Evaluation of South African high quality protein maize (Zea mays L.) inbred lines under optimum and low nitrogen conditions and the identification of suitable donor parents

English: Genetic improvement of QPM can assist to better the livelihoods of resource poor communities and farmers in SA who rely on maize. QPM germplasm from the ARC-GCI was evaluated to generate information to assist breeders in improving the breeding programme through designing efficient selection procedures that will reduce the time and cost required to develop lines with improved nutritional quality; in the process benefiting small-scale farmers. Pollen parent effect was determined by selfing and cross-pollinating 12 QPM inbred lines for tryptophan content. The two pollination methods did not differ significantly for tryptophan content. Single ANOVAs detected genotypic differences for grain quality traits, while combined ANOVAs across eight environments detected highly significant genotype, environment and GEI effects for all traits except endosperm hardness. The AMMI and GGE biplot analyses explained more than 60% of GEI variation. GGE biplots were the best for visualisation of environments and cultivar performance. AMMI and GGE biplots were similar in identifying high performing genotypes for all traits except for oil content, and the most stable genotypes except for starch and tryptophan content. The GGE biplots identified the ideal genotypes as KO54W, KO54W, Hans Male, SO503W and CML144 for QI, tryptophan, protein, oil and starch content respectively. GGE biplots identified Cedara optimum N as the most representative and discriminating environment for QI, tryptophan and starch content, Tshiombo optimum N for protein and Potchefstroom optimum N for oil content. Twenty QPM and non-QPM genotypes were evaluated under low and optimum N conditions in two locations and highly significant environment effects were observed for all traits, whilst significant genotypic differences and GEI were observed for tryptophan content and QI. Most of the traits improved with increased N level. QPM varieties performed significantly better than non-QPM varieties for tryptophan con
Afrikaans: Genetiese verbetering van QPM kan bydra tot die verbetering van lewenskwaliteit van hulpbronarm gemeenskappe in SA wat afhanklik is van mielies. QPM kiemplasma van die LNR-SGI is geëvalueer om inligting te genereer wat telers kan help met die verbetering van teelprogramme deur effektiewe seleksieprosedures te ontwerp wat die tyd en koste vir die ontwikkeling van lyne met verbeterde voedingswaardes sal verminder, wat gelyktydig ook bestaansboere sal bevoordeel. Stuifmeelouer effekte is bepaal deur die self- en kruisbestuiwing van 12 QPM ingeteelde lyne vir triptofaan inhoud. Die twee bestuiwingsmetodes het geen betekenisvolle verskille vir triptofaan inhoud getoon nie. Enkel ANOVAs het genotipiese verskille getoon vir graankwaliteitseienskappe, terwyl gekombineerde ANOVAs oor agt omgewings hoogs betekenisvolle verskille getoon het vir genotipe, omgewing en GEI effekte vir alle eienskappe behalwe endosperm hardheid. Die AMMI en GGE “biplot” analises het meer as 60% van die GEI variasie verklaar. GGE “biplots” was die beste vir die visualisering van omgewings and cultivar prestasie. AMMI en GGE “biplots” was soortgelyk vir die identifikasie van hoogs produktiewe genotipes vir alle eienskappe behalwe stysel en triptofaan inhoud. GGE “biplots” het die mees ideale genotipes geïdentifiseer as KO54W, KO54W, Hans Male, SO503W en CML144 vir QI, triptofaan, proteïen, olie en stysel inhoud onderskeidelik. GGE “biplots” het Cedara optimum N as die mees verteenwoordigende en diskriminerende omgewing geïdentifiseer vir QI, triptofaan en stysel inhoud, Tshiombo optimum N vir proteïen, en Potchefstroom optimum N vir olie inhoud. Twintig QPM en nie-QPM genotipes is geëvalueer onder lae en optimum N omstandighede in twee omgewings, en hoogs betekenisvolle omgewingseffekte is gesien vir alle eienskappe, terwyl betekenisvolle genotipiese verskille en GEI gesien is vir triptofaan inhoud en QI. Meeste van die eienskappe het verbeter onder hoër N toestande. QPM genotipes het bet
National Research Foundation
ARC-GCI