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

Abstract

Development of inbred lines with high general combining ability (GCA) is an important aspect of hybrid breeding research. Although broad‐based open‐pollinated populations (varieties and composites) are widely used to assess GCA of inbred lines and population progenies, identification of the most effective testers has remained a continuing challenge. Two broad‐based and diverse populations of pearl millet [Pennisetum glaucum (L.) R. Br.] were crossed with 14 diverse inbred lines in each of two experiments to produce 56 topcross hybrids, which were evaluated along with their parental lines for grain Fe and Zn densities. Results showed that there was highly significant and moderately high positive correlation between the topcross hybrid performance per se (a measure of GCA) produced with the two testers, both for Fe and Zn densities in both experiments. However, the correlation between performance per se of lines and their topcross hybrids averaged over both testers (giving more reliable estimates of GCA than individual testers) was even higher for both micronutrients and in both experiments. Thus, while each tester was effective in identifying 30 to 35% of the top‐ranking high general combiners as reflected in topcross hybrid performance, line performance per se was even more effective in identifying these top‐ranking combiners for both micronutrients in both experiments, indicating that based on performance per se lines can be selected for high GCA of Fe and Zn densities in pearl millet.

Terminal drought and a d dwarfing gene affecting grain iron and zinc density in pearl millet

“…There was highly significant and high positive correlation between these two micronutrients in tall as well as dwarf isolines, both under drought and control. Similar relationships between these two micronutrients have been reported in earlier studies on pearl millet Kanatti et al, 2016;Rai et al, 2013), and in other cereals such as sorghum (Ashok Kumar et al, 2013), maize (Oikeh et al, 2004), rice (Anandan et al, 2011;Stangoulis et al, 2007) and wheat (Velu et al, 2016). Such correlations may result more likely from tight linkage between the loci responsible for these two micronutrients.…”

“…The isolines were planted in a split-plot design with three replications during the 2010 and 2012 summer season under irrigated control as well as under imposed terminal drought in Alfisols at ICRISAT, Patancheru. Earlier studies Kanatti et al, 2016) have shown these soils having far higher Fe and Zn content than critical levels of Fe (2.6e4.5 mg kg À1 ) and Zn (0.6e1.0 mg kg À1 ) required by plants for normal growth and dvelopment (Sahrawat and Wani, 2013). The two treatments planted in strips were separated by an 8-row buffer planting.…”

Inbreeding Effects on Grain Iron and Zinc Concentrations in Pearl Millet

“…Given the mean performance over years and the two treatment levels, the changes in Fe concentration at various homozygosity levels were positively and highly significantly correlated with changes in Zn concentration, not only in EBC (r = 0.89, P < 0.05) and HHVBC (r = 0.97, P < 0.01), but also in SRBC (r = 0.94, P < 0.05). Such correlated changes are not unexpected, as several previous pearl millet studies have shown highly significant and high positive correlations between these micronutrients (Velu et al, 2007(Velu et al, , 2008a(Velu et al, , 2008bGupta et al, 2009;Rai et al, 2012Rai et al, , 2013Govindaraj et al, 2013;Kanatti et al, 2014aKanatti et al, , 2014bKanatti et al, , 2016. Similar results have also been reported in other cereals, such as maize (Arnold et al, 1977;Oikeh et al, 2003Oikeh et al, , 2004, rice (Stangoulis et al, 2007;Anandan et al, 2011), wheat (Garvin et al, 2006;Peleg et al, 2009;Zhang et al, 2010;Velu et al, 2011a), and finger millet [Eleusine coracana (L.) Gaertn.]…”

“…The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), in alliance with the HarvestPlus Challenge Program of the Consultative Group on International Agricultural Research (CGIAR), has recently undertaken a major initiative to breed high-yielding parental lines of pearl millet with high Fe and Zn concentrations. It has been shown that, unlike grain yield, performance per se of lines is highly significantly and positively correlated with general combining ability for Fe and Zn concentrations in pearl millet, implying that the lines selected for high Fe and Zn concentrations will also be high general combiners for these micronutrients (Velu et al, 2011b;Govindaraj et al, 2013;Kanatti et al, 2014aKanatti et al, , 2016. Development of inbred lines with high Fe and Zn concentrations depends on the level of and variability for these micronutrients in the base population (whether F 2 s, OPVs, or composites), and on the magnitude, direction, and pattern of inbreeding effects.…”

Status of Global Pearl Millet Breeding Programs and the Way Forward

“…This fourth phase is marked by the release of the largest number of cultivars and remarkable productivity increase (Kumara et al, 2014). Biofortification of the grain for micronutrients, mainly iron and zinc (Rai et al, 2013; Kanatti et al, 2016a, 2016b), and application of molecular technologies to expedite the cultivar development process were also strengthened. Research aimed at further diversification of the seed and restorer parents, improving disease resistance, and development of extra‐early hybrids for adaptation to specific niches is being conducted (Singh et al, 2014).…”