CIMMYT Southern Africa Regional Office

Mount Pleasant, Zimbabwe

CIMMYT Southern Africa Regional Office

Mount Pleasant, Zimbabwe

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Ndhlela T.,Crop Breeding Institute | Herselman L.,University of the Free State | Semagn K.,CIMMYT | Magorokosho C.,CIMMYT Southern Africa Regional Office | And 2 more authors.
Euphytica | Year: 2015

Genetic characterisation of breeding lines is of great importance as it enables breeders to maximise heterosis in hybrid combinations as well as in the breeding material. In this study 10 Department of Research and Specialist Services and 13 Centre for the Improvement of Maize and Wheat inbred lines were crossed using a North Carolina II mating scheme and were genotyped using 1,129 single nucleotide polymorphic (SNP) markers. The resultant 72 single cross hybrids together with eight different local checks were evaluated across seven locations in Zimbabwe in the 2009/2010 and 2010/2011 seasons. SNP markers yielded a total of 2,258 alleles and a moderate genetic diversity and polymorphic information content of 0.32 and 0.258, respectively. Clustering of lines did not relate to available pedigree information. Significant positive correlations were recorded for specific combining ability with mid parent heterosis (MPH), high parent heterosis (HPH) and per se performance of hybrids. However, correlations of genetic distances with heterosis under drought conditions were too low to be of predictive value. The HPH and MPH also showed significant positive associations along with high coefficients of determination with per se performance of hybrids, especially under drought. © 2015, Springer Science+Business Media Dordrecht.

Ndhlela T.,Crop Breeding Institute | Herselman L.,University of the Free State | Magorokosho C.,CIMMYT Southern Africa Regional Office | Setimela P.,CIMMYT Southern Africa Regional Office | And 2 more authors.
Crop Science | Year: 2014

Maize (Zea mays) is the most important cereal crop in Zimbabwe and is grown by both large-and small-scale farmers who are located in different agro-ecological zones of the country. The development and dissemination of adapted and high-yielding maize cultivars to these agro-ecological zones involves conducting multi-environment trials (METs). This study was conducted with the objectives of i) understanding complex G × E interaction and stability of single cross hybrids generated using CIMMYT elite drought tolerant lines and Department of Research and Specialist Services (DR&SS) elite drought susceptible lines for grain yield across stress and nonstress environments and ii) to identify genotypes to recommend for further use in the breeding program. Initially, yield data of 80 maize single cross hybrids tested across seven environments during the 2009 to 2010 and 2010 to 2011 seasons were analyzed using the additive main effects and multiplicative interaction (AMMI) biplot method. The analysis was further done for 20 best performing genotypes to facilitate less congested graphical presentation. Combined analysis of variance showed highly significant differences for the G × E interaction, indicating the possibility of selection for stable genotypes. The five AMMI interaction principal component analyses (IPCAs; IPCA1, IPCA2, IPCA3, IPCA4, and IPCA5) explained 82.41% of the variation and they were highly significant. The results showed three genotypes with high yield performance and broad adaptability whilst narrow adaptations were also observed. Agricultural Research Trust Farm was the most powerful site in discriminating among genotypes and the most representative environment. © Crop Science Society of America.

Araus J.L.,University of Barcelona | Cairns J.E.,CIMMYT Southern Africa Regional Office
Trends in Plant Science | Year: 2014

Constraints in field phenotyping capability limit our ability to dissect the genetics of quantitative traits, particularly those related to yield and stress tolerance (e.g., yield potential as well as increased drought, heat tolerance, and nutrient efficiency, etc.). The development of effective field-based high-throughput phenotyping platforms (HTPPs) remains a bottleneck for future breeding advances. However, progress in sensors, aeronautics, and high-performance computing are paving the way. Here, we review recent advances in field HTPPs, which should combine at an affordable cost, high capacity for data recording, scoring and processing, and non-invasive remote sensing methods, together with automated environmental data collection. Laboratory analyses of key plant parts may complement direct phenotyping under field conditions. Improvements in user-friendly data management together with a more powerful interpretation of results should increase the use of field HTPPs, therefore increasing the efficiency of crop genetic improvement to meet the needs of future generations. © 2013 Elsevier Ltd.

Nyakudya I.W.,Bindura University of Science Education | Stroosnijder L.,Wageningen University | Nyagumbo I.,CIMMYT Southern Africa Regional Office
Agricultural Water Management | Year: 2014

Realising that rainwater harvesting (RWH) improves crop productivity, smallholder farmers in semi-arid Zimbabwe modified contour ridges traditionally used for rainwater management by digging infiltration pits inside contour ridge channels in order to retain more water in crop fields. However, scientific studies on crop yield benefits of infiltration pits have not been conclusive. Combining field-edge RWH methods such as contour ridges with infiltration pits with in-field practices may enhance crop yield benefits. Thus, the objective of the study was to assess soil moisture and maize yield improvement of combining infiltration and planting pits. Field experiments were conducted in Rushinga, Zimbabwe for three seasons at three sites using a split-plot design: main-plot factor, field-edge rainwater management method (RWMM); and split-plot factor, tillage method. Soil moisture content was measured weekly using gravimetric and Time Domain Reflectometry (TDR) methods. A household and field survey to establish farmers' perceptions, typology and availability of field-edge RWMM was conducted. In order to share experiences and enhance stakeholders' learning, field days were held. Lateral movement of soil water was measured up to 2m downslope from infiltration pits, hence infiltration pits did not improve maize yield and soil moisture content in the cropping area. Maize yield (kgha-1) was 45% higher under conventional tillage (2697) than planting pits (1852) but the yield gap decreased from 90 to 30% in the first and third year respectively. The value of infiltration pits is in reducing soil erosion by water and growing high value horticultural crops inside and close to pits, a view shared by host farmers and other stakeholders. Planting pits are an option for farmers without access to draught power and a fall-back method. Research is required to determine soil moisture, maize yield benefits and waterlogging risk in fields with underlying impermeable layers that enhance lateral flow of water. © 2014 Elsevier B.V.

Mupangwa W.,CIMMYT Southern Africa Regional Office | Mutenje M.,CIMMYT Southern Africa Regional Office | Thierfelder C.,CIMMYT Southern Africa Regional Office | Nyagumbo I.,CIMMYT Southern Africa Regional Office
Renewable Agriculture and Food Systems | Year: 2016

Continuous conventional tillage coupled with unsystematic cereal/legume rotations has promoted low crop productivity on smallholder farms. A multi-locational study was established in three agro-ecoregions (AEs) of Zimbabwe. The aim of the study was to determine the effect of four tillage systems (conventional plowing, planting basins, rip-line and animal traction direct seeding systems) on maize (Zea mays L.), cowpea [Vigna unguiculata (L.) Walp] and soybean [Glycine max (L.) Merrill] yields, and evaluate the economic performance of the conservation agriