Rendimiento y características agronómicas de frijol de temporal en generaciones tempranas

En el programa de mejoramiento genético de frijol de la región semiárida de México la selección por rendimiento se realiza en generaciones avanzadas. El presente estudio se realizó con el objetivo de determinar en poblaciones segregantes de frijol de temporal el nivel de heterosis, heterobeltiosis y depresión endogámica de diversas caracter ísticas agronómicas. Se evaluaron cuatro poblaciones de frijol de grano negro en las generaciones F2 y F3, y siete de diferentes colores en las generaciones F3 y F4. Además, se incluyeron los progenitores de cada población. En las poblaciones de grano negro, la derivada de la cruza BAT 76 x Negro Qro. presentó en ambas generaciones los más altos rendimientos, la mayor producción de materia seca total y los más altos valores de heterosis para esas caracter ísticas, así como el mayor valor de heterobeltiosis en la generación F3. En el grupo de colores, la población derivada de la cruza 102- M x Bayo Victoria fue de las más rendidoras en las dos generaciones, presentó los más altos valores de heterosis y fue la única que mostró heterobeltiosis en ambas generaciones. Las poblaciones con alto rendimiento y heterosis en las generaciones tempranas, conservaron ambas caracter ísticas en la generacion posterior y los mejores progenitores produjeron las mejores poblaciones. Lo anterior sugiere que en frijol, es posible predecir las mejores cruzas e identificar poblaciones con alto potencial de rendimiento en generaciones tempranas

Genetic diversity analysis of common beans based on molecular markers

A core collection of the common bean (Phaseolus vulgaris L.), representing genetic diversity in the entire Mexican holding, is kept at the INIFAP (Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias, Mexico) Germplasm Bank. After evaluation, the genetic structure of this collection (200 accessions) was compared with that of landraces from the states of Oaxaca, Chiapas and Veracruz (10 genotypes from each), as well as a further 10 cultivars, by means of four amplified fragment length polymorphisms (AFLP) +3/+3 primer combinations and seven simple sequence repeats (SSR) loci, in order to define genetic diversity, variability and mutual relationships. Data underwent cluster (UPGMA) and molecular variance (AMOVA) analyses. AFLP analysis produced 530 bands (88.5% polymorphic) while SSR primers amplified 174 alleles, all polymorphic (8.2 alleles per locus). AFLP indicated that the highest genetic diversity was to be found in ten commercial-seed classes from two major groups of accessions from Central Mexico and Chiapas, which seems to be an important center of diversity in the south. A third group included genotypes from Nueva Granada, Mesoamerica, Jalisco and Durango races. Here, SSR analysis indicated a reduced number of shared haplotypes among accessions, whereas the highest genetic components of AMOVA variation were found within accessions. Genetic diversity observed in the common-bean core collection represents an important sample of the total Phaseolus genetic variability at the main Germplasm Bank of INIFAP. Molecular marker strategies could contribute to a better understanding of the genetic structure of the core collection as well as to its improvement and validation

Genetic diversity in cultivated carioca common beans based on molecular marker analysis

A wide array of molecular markers has been used to investigate the genetic diversity among common bean species. However, the best combination of markers for studying such diversity among common bean cultivars has yet to be determined. Few reports have examined the genetic diversity of the carioca bean, commercially one of the most important common beans in Brazil. In this study, we examined the usefulness of two molecular marker systems (simple sequence repeats – SSRs and amplified fragment length polymorphisms – AFLPs) for assessing the genetic diversity of carioca beans. The amount of information provided by Roger’s modified genetic distance was used to analyze SSR data and Jaccards similarity coefficient was used for AFLP data. Seventy SSRs were polymorphic and 20 AFLP primer combinations produced 635 polymorphic bands. Molecular analysis showed that carioca genotypes were quite diverse. AFLPs revealed greater genetic differentiation and variation within the carioca genotypes (Gst = 98% and Fst = 0.83, respectively) than SSRs and provided better resolution for clustering the carioca genotypes. SSRs and AFLPs were both suitable for assessing the genetic diversity of Brazilian carioca genotypes since the number of markers used in each system provided a low coefficient of variation. However, fingerprint profiles were generated faster with AFLPs, making them a better choice for assessing genetic diversity in the carioca germplasm

Allometric models for estimating aboveground biomass in tree sprouts of three dendroenergetic crops

