Genetic diversity, population structure and inter-trait relationships of combined heat and drought tolerant early-maturing maize inbred lines from west and central Africa

Open Access Journal; Published online: 04 Sept 2020Adequate knowledge and understanding of the genetic diversity and inter-trait relationships among elite maize inbred lines are crucial for determining breeding strategies and predicting hybrid performance. The objectives of this study were to investigate the genetic diversity of 162 early maturing white and yellow tropical maize inbred lines, and to determine the population structure, heterotic groups and inter-trait relationships among the lines. Using 9684 DArT single nucleotide polymorphism (SNP) markers, a gene diversity (GD) of 0.30 was recorded for the inbred lines with polymorphic information content (PIC) ranging from 0.08 to 0.38. The genetic relatedness among the inbred lines evaluated revealed six different groups based on the history of selection, colour of endosperm and pedigree. The genotype-by-trait (GT) biplot analysis identified inbred 1 (TZEI 935) as outstanding in terms of combined heat and drought (HD) tolerance with the base index analysis identifying 15 superior inbreds in the HD environment. A wide range of genetic variability was observed among the inbred lines, indicating that they are an invaluable resource for breeding for HD tolerance in maize breeding programmes, especially in West and Central Africa

Use of GGE biplot for targeting early maturing maize cultivars to mega-environments in West Africa

Maize (Zea mays L.) is an important staple food consumed by people with varying food preferences and socio-economic backgrounds in West Africa (WA). Genotype by environment interactions (G 7E) exist in WA implying the need for extensive testing of cultivars in multiple environments over years before cultivar realistic recommendations can be made. This study examined the effect of G 7E on the performance and stability of early cultivars and to identify core test locations in the mega-environments of WA. Across locations, 2004 TZE-W Pop STR C4 produced the highest grain yield and was the most stable cultivar. DMR-ESRW QPM produced the lowest yield. The test environments contributed about 83.4% of the total variation in grain yield, while genotypes accounted for 1.5% and G 7 E, 11%. Test environments were classified into four mega-environments, namely, Katibougou, Sotouboua, Ejura, and Bagou as the first group; the second group consisted of Manga, Nyankpala, Bagauda, Yendi, Angaredebou, Mokwa, Katibougou, and Zaria; while the third group comprise of Ativeme, and Ikenne; and the fourth, Ina. Test locations Ejura, Sotouboua and Bagou and Katibougou were highly correlated in their ranking of the genotypes in group 1, suggesting that a promising early maturing cultivar selected in one of these locations in one country will also be suitable for production in the other locations within the same mega-environments in different countries. Kita was identified as the ideal location, while Zaria was close to the ideal location.Le ma\uefs (Zea mays L.) est une nourriture principale consomm\ue9 par des personnes \ue0 pr\ue9f\ue9rence alimentaires et un pass\ue9 socio-\ue9conomique vari\ue9s en Afrique de l'Ouest. Une interaction G\ue9notype et Environnement (G 7E) \ue9tait trouv\ue9e, impliquant ainsi le besoin en test extensive des cultivars sur plusieurs ann\ue9es avant toute recommandation. Le but de cette \ue9tude \ue9tait d'examiner l'effet G 7E sur la performance et la stabilit\ue9 des cultivars pr\ue9coces, ainsi que d'identifier le test principal de milieu dans les m\ue9ga-environnements de l'Afrique de l'Ouest. A travers les milieux, 2004 TZE-W Pop STR C4 avait produit le rendement en grain le plus \ue9lev\ue9 et \ue9tait le cultivar le plus stable. DMR-ESRW QPM avait induit le rendement le moins \ue9lev\ue9. La contribution du test d'environnements \ue9tait d'environ 83.4% de la variation totale du rendement en grain, pendant que les g\ue9notypes et G 7 E pr\ue9sentaient 1.5% et 11%, respectivement. Les tests d'environnements \ue9taient classifi\ue9s en quatre m\ue9ga-environnements \ue0 savoir, Katibougou, Sotouboua, Ejura, and Bagou comme premier groupe; Manga, Nyankpala, Bagauda, Yendi, Angaredebou, Mokwa, Katibougou, and Zaria comme deuxi\ue8me groupe, alors que le troisi\ue8me groupe comprenait Ativeme, et Ikenne et le quatri\ue8me, Ina. Le test de milieux Ejura, Sotouboua, Bagou et Katibougou \ue9taitent hautement corr\ue9l\ue9 sur le plan ranking des g\ue9notypes au sein du groupe 1, sugg\ue9rant qu'un cultivar pr\ue9coce promettant s\ue9lectionn\ue9 dans un de ces milieux dans un pays sera appropri\ue9 pour la production dans d'autres milieux au sein des m\ueames m\ue9ga-envoronnements dans diff\ue9rents pays. Kita \ue9tait identifi\ue9 comme un milieu ideal, alors que Zaria \ue9tait proche du milieu ideal

