Evaluación de líneas de maíz flint colorado por aptitud combinatoria

Abstract

1GRACIELA NESTARES 2 , EDITH FRUTOS 3 y GUILLERMO EYHÉRABIDE 4 RESUMEN -En las especies que exhiben heterosis, el conocimiento de la aptitud combinatoria del germoplasma en cruzamientos con probadores genéticamente divergentes permite su clasificación según grupos heteróticos. El objetivo del presente trabajo fue evaluar 48 líneas de maíz (Zea mays) flint colorado en base a su comportamiento en cruzamientos de prueba con los probadores dentados sB73 y sMo17 del patrón heterótico Reid x Lancaster y con los probadores flint HP3 y P5L2 del patrón heterótico local HP3 x P5L2 en cuatro ambientes durante la campaña 1991/92. Se realizaron los análisis de variancia por ambiente y en forma combinada a través de ambientes para: rendimiento en grano, altura de inserción de espiga, días a floración masculina, número de hileras de grano, largo y diámetro de espiga, peso de 300 granos y peso hectolítrico. Se estimaron los coeficientes de correlación de Spearman para el rendimiento de los cruzamientos de prueba con cada probador. Las interacciones línea por probador fueron altamente significativas para la mayoría de las variables y no hubo correlación entre el ordenamiento de mérito de las líneas basado en su comportamiento en cruzamientos de prueba. Ello refleja la importancia de efectos génicos no aditivos y la capacidad discriminatoria de estos probadores en cruzamientos con las líneas evaluadas.Términos para índice: Zea mays, probadores, cruzamientos de prueba. COMBINING ABILITY EVALUATION IN ORANGE FLINT LINES OF MAIZEABSTRACT -In species that show heterosis, information about combining ability with genetically divergent testers is useful to classify the germplasm in heterotic groups. The objective of this study was to evaluate 48 orange flint maize (Zea mays) lines for their combining ability with the testers: sB73 and sMo17 from the Reid x Lancaster pattern and with the flint testers HP3 and P5L2 from the local orange flint pattern during the 1991/92 season at four environments. Analyses of variance were computed for each environment separately and combined across environments for: seed yield, ear height, days to 50% silk, number of ear rows, ear length and diameter, 300 kernels weight, and test weight. Spearman correlation coefficients for grain yield of testcrosses with each tester were computed. Line x tester interactions were highly significant for the majority of the traits and there was no correlation between the merit order of lines based on testcrosses performance. These results suggest the importance of non-additive effects and the ability of the testers to rank the lines.

Analysis of genetic diversity in Argentinian heterotic maize populations using molecular markers

“…From the 21 loci analyzed, 12 showed significant p-values, with respect to the test of genic differentiation among the four heterotic populations previously determined by Nestares et al (1999). Although the maximun likelihood clustering (Program STRUCTURE) showed a better behavior than traditional methods based on genetic distance (UPGMA-modified Roger's distance), in general a significant agreement was not observed between the molecular data and the cluster based on the topcross method.…”

“…The most used methods for establishment of heterotic patterns are top cross tests (de Azevedo Duarte et al, 2003;Nestares et al, 1999) and the dialellic analysis, not implemented very often due to the high number of crossings required (Pinto et al, 2001). It has been stated that microsatellite markers might complement or allow for the replacement of top cross tests in establishing new heterotic patterns.…”

“…This research involved 26 lines selected out of 48, previously arranged in four heterotic groups by test cross with four synthetic populations (Nestares et al, 1999;Eyérabide et al, 2006). The four synthetic populations used as testers were: sB73 and sMo17 from the Reid × Lancaster pattern and HP3 and P5L2 from the local flint pattern (Nestares et al, 1999).…”

“…The four synthetic populations used as testers were: sB73 and sMo17 from the Reid × Lancaster pattern and HP3 and P5L2 from the local flint pattern (Nestares et al, 1999). All lines, except B73, evaluated in this work (Iowa Stiff Stalk Synthetic) were developed by the Argentinean INTA (Instituto Nacional de Tecnología Agropecuaria) from different origins of Cristalino Colorado maize, mainly local races (Table 1).…”

“…The main parameters of the program (and number of replications) were both determined in 1,000,000. A script in R language was implemented to determine the best agreement level between the clusters based on molecular data obtained in this work and the cluster based on the top crosses made by Nestares et al (1999). The program allowed us to compare the number of individuals coinciding in the four groups determined on the basis of the molecular information and in the four groups determined based on the topcross method.…”