Recurrent problems have been observed for biomass measurement in tree sprouts, mainly due to differences in patterns of biomass distribution and the bias generated by using models for mature trees. The objective of this research was to evaluate models to estimate aboveground biomass in sprouts from two-year-old stumps of Short Rotation Woody Crops (SRWC) used for energetic purposes. The study was conducted in Central Chile (Bío-Bío region) under a complete block design and four replications. Three plant species were included: Eucalyptus globulus, E. denticulata, and Acacia dealbata, established in three population densities (5,000, 10,000 and 15,000 trees per ha). Two groups of nonlinear models were used on three independent variables: root collar diameter (squared mean of two dominant stems), height (mean of two dominant stems) and number of epicormic stems. In the allometric model, the total aboveground biomass and the aboveground biomass by component were explained as the product of the mean square of the root collar diameter, mean height of the two dominant new sprouts and total number of epicormic sprouts as the predictive variable. Values of coefficient of determination (R2 ) ranged from 0.78 to 0.95 and RMSE ranged from 168 to 913 g. The species of E. globulus showed higher RMSE for biomass estimation in the all components except the branch component. The inclusion of dummy variables to identify the differences in each parameter of the models explained the seasonality of the biomass accumulation in tree sprouts at 10, 21, and 31 months of age, improving the model goodness of fit RMSE by 27%. Accurate prediction of sprouts aboveground biomass was obtained by the models only evaluating the two dominant epicormic sprouts in the stump, avoiding the need of individual sprouts evaluation or using destructive methods for biomass measurement

ADAPTABILITY OF THE FLOR DE JUNIO BEAN TYPE AT DIFFERENT ENVIRONMENTS IN MEXICO

Se determinó el rendimiento de 14 líneas y dos variedades comerciales de frijol tipo Flor de Junio en ambientes de temporal y riego del centro de México con el objetivo de identificar líneas de alto rendimiento con baja interacción genotipo x ambiente. El ensayo se estableció en 15 ambientes (combinación localidad/año) bajo un diseño experimental de Látice 4x4 con cuatro repeticiones. En los ambientes de temporal la siembra se realizó en julio después de la ocurrencia de lluvias, y en las de riego en noviembre y febrero dependiendo de la localidad; a cada combinación de localidad y año se consideró como un ambiente. Con la información del rendimiento se realizó un análisis por localidad y uno combinado para determinar la importancia de cada factor, a su vez, para determinar los efectos de la interacción genotipo x ambiente (IGA) se utilizó el modelo AMMI. En el análisis combinado el 70.4 % de la variación se debió al efecto del ambiente, seguido por el efecto de IGA con el 11.8 % y en tercer lugar se ubicó el factor genotipo. Las líneas con alto rendimiento medio fueron FJB 08061, FJB 08054 y FJB 08004, con 1800 kg ha-1, rendimiento apenas superior al de los testigos que produjeron un mayor rendimiento que la mitad de las líneas en evaluación. El rendimiento de la línea FJB 08004 fue comparativamente alto y estable. Otros genotipos mostraron adaptación específica, por lo que su utilización debe considerarse en localidades específicas. El análisis AMMI permitió detectar localidades contrastantes en el estado de Guanajuato que deberán utilizarse en la evaluación de germoplasma mejorado para obtener información confiable asociada a un menor insumo de recursos

Growth, nutrient accumulation in leaves and grain yield of super early genotypes of common bean.

There is a lack of researches that evaluate the development and nutrient accumulation in super early genotypes of common bean for the elaboration of fertilization programs. This study aimed at characterizing the development; N, P, K, Ca and Mg accumulation by leaves; grain yield; and yield components of super early genotypes of common bean. Field experiments were conducted in a randomized blocks design, with four replications. The treatments consisted of the IPR Colibri (control), CNFC 15873, CNFC 15874 and CNFC 15875 genotypes. Plants were sampled throughout the common bean development, being divided into leaves, stems and pods. After determining the dry matter, the contents of N, P, K, Ca and Mg accumulated in leaves were estimated. At harvesting, the grain yield and yield components were evaluated. The biomass accumulation in stems and leaves occurred until the flowering stage, and then it started in the pods until harvesting. The genotypes that absorbed more nitrogen and phosphorus had a higher grain yield. The average growing season of super early genotypes was 70 days (winter) and 63 days (summer). CNFC 15874 was the most productive genotype in the winter, with grain yield similar to the IPR Colibri cultivar (control). In the summer, CNFC 15873 and CNFC 15875 achieved grain yield similar to the IPR Colibri cultivar