Abstract
The aim of this study was to investigate the genetic variability among early-maturing and extremely early-maturing corn cultivars in relation to grain productivity, crude protein content and amino acid profile to obtain future crosses of cultivars with improved nutritional characteristics. Data from two experiments, which were both conducted in randomized block design and three replicates. Thirty-six early-maturing and 22 extremely early-maturing cultivars were evaluated of the experiments. Grain productivity, crude protein, lysine, methionine, cysteine, threonine, tryptophan, valine, isoleucine, leucine, phenylalanine, histidine and arginine were evaluated. Analysis of variance was performed for each variable and means were compared by Scott-Knott test. Mahalanobis generalized distance matrix was calculated, and the cultivars were grouped using the unweighted pair group method with arithmetic mean (UPGMA). A dendrogram was then constructed, and the cophenetic correlation coefficient was calculated. The group means were compared using the t-test for independent samples. Genetic variability was detected in 13 variables for both maturity groups. For the early-maturing and extremely early-maturing cultivars, five and four groupings were obtained, respectively, based on grain productivity, crude protein content and amino acid profile, indicating that the crossbreeding of these cultivars may be used to improve the grain protein content and amino acid profile. Key words: Zea mays L., genetic variability, nutritional variability, clustering analysis, near-infrared reflectance spectroscopy.
Highlights
Studies on the variability of the nutritional composition of corn are important because they contribute to increase nutrient use efficiency and minimize environmental damage
The aim of this study was to investigate the genetic variability among early-maturing and extremely earlymaturing corn cultivars in relation to grain productivity, crude protein content and amino acid profile to obtain future crosses of cultivars with improved nutritional characteristics
A review performed by Prasanna et al (2001) shows that the QPM (Quality Protein Maize) cultivars with high quality protein provide benefits for human nutrition due to a significant increase on lysine and tryptophan levels compared to conventional corn cultivars
Summary
Studies on the variability of the nutritional composition of corn are important because they contribute to increase nutrient use efficiency and minimize environmental damage. Genetic improvement in corn has mainly focused on increasing grain productivity (PROD), which may have diminished the nutritional value of grain. Idikut et al (2009) and Aliu et al (2012) demonstrated that hybrids and corn populations show an inverse relationship between PROD and the crude proteins (CP) content of grain, and from 1930 to 1991, the level of this nutrient decreased 0.3% per decade (Duvick, 2005). In order to improve the amino acid composition, Shewry (2007) demonstrates the possibility of using genetic engineering strategies to increase both the total protein content and composition of essential amino acids or even for exploitation of natural high lysine mutants
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