Abstract
The efficiency of selection can be broadened for certain traits using estimative of genetic parameters, which are fundamental for plant breeding. The estimative of genetic parameters allows identifying the nature of the action of genes involved in the control of quantitative traits and evaluates the efficiency of different breeding strategies to obtain genetic gains. Therefore, this study aimed to verify the variability and correlation between morphological and agronomic traits in synthetic maize populations, in order to practice indirect selection. Thirteen populations were evaluated in field experiments at Jaboticabal- SP and Campo Alegre de Goias-GO, using randomized block design, for lodging (LOD), culm breakage (CB), plant height (PH), ear height (EH) and grain yield (GY). The 13 populations were also sown in 1 kg-plastic bags under black shade cloth, using a randomized complete block design with nine replications, for evaluation of the morphological traits: main root length (MRL), root fresh matter (RFM), root dry matter (RDM), average root diameter (ARD), root surface area (RSA), root tissue density (RTD) and shoots dry matter (SDM). The trait GY exhibited genetic variability enough to be effective if used for selection. The selection on the morphological traits is indicated on RDM, due to the ease in obtaining data and its accuracy, high correlation with all morphological traits and association with GY. The simultaneous selection based on RFM and RDM, for gains in GY, can be performed. The highest direct effect on GY was identified in LOD and CB, being indicated for indirect selection.
Highlights
High yields are directly related to the biggest depths explored by the plant root system (KOFFLER, 1986), which makes information about the root system of maize genotypes and their possible relationship with the shoots, of great interest in maize breeding programs
The efficiency of selection can be broadened for certain trait using estimates of genetic parameters, which are fundamental in the plant breeding, since they allow identifying the nature of the action of genes involved in the control of quantitative traits and evaluate the efficiency of different breeding strategies to obtain genetic gains (CRUZ; CARNEIRO, 2006)
The individual analysis of variance presented significant differences (p0.01) among populations regarding the agronomic traits of LOD, culm breakage (CB), plant height (PH), ear height (EH) and grain yield (GY), and morphological traits of root fresh matter (RFM), root dry matter (RDM), root surface area (RSA), main root length (MRL), root tissue density (RTD) and shoots dry matter (SDM) (Table 1)
Summary
High yields are directly related to the biggest depths explored by the plant root system (KOFFLER, 1986), which makes information about the root system of maize genotypes and their possible relationship with the shoots, of great interest in maize breeding programs. The use of methods for indirect selection of root traits or early evaluation, i.e., before flowering, is interesting. These methods accelerate the process of selection, immediately discarding undesirable genotypes, which enables focus resources on those potentially superiors (FRITSCHE-NETO et al, 2010). The efficiency of selection can be broadened for certain trait using estimates of genetic parameters, which are fundamental in the plant breeding, since they allow identifying the nature of the action of genes involved in the control of quantitative traits and evaluate the efficiency of different breeding strategies to obtain genetic gains (CRUZ; CARNEIRO, 2006). The estimates of genetic parameters as variances, coefficients of variation, heritability, genotypic, phenotypic and environmental correlations, allow knowing the magnitude of the genetic variability of a population, and the selection gains
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