Combining Ability and Heterosis for Grain Iron and Zinc Densities in Pearl Millet

Abstract

Pearl millet [Pennisetum glaucum (L.) R. Br.] is an important staple food crop in the semiarid tropical regions of Asia and Africa. As part of a major initiative to improve its grain Fe and Zn densities, two sets of line × tester studies were conducted. Results showed that the underlying physiological processes determining the grain Fe and Zn densities were largely under additive genetic control, and Fe and Zn densities of the inbred lines per se and their general combining ability (GCA) were positively and highly significantly correlated. This would imply that recurrent selection can be effectively used to improve the breeding populations for grain Fe and Zn densities and that breeding lines selected for high Fe and Zn densities per se are more likely to include those with high GCA for these micronutrients. Lack of better‐parent heterosis indicated that to breed hybrids with high Fe and Zn densities would require high levels of these micronutrients in both parental lines. Highly significant and positive correlations between the Fe and Zn densities, between the GCA of Fe and Zn densities, and between the specific combining ability (SCA) of the Fe and Zn densities showed that simultaneous selection for both micronutrients is likely to be effective with respect to all these performance parameters. Consistency in the patterns of results across both sets of trials and across the environments for all the parameters implies that these results could be of wider application to the genetic improvement of Fe and Zn densities in pearl millet.

Characterization of Sudanese pearl millet germplasm for agro-morphological traits and grain nutritional values

“…When compared with other field crops, the pearl millet materials assessed had comparably higher grain mineral nutrient contents, especially Fe and Zn concentrations, than all other crops (Table S3, available online). This is in agreement with previous studies of these grain mineral micronutrient traits in pearl millet (Velu et al, 2007;Govindaraj et al, 2013), including those based on more representative grain samples than those used in the present study. This finding suggests that these Sudanese pearl millet accessions provide very interesting sources for traits for pearl millet biofortification breeding programmes, provided that the elevated levels detected in this study are validated with more robust sampling methods using sibbed panicles and larger grain samples.…”

Micronutrient Density and Stability in West African Pearl Millet—Potential for Biofortification

“…Studies on grain Zn and Fe densities in pearl millet material grown in India reported ranges of 30 to 80 mg kg −1 Fe and 20 to 70 mg kg −1 Zn on the basis of the means of two environments (Velu et al, 2007;Govindaraj et al, 2013), which are considerably wider than the ranges we observed. Our study shows that for all tested minerals a moderate to high range in grain density exists among the WCA pearl millet genotypes assessed.…”

“…Comparing heritabilities of grain Fe and Zn densities of whole and decorticated grains, which are most important for biofortification, it appears that heritability values for Fe were considerably higher than those for Zn, which has been found in maize as well (Baxter et al, 2012). Previous studies on pearl millet have shown a significant G × E interaction effect for whole-grain densities of Fe and Zn as well (Gupta et al, 2009;Velu et al, 2011;Govindaraj et al, 2013), indicating the general importance of basing biofortification breeding programs on multiple environment testing. The G × E interaction effects for Zn are even higher for whole-grain than for decorticated-grain density, resulting in higher heritabilities for decorticated grain samples.…”

Tester Effect on Combining Ability and Its Relationship with Line Performance per se for Grain Iron and Zinc Densities in Pearl Millet

“…In fact, these correlation coefficients were higher than those observed in the present topcross tester study, indicating that Fe and Zn densities levels of testers would not have any effect on the topcross hybrid performance for these micronutrients. Such results are expected when the characters are largely under additive genetic control, as reported for Fe and Zn densities in pearl millet (Velu et al, 2011; Govindaraj et al, 2013; Kanatti et al, 2014).…”

“…In India, for instance, pearl millet accounts for 20 to 63% of the total cereal consumption in parts of major pearl millet growing states, such as Maharashtra, Gujarat, and Rajasthan (Parthasarathy Rao et al, 2006). Recent studies at the International Crops Research Institute for the Semi‐Arid Tropics (ICRISAT) conducted in alliance with the HarvestPlus Program have shown the presence of large heritable genetic variability for grain Fe and Zn densities in pearl millet (Velu et al, 2008a, 2008b; Rai et al, 2012, 2015b; Govindaraj et al, 2013), indicating good prospects for genetic enhancement of these micronutrients.…”