Agronomic, grain and food quality evaluation of 14 sorghum food type genotypes for combining ability, heterosis, environmental and genetic effects in a line x tester analysis

Abstract

In some Central American countries, sorghum totally or partially replaces maize in the tortilla making process. Maize is preferred over sorghum despite sorghum yield advantage. The major constraint to increasing sorghum tortilla consumption is the off color development during alkali cooking. Availability of high yielding sorghum cultivars with superior raw tortilla quality provides an alternative toward a stable food supply in the Central American maize-based food system. Plant breeding efforts to select sorghum cultivars with good raw tortilla quality have been limited by a poor understanding of kernel characteristics affecting tortilla appearance, their inheritance, as well as an appropriate methodology to determine these factors. To address these concerns, 14 parental genotypes were evaluated for agronomic and grain quality traits in five diverse Texas environments. Grain samples from the least weathered environment were evaluated for raw tortilla quality traits. Data were analyzed using analyses of variance, correlations, path analysis and Line x Tester Analysis based on Comstock and Robinson desing II. A tortilla making procedure was modified to optimize tortilla appearance. Maize tortillas were included as checks. Significant environmental and GxE interactions occurred for almost any trait, and they were larger for grain quality traits. Most of the agronomic data showed a strong genetic dependance. High grain yield was the direct phenotypic effect of large number of kernels per panicle, per area and superior threshing ability. Genetically, high grain yield was the direct effect of taller genotypes. Genetic associations of percent grain floaters with decortication loss at 4 min; and percent phenols with amount of extracted anthocyanidins, were high. Additive genetic variances from R-line genotypes were the most important in the expression of many traits. Narrow sense heritability was high for plant high, percent floaters, phenol percent; and moderate for grain yield. BTx623 was the highest yielding parent. Tortillas made from BTx623, B155 and 82CS8407 had the best appearance. The parents A155 and 82CS807 were the best combiners for tortilla appearance. A155*82CS8407 excelled in overall appearance and were favorably compared with white maize tortillas. Results from these set of experiments demostrate that sorghum breeders can genetically improve raw tortilla quality and grain yield.