Enhancing climate resilience using stress-tolerant maize in conservation agriculture in southern Africa.

Recurrent and widespread droughts in southern Africa (SA) reduce agricultural productivity and increase food insecurity among smallholder farmers. The average growing-season temperatures are expected to increase by 2.5°C. In SA maize is a staple food, accounting for more than 30% of total calories. The crop is mostly grown by smallholder farmers with limited inputs of fertilizers and improved seed. Most of the maize cultivars grown by farmers are susceptible to heat and drought. Multi-stress-tolerant maize germplasm is one of the climate smart agriculture (CSA) components and, when used in combination with others, can sustainably increase production and resilience of agricultural systems. In this paper we review the performance and economic benefits of drought-tolerant maize cultivars under conventional monocropping practice, under conventional intercropping and in Conservation Agriculture (CA) as part of sustainable intensification to ensure food security for smallholder farmers.

Morphological and Genetic Characterization of Local Maize Accessions from Emilia Romagna Region, Italy

Italian maize germplasm is particularly rich in local materials and each region is characterized by the presence of peculiar local varieties deriving from centuries of adaptation, selection and cultivation. While the introduction of hybrids, during the 1950s, led to the disappearing of many of these varieties, some have been maintained in cultivation by farmers, frequently in marginal areas, as a kind of family heritage. Local varieties were identified throughout field surveys carried out in recent years. The discovery of a traditional popcorn variety over the most common flint and semi-flint materials used for production of polenta was interesting. Since these varieties have never been adequately described and reported in scientific literature, this study was aimed to solve this lack of knowledge on recently discovered local maize populations. Characterization represents the first step of a process focused on the preservation and possible exploitation of important genetic resources. Traditional materials are a useful reservoir of genes for adaptation to local conditions and climate changes. Adequate breeding programs can use such germplasm for developing new and more resilient varieties. These local materials have been characterized at the morphological level highlighting plant, ear and kernel differences. Genetic characterization, carried out on 455 individuals by the use of 10 SSR markers, revealed 62 different alleles ranging from four for markers phi127, phi076 and phi084 to nine for marker p-bnlg176. The landraces are well distinguishable at genetic level since 40% of genetic variability is present among accessions. Five landraces are characterized by the presence of private alleles and heterozygosity levels are generally good. These findings support the possibility to correctly preserve local materials through in situ conservation. Phylogenetic analysis evidenced the presence of varietal clusters, the clearest one formed by three red-pigmented accessions. STRUCTURE analysis revealed that five landraces have a well-defined genetic attribution while the remaining two (EMR04-Mais Rosso di Rasora and EMR10-Mais del Principe di Scavolino) are both constituted by two different backgrounds.

Assessment of repeatability and representativeness of testing sites for provitamin a maize in savanna agro-ecologies of Nigeria

Identification of ideal testing sites for selection of superior maize (Zea mays L.) germplam is vital to the success of a maize breeding programme. Sixteen provitamin A maize genotypes were evaluated at seven locations in savanna agro-ecologies of Nigeria for 3 yr to assess the representativeness, discriminating ability, and repeatability of the testing sites and to identify ideal testing sites for selection of superior maize germplasm. Location, year, and their interaction effects were significant for grain yield and mostmeasured traits while genotype and genotype ´x year interactive effects were significant for grain yield. The genotype main effects plus genotype ´x environment interaction (GGE) biplot analysis revealed PVA SYN-18 F2 as the highest-yielding and most stable genotype across environments. The GGE biplot identified Zaria, Saminaka, and Kaboji as the most discriminating locations. Also, the biplot identified Kaboji, Batsari, Saminaka, and Zaria as the most repeatable locations. Zaria and Saminaka, being among the most discriminating, representative and repeatable locations, were considered as the core testing sites for selection of superior maize genotypes for release and commercialization. The core testing sites identified in this study should facilitate the identification of stable and high-yielding maize germplasm adaptable to the savannas agro-ecologies of Nigeria.

Heterosis and Heterotic Grouping among Tropical Maize Germplasm

Maize (Zea mays L.) is the most important staple cereal cultivated in sub-Saharan Africa but its productivity is considerable low due to several factors. Development and deployment of maize hybrids have been reported as one of the crucial options in achieving sustainable maize production in sub-Saharan Africa. Information on the heterotic response among available genetic materials in a breeding program is valuable before commencement of any hybrid development program. Unlike the temperate germplasm, maize tropical germplasm is characterized with wide genetic base and genetic complexities and thus, proper organization of the pools, populations, varieties and inbreds that can serve as parental materials for hybrid development through identification of a distinct heterotic groups and patterns among tropical germplasm becomes very essential. This paper reviewed past research efforts at characterizing heterotic response among tropical maize genetic materials with a view to point out merits and demerits in the methods used and future direction towards achieving sustainable hybrid cultivation and enhancing food security in the sub-region.

Genotype by Environment Interaction by AMMI and GGE Bi-Plot Analysis for Maize (Zea Mays L.) for Transitional High Land Agroecology of Ethiopia.

The current research examined the magnitude of genotype by environment interaction (G x E) and evaluated the adaptability and stability of maize genotypes for grain yield in Ethiopia's transitional highland agroecology using an additive main effects and multiplicative interaction (AMMI) model. The study's goals were to first assess the yield output and stability of maize genotypes in Ethiopia's transitional highlands, and then to investigate the effect of genotype- environment interaction on genotype yield. During the main season of 2017/2018, thirteen advanced maize genotypes which was selected from different observation trials with two commercial check hybrids were evaluated at five representative locations for agroecology. The experiment was set up using an alpha lattice (3*5) with three replications and two rows per plot. AMMI showed highly significant(P < 0.001) variation of grain yield was observed due to the effect of genotype (G), Environment(E) and their interaction (G x E). In fact, all genotypes evaluated in representative locations for this agroecology had higher grain yield advantages than the best commercial check except one genotype. Overall, this study discovered the possibility of fast releasing and overtake of new maize hybrids for transitional high land agroecology of Ethiopia to exploits availability maize germplasm to maximize production. The best candidate genotype, MABK181261 is a stable and high-yielding product. It is recommended for release as a commercial hybrid alternative after national variety verification trial in a high land transitional agroecology of Ethiopia. In addition, the parental lines of this genotypes can be used to enhance germplasm of opposite heterotic group in maize breeding for East Africa.

Adaptation assessment of drought tolerance in maize populations from the Sahara in both shores of the Mediterranean Sea

Drought is the main stress for agriculture, and maize (Zea mays L.) germplasm from the Sahara has been identified as potential source of drought tolerance; however, information about adaptation of semitropical maize germplasm from the Sahara to temperate areas has not been reported. Our objective was assessing the adaptation of maize germplasm from Saharan oases as sources of drought tolerance for improving yield and biomass production under drought conditions in temperate environments. A collection of maize populations from Saharan oases was evaluated under drought and control conditions in Spain and Algeria. Algerian populations were significantly different under drought for most traits, and the significant genotype × environment interactions indicated that drought tolerance is genotype-dependent, but tolerance differences among genotypes change across environments. Based on yield, the Algerian maize populations PI527474, PI527478, PI527472, PI527467, PI527470, and PI527473 would be appropriate sources of drought tolerance for temperate environments. Concerning biomass production, the most interesting populations were PI527467, PI542685, PI527478, and PI527472. These Saharan populations could provide favorable alleles for drought tolerance for temperate breeding programs, and could also be used for studying mechanisms and genetic regulation of drought tolerance.