Enhancing productivity of farmer-saved seed yam in Ghana: Positive selection and neem leaf powder factors

Recycling of diseased and pests infested seed yam ( Dioscorea spp.) has resulted in drastic yield reductions in yam production. The objective of this study was to determine the effect of positive selection on the quality of farmer-saved seed yam and also evaluate the effect of neem leaf powder in managing plant parasitic nematodes damage to yam. Two farming systems namely; Positive selection (PS) and Farmer practice (FP) and two soil amendment regimes; neem leaf powder at 20 g stand-1 (NA20) and no neem amendment (NA0) were tested on one variety of yam (Dente). A 2 x 2 x 1 factorial study, mounted on a randomised complete block design in a split plot arrangement was conducted in four replications. Positive selection occupied main plots; while Farmer practice occupied sub-plots. The study was conducted in eight communities located in two municipalities of Ghana, during 2015-2017. Parameters evaluated included Yam Mosaic Virus incidence and severity, incidence and severity of nematode cracks and galling on yam tubers, plant establishment and yield of yam. It was observed that Yam Mosaic Virus (YMV) disease incidence decreased from 38% in 2016 to 31% in 2017 in PS plots as a result of using virus-free planting materials. However, in FP plots, it increased from 67% in 2016 to 72% in 2017. Neem leaf powder amendment resulted in significantly (P< 0.05) low tuber galling (7%) compared with 40% in unamended plots. Similarly, PS plots yielded 7.7 t ha-1 compared to 5.9 t ha-1 in FP fields. In conclusion, Positive selection out-yielded FP by 30.5%; while PS-neem leaf powder interaction resulted in 38.5% over and above FP without neem amendment.Le recyclage des semences d\u2019igname ( Dioscorea spp.) contamin\ue9es par des maladies et des parasites a entra\ueen\ue9 une r\ue9duction drastique du rendement de la production d\u2019igname. L\u2019objectif de cette \ue9tude \ue9tait de d\ue9terminer l\u2019effet de la s\ue9lection positive sur la qualit\ue9 des semences d\u2019igname conserv\ue9es par les agriculteurs et \ue9galement d\u2019\ue9valuer l\u2019effet de la poudre de feuilles de neem dans la gestion des dommages caus\ue9s par les n\ue9matodes parasites des plantes. Deux syst\ue8mes agricoles \ue0 savoir; S\ue9lection positive (PS) et pratique paysanne (PF) et deux r\ue9gimes d\u2019amendement du sol; De la poudre de feuille de neem \ue0 20 g du stand-1 (NA20) et aucun amendement de neem (NA0) ont \ue9t\ue9 test\ue9s sur une vari\ue9t\ue9 d\u2019igname (Dente). Une \ue9tude factorielle de 2 x 2 x 1, mont\ue9e sur une dispositif en\ua0blocs al\ue9atoires complets dans un arrangement en parcelles divis\ue9es, a \ue9t\ue9 men\ue9e en quatre r\ue9p\ue9titions. S\ue9lection positive occup\ue9e parcelles principales; tandis que la pratique paysanne occupait des sous-parcelles. L\u2019\ue9tude a \ue9t\ue9 men\ue9e dans huit communaut\ue9s situ\ue9es dans deux municipalit\ue9s du Ghana en 2015-2017. Les param\ue8tres \ue9valu\ue9s comprenaient l\u2019incidence et la gravit\ue9 du virus de la mosa\uefque de l\u2019igname, l\u2019incidence et la gravit\ue9 des fissures de n\ue9matode et le grippage des tubercules de l\u2019igname, l\u2019\ue9tablissement de la plante et le rendement de l\u2019igname. Il a \ue9t\ue9 observ\ue9 que l\u2019incidence de la maladie caus\ue9e par le virus de la mosa\uefque \ue0 l\u2019igname (YMV) avait diminu\ue9 de 38% en 2016 \ue0 31% en 2017 dans les parcelles PS gr\ue2ce \ue0 l\u2019utilisation de mat\ue9riel de plantation d\ue9pourvu de virus. Cependant, dans les parcelles de PF, il est pass\ue9 de 67% en 2016 \ue0 72% en 2017. L\u2019amendement de poudre de feuille de Neem a entra\ueen\ue9 une r\ue9duction significative du galles des tubercules (P <0,05) (7%) par rapport \ue0 40% dans les parcelles non modifi\ue9es. De m\ueame, les parcelles de PS ont produit 7,7 t ha-1, contre 5,9 t ha-1 dans les champs de PF. En conclusion, la s\ue9lection positive a eu un rendement sup\ue9rieur de 30,5% \ue0 celui de la PF; tandis que l\u2019interaction de la poudre de feuille PS-neem a eu pour r\ue9sultat 38,5% de plus que FP sans amendement de nee

Improved arachis hypogeae variety effect on grain yield fodder quality and livestock growth

The hypothesis that improved groundnut (Arachis hypogea) varieties could improve seed and fodder yield and livestock growth performance was evaluated in two experiments: 1) an agronomic trial to determine the yield and yield component of groundnut varieties; and 2) fodder quality of groundnut varieties and its effect on growth performance of sheep. Four improved groundnut varieties (early-maturing: Yenyawoso, late-maturing: Azivivi, Obolo and Mani pinta) were evaluated for 2 yr in a randomized complete block design with four replications in the agronomic and livestock feeding trials. The results from the agronomic trial showed that the late-maturing varieties had significantly higher pods/plant, pod size, seed and fodder yields than Yenyawoso. Obolo had significantly higher seed yield whilst Azivivi had significantly higher fodder yield among the late-maturing varieties. The fodder quality and feeding trial showed that Yenyawoso had significantly higher dry matter, crude protein and resulted in significantly higher live weight gain of Djallonké rams than the other varieties. The Mani pinta variety had significantly higher live weight gain among the late-maturing varieties. Smallholder crop-livestock farmers interested in both seed and livestock growth could use Mani pinta, those interested in only seed yield could use Obolo and those interested in quality fodder for fattening of small ruminants could use Yenyawoso. Thus, groundnut breeding programs could consider fodder quality in addition to seed and fodder yield as selection criteria to develop varieties that best fit into crop-livestock farming systems

Genome-wide association study reveals genetic architecture and candidate genes for yield and related traits under terminal drought, combined heat and drought in tropical maize germplasm

Open Access Journal; Published online: 15 Feb 2022Maize (Zea mays L.) production is constrained by drought and heat stresses. The combination of these two stresses is likely to be more detrimental. To breed for maize cultivars tolerant of these stresses, 162 tropical maize inbred lines were evaluated under combined heat and drought (CHD) and terminal drought (TD) conditions. The mixed linear model was employed for the genome-wide association study using 7834 SNP markers and several phenotypic data including, days to 50% anthesis (AD) and silking (SD), husk cover (HUSKC), and grain yield (GY). In total, 66, 27, and 24 SNPs were associated with the traits evaluated under CHD, TD, and their combined effects, respectively. Of these, four single nucleotide polymorphism (SNP) markers (SNP_161703060 on Chr01, SNP_196800695 on Chr02, SNP_195454836 on Chr05, and SNP_51772182 on Chr07) had pleiotropic effects on both AD and SD under CHD conditions. Four SNPs (SNP_138825271 (Chr03), SNP_244895453 (Chr04), SNP_168561609 (Chr05), and SNP_62970998 (Chr06)) were associated with AD, SD, and HUSKC under TD. Twelve candidate genes containing phytohormone cis-acting regulating elements were implicated in the regulation of plant responses to multiple stress conditions including heat and drought. The SNPs and candidate genes identified in the study will provide invaluable information for breeding climate smart maize varieties under tropical conditions following validation of the SNP markers

Use of GGE biplot for targeting early maturing maize cultivars to mega environments in West Africa

Maize (Zea mays L.) is an important staple food consumed by people with varying food preferences and socioeconomic backgrounds in West Africa (WA). Genotype by environment interactions (G×E) exist in WA implying the need for extensive testing of cultivars in multiple environments over years before cultivar realistic recommendations can be made. This study examined the effect of G×E on the performance and stability of early cultivars and to identify core test locations in the mega-environments of WA. Across locations, 2004 TZE-W Pop STR C4 produced the highest grain yield and was the most stable cultivar. DMR-ESRW QPM produced the lowest yield. The test environments contributed about 83.4% of the total variation in grain yield, while genotypes accounted for 1.5% and G × E, 11%. Test environments were classified into four mega-environments, namely, Katibougou, Sotouboua, Ejura, and Bagou as the first group; the second group consisted of Manga, Nyankpala, Bagauda, Yendi, Angaredebou, Mokwa, Katibougou, and Zaria; while the third group comprise of Ativeme, and Ikenne; and the fourth, Ina. Test locations Ejura, Sotouboua and Bagou and Katibougou were highly correlated in their ranking of the genotypes in group 1, suggesting that a promising early maturing cultivar selected in one of these locations in one country will also be suitable for production in the other locations within the same mega-environments in different countries. Kita was identified as the ideal location, while Zaria was close to the ideal location

Performance of extraearly maize cultivars based on GGE biplot and AMMI analysis

Published online: 05 October 2011Multi-environment trials (METs) in West Africa have demonstrated the existence of genotype×environment interactions (G×E), which complicate the selection of superior cultivars and the best testing sites for identifying superior and stable genotypes. Two powerful statistical tools available for MET analysis are the additive main effects and multiplicative interaction (AMMI) and the genotype main effect+G×E (known as GGE) biplot. The objective of the present study was to compare their effectiveness in identifying maize mega-environments and stable and superior maize cultivars with good adaptation to West Africa. Twelve extra-early maturing maize cultivars were evaluated at 17 locations in four countries in West Africa from 2006 to 2009. The effects of genotype (G), environments (E) and G×E were significant (P<0 01) for grain yield. Differences between E accounted for 0 75 of the total variation in the sum of squares for grain yield, whereas the G effects accounted for 0 03 and G×E for 0 22. The GGE biplot explained 0 74 of total variations in the sum of squares for grain yield and revealed three mega-environments and seven cultivar groups. The AMMI graph explained 0 13 and revealed four groups each of environments and cultivars. The two procedures provided similar results in terms of stability and performance of the cultivars. Both methods identified the cultivars 2004 TZEE-W Pop STR C4 and TZEE-W Pop STR C4 as superior across environments. Cultivar 2004 TZEE-W Pop STR C4 was the most stable. The GGE biplot was more versatile and flexible, and provided a better understanding of G×E than the AMMI graph. It identified Zaria, Ilorin, Ikenne, Ejura, Kita, Babile, Ina and Angaredebou as the core testing sites of the three mega-environments for testing the Regional Uniform Variety Trials-extra-early