and logistic operations.

Multivariate analysis is preferred over univariate analysis in plant breeding studies because it can exploit correlated traits and environments, whereas Bayesian analysis provides a natural way to incorporate prior knowledge and inferences that are conditional on the observed data. The objective of this paper is to show how to use multivariate Bayesian analysis for estimating random effects of genotype x environment and genotype x environment x trait combinations, and for computing genotypic and phenotypic correlations among traits and environments. Data were collected from on-farm trials conducted by the International Maize and Wheat Improvement Center (CIM-MYT) to evaluate bread and durum wheat lines in the Yaqui Valley of southern Sonora, Mexico, during three crop seasons (2012, 2013, and 2015). The Bayesian multi-trait and multi-environment model with Gibbs sampler provides an analytic solution that can be used as an alternative for analyzing on-farm multiple-trait and multiple-environment data because it allows making parsimonious, precise and simultaneous estimations of random effects, genetic correlations (of traits and environments) and residual correlations of traits. The multivariate Bayesian model successfully fitted three of the four data sets (2012, 2015, and combined cropping seasons), but did not fit well the data of crop season 2013. For three out of five traits under study in this crop season, the correlations between the observed and predicted phenotypic values were lower than 0.6, suggesting that the predicted values were not very close to the observed values.

La fusariosis de la espiga por Fusarium graminearum es una enfermedad que afecta el rendimiento y la calidad sanitaria del grano de cebada. Entre las medidas de control se encuentra el uso de variedades resistentes por lo que este trabajo tuvo como objetivos evaluar la resistencia a la fusariosis y a la acumulación de deoxinivalenol (DON) en 131 líneas avanzadas de cebada maltera seleccionadas por su tolerancia a roya amarilla, roya de la hoja, mancha reticulada, tizón foliar y escaldadura de la hoja, del programa de Cebada del INIFAP-CEVAMEX. Durante tres años las líneas avanzadas 30, 47, 65 y 123, así como las líneas 73, 91 y 96, de seis y dos hileras de grano, respectivamente, registraron síntomas muy bajos de fusariosis en respuesta a la inoculación con F. graminearum. Aunque la severidad de la enfermedad no se relacionó (r= 0.5682) con la acumulación de DON, estas líneas registraron muy baja o nula producción de toxina. La información generada en este estudio es relevante ya que indica que estas líneas son resistentes a la enfermedad y tienen potencial para utilizarse como fuentes de resistencia en un programa de cruzamientos en cebada maltera que incluya en el conjunto de enfermedades a la fusariosis de la espiga.

El consumo del insecto comestible Comadia redtenbacheri (Hammerschmidt) conocido como gusano rojo del maguey, aumento en los ultimos anos, lo que ha llevado a una colecta excesiva de poblaciones silvestres de esta especie. La presente investigacion propone metodos para la infestacion inducida de plantas de Agave salmiana en macetas con larvas de ∼0.12 g y ≥ 0.30 g de peso promedio a densidades de 20, 30, y 40 por planta, asi como adultos recien emergidos en las proporciones hembra-macho 1:1, 1:2, y 2:1, ademas de plantas en suelo con larvas ≥0.30 g a densidades de 30, 60, 90, y 120. Las larvas de mayor peso en macetas, a densidades de 30 y 40 individuos por planta, presentaron mas pupas y emergencia de adultos. Hembras-machos liberados a 1:2 tuvieron un promedio de 12 larvas por planta y 75% de plantas infestadas. Con las larvas liberadas en el suelo a una densidad de 60, se logro el establecimiento de una segunda generacion con 72% de plantas infestadas y 14.5% de dano promedio al interior del tallo. Los resultados obtenidos pueden servir de base para programas de produccion o restablecimiento de poblaciones de gusano rojo.

El carbón de la espiga del maíz (Sporisorium reilianum f. sp. zeae) es una enfermedad que se caracteriza porque el patógeno remplaza las inflorescencias por soros llenos de teliosporas. El objetivo de este estudio fue investigar la respuesta en campo de 55 poblaciones de maíz nativo a la infección por S. reilianum. Las poblaciones de maíz se colectaron en los estados de Guerrero (13), Oaxaca (13), Puebla (seis), Tlaxcala (12) y Estado de México (11). La semilla fue inoculada con teliosporas del patógeno, usando grenetina como adherente. El híbrido Az 41801 se utilizó como testigo. Las poblaciones fueron evaluadas en Mixquiahuala, Hidalgo, en los ciclos 2015 y 2016. La incidencia de la enfermedad se registró mediante la observación directa de signos y síntomas en las inflorescencias. La incidencia máxima de la enfermedad en las poblaciones de maíz fue de 28.8% y 22.2% en la primera y segunda evaluación, respectivamente, mientras que el testigo (Az 41801) presentó una incidencia de 70.7% y 42.3%. Considerando el origen geográfico, los maíces del Estado de México y Tlaxcala presentaron una menor incidencia de la enfermedad respecto al resto de las poblaciones, lo que indica la presencia de genes de resistencia a la enfermedad.

Este artículo realiza un abordaje histórico, social y político de la situación en Latinoamérica y su proceso de construcción democrático. En este sentido, presta especial atención en la vinculación entre poder hegemónico y constitucionalismo en los casos de Colombia y Paraguay. Para ello, realiza un análisis histórico-comparativo entre ambos países, que permea en el bipartidismo y el autoritarismo, con el objetivo de determinar las propuestas que traen ambos procesos constitucionales dentro del contexto de democracia y su relación con los poderes hegemónicos.

Phenotypic-genotypic covariance and correlation have been useful in crop and animal breeding programs. In the study of diversity of natural populations and different cultivars of plants that are examined based on statistical design, estimation of genotypic-phenotypic covariance through expected value of statistical designs mean square is hard and time-consuming when the number of studied traits is high. Moreover, the lack of a program in this field and manual calculations make the estimation more complicated. Therefore, in this study, one program was developed in SAS that can be used to calculate the genotypic-phenotypic covariance matrix through the first part of the program based on the expected value of applied statistical designs mean square. Then, based on the covariance matrix computed from the previous design model, their correlation matrix was calculated using the second part of the program based on the interactive matrix language (IML) of SAS. The phenotypic-genotypic covariance matrices of the 12 studied traits of rice are calculated based on this code. This program could compute phenotypic-genotypic covariance and correlation matrices based on the expected value of any statistical designs.