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Accueil du site → Doctorat → Inde → 2011 → Genetics of grain iron and zinc concentration in pearl millet (Pennisetum glaucum (L.) R. Br.)

Tamil Nadu Agricultural University (2011)

Genetics of grain iron and zinc concentration in pearl millet (Pennisetum glaucum (L.) R. Br.)

Govindaraj, M

Titre : Genetics of grain iron and zinc concentration in pearl millet (Pennisetum glaucum (L.) R. Br.)

Auteur : Govindaraj, M

Etablissement de soutenance : Tamil Nadu Agricultural University

Grade : PhD thesis 2011

Pearl millet (Pennisetum glaucum (L.) R. Br.) is an important staple crop for millions of poor rural households in the semi-arid tropics of Asia and Africa. Owing to its importance for addressing micronutrient malnutrition problem, especially iron (Fe) and zinc (Zn) concentration, considerable global efforts are under way to improve its Fe and Zn levels through genetic enhancement. Hence, this dissertation was aimed at investigating some of the factors that have direct bearing on breeding efficiency. These includes gene action, combining ability and heterosis for Fe and Zn, intra-population variance, efficiency of single plant selection, association of grain Fe and Zn concentration with grain yield and key agronomic traits (1000-grain mass and flowering), and response to recurrent selection. In two sets of line x tester studies, parents were observed having a wide range of genetic variability for both grain Fe (34 -102 mg kg-1) and Zn (34 - 84 mg kg-1) concentration and this was also reflected in both sets of hybrids. over two season, ICMB 93222, ICMB 98222, 863 B, ICMB 95333, ICMB 96333 among seed parents (lines) and IPC 774, IPC 616, IPC 1650, IPC 1178, IPC 536 and IPC 735 amongst pollen parents (testers) were found to have >60 mg kg-1 Fe and >55 mg kg-1 Zn concentration. All these inbreds are designated seed/pollinator parents in elite genetic backgrounds, indicating good scope for their effective use in hybrid and hybrid parents breeding. The predictability ratio was around unity for all traits, revealing the predominance of GCA (additive) variance controlling these traits in both the sets. Highly significant positive correlation between mid-parent value and per se performance of hybrids further confirmed the predominant role of additive gene action for these traits. using both parameters (per se performance and positive significant gca effect), ICMB 93222, ICMB 98222, 863b, ICMB 91222, IPC 1650, IPC 843, IPC 774, IPC 1178, IPC 689 and IPC 735 were identified as good general combiners for grain Fe and Zn in hybrid breeding. similarly, 863 B x IPC 404 and ICMB 95333 x IPC 404 for both grain Fe and Zn, while ICMB 94111 x IPC 1178 and ICMB 89111 x IPC 843 for grain Zn had positive significant sca effects. Low level of heterosis over mid-parent for grain Fe and Zn, no hybrid with significant heterosis over better-parent, and largely additive genetic variances would imply that there would be little opportunity, to exploit heterosis for these traits. In fact, to breed hybrids with high Fe and Zn levels, these micronutrients will have to be incorporated in both parental lines. Higher degree of positive and highly significant correlation between S0 plants and their respective S1 progenies both for grain Fe and Zn in all four populations indicated that individual plant performance for these micronutrients can be as effectively used for selection as the S1 progeny performance. Highly significant positive correlation between Fe and Zn revealed good prospects of concurrent genetic improvement for both micronutrients. Recurrent selection for high grain Fe and Zn in two populations increased Fe concentration by 2.4% to 8.0% and Zn concentration by 5.4% to 7.9%. It also increased 1000-grain mass by 4.8% and 14.2%, changed flowering time from -2.3% to 0.8% and had no adverse effect on grain yield. This would indicate that selection for Fe and Zn concentration can be made without compromising on grain yield and other agronomic traits such as large seed size and earliness

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Page publiée le 22 septembre 2012, mise à jour le 31 janvier 2021