Andrés González-Huerta

Genetic variability analysis of faba bean accessions using Inter-simple sequence repeat (ISSR) markers

Faba bean crop (Vicia faba L.) is important in Mexico, it is a legume rich in protein and its market price is higher than those of maize and bean; however, in recent years there has been a significant decline in its performance. The aim of this study was to determine the genetic variability and analyze the relationship between 39 faba bean accessions using inter simple sequence repeats (ISSR) markers. Accessions of faba bean were collected according to their best phenotypic characteristics, later they were molecularly characterized. With the obtained band registration, a binary data matrix was built to perform the corresponding statistical analysis. The utilized ISSR markers produced 142 fixed and repeatable bands, of which 134 were polymorphic. The values of resolution power (Rp), polymorphic information content (PIC), and marker index (MI), respectively indicated that primer 848 was the most efficient to analyze genetic variability with values of 12.8, 0.40, and 8.06, respectively, followed by primers 857 and ISSR2M. Genetic distances oscillated between 0.38 and 0.83, and verified the groupings observed in the dendrogram, which indicates high variability at the level of DNA among the analyzed genotypes, observing six defined groups according to UPGMA analysis. In the analysis of main components the registered groupings were determined by the origin of the gathering. The use of ISSR markers was efficient to characterize at the level of DNA the assessed bean accessions, indicating the existence of variability, the identified contrasting accessions can be utilized in genetic improvement programs aimed at solving the needs of the producers.

Spatial distribution of head smut (Sporisorium reilianum) of corn in Mexico

Knowledge about the spatial distribution of agricultural diseases is important for the elaboration of integrated pest management programs. Such knowledge allows the exact and adept development of sampling methods, control methods and risk valuation. Despite its importance, there have been few studies of the spatial distribution of head smut of corn in Mexico. This study aimed to determine the spatial distribution of this disease during the year 2007 in the State of Mexico and to establish its spatial behavior with geostatistical techniques. Five points per plot were chosen for sampling. For each sampling point, 100 plants in a single row were counted, and the plants that presented symptoms of the disease were recorded. The geostatistical analysis used this data to estimate the experimental semivariogram, which was adjusted using theoretical models (spherical, exponential, Gaussian and logarithmic), in the Variowin 2.2 program. The semivariogram was verified by the geostatistical interpolation method or kriging through the cross validation, and cluster maps were subsequently made. The disease was present in 32 locations of 31 counties in Mexico State. All the locations presented a spatial behavior aggregated to the disease. Twenty-four locations were adjusted to the spherical model, seven locations were adjusted to the exponential model, and one location was fit to the Gaussian model. Lastly, it was possible to set aggregation maps in all models

Snap bean production using sunflowers as living trellises in the central high valleys of Mexico

E. J. Morales-Rosales, O. Franco-Mora, and A. Gonzalez-Huerta. 2011. Snap bean production using sunflowers as living trellises in the central high valleys of Mexico. Cien. Inv. Agr. 38(1): 53- 63. The aim of this study was to assess growth, net assimilation rate, biomass production and pod yield in two snap bean cultivars sown in monoculture and combined with two sunflower cultivars at three localities in the State of Mexico, Mexico. The six treatments were evaluated in a 2 × 3 factorial experiment in a randomized complete block design with four replications. When F values were significant, the least significant difference test at the 5% level of significance was used. The principal component analysis was also used to study the interrelationship among the six treatments and seven variables. The results observed in the biplot indicated that the largest original variation in the data was adequately represented in the first two principal components since both accumulated 68.5%. This variability was classified into four groups: ‘Criollo’ + ‘Sunbright’ and ‘Acerado’ + ‘Victoria’ contributed to the better phenotypic expression of leaf area index, pod yield and pod length; ‘Criollo’, with best average performance for net assimilation rate, number of pods and total biomass; ‘Criollo’ + ‘Victoria’ and ‘Acerado’ + ‘Sunbright’, the former with the largest pod diameter; and ‘Acerado’, with the poorest performance in leaf area index, pod yield and pod length. Treatments ‘Criollo’ and ‘Criollo’ + ‘Sunbright’ showed the highest pod yield (7.66 and 7.70 t·ha -1 , respectively), which is attributed to both, presented the highest values of leaf area index, total biomass and numbers of pods.