Assessment of Genotype by Environment interactions and Grain Yield Performance of Extra-Early Maize (Zea Mays L.) Hybrids

Maize (Zea mays L.) is one of the most important cereal crops of Ghana in terms of production and consumption. Currently, it is produced in all the agro-ecological zones of the country. In Ghana, Genotype by Environment interactions (GxE) effects on maize grain yield is usually significant due to the diverse environmental conditions at growing sites. A proper understanding of the effects of GxE on variety evaluation and cultivar recommendations is vital. The study was conducted in 2011 at three locations in Ghana to (i) determine the presence of GxE of 100 extra-early maize genotypes and (ii) To use the GGE biplot methodology to determine grain yield performance and stability of the genotypes evaluated across three environments. The effects of genotype and environment were significant (P < 0.01) for grain yield. However, GxE was not significant for the same trait. TZEEI 8 x TZEEI 51, TZEEI 5 x TZEEI 53, TZEEI 21 x TZEEI 39, TZEEI 27 x TZEEI 36 and TZEEI 4 x TZEEI 6 were identified as high yielding and most stable hybrids. Therefore, these hybrids have the potential for production across the test locations as well as others within the same agro-ecological zones. On the contrary, DODZI, TZEEI 23 x TZEEI 6, TZEEI 19 x TZEEI 24, TZEEI 11 x TZEEI 24 and TZEEI 20 x TZEEI 39 were not only low yielding but also among the least stable genotypes. Keywords: Zea mays, single-cross, stability, multiple environments, Gx

Mapping QTLs for tolerance to salt stress at the early seedling stage in rice (Oryza sativa L.) using a newly identified donor ‘Madina Koyo’

Open Access Article; Published online: 13 Sep 2020Salt stress is a menace to rice production and a threat to food security worldwide. We evaluated 308 F4 families from Sahel 317/Madina Koyo for tolerance to salt stress at the early seedling stage. To better understand genomic regions controlling tolerance in the population, we genotyped the progenies and the two parents using single nucleotide polymorphism (SNP) markers and regressed the genotypic data on their phenotype to detect QTLs. An average reduction of 63.4% was observed for all fitness-related traits among the F4 families. A total of 46 progenies recorded an average salt injury score (SIS) between 1–3 and were rated as tolerant to salt stress at the early seedling stage. A high-density genetic map was constructed for the 12 rice chromosomes using 3698 SNP markers. Multiple interval mapping identified 13 QTLs for SIS, shoot length, shoot dry weight and root length on chromosomes 2, 3, 4, 6, 7, 10 and 12, with trait increasing alleles coming from both parents. Two (qSDW2 and qRL2.2) and three (qSL2, qRL2.1 and qSIS2) QTLs at different regions on chromosome 2 and another two on chromosome 7 (qSDW7 and qSL7) were tightly linked. These QTLs could facilitate breeding for salt tolerance at the early seedling stage as direct selection for one, would mean indirectly selecting for the other. Fine mapping of these novel QTLs in a different genetic background is necessary to confirm their stability and usefulness in breeding for tolerance to salinity in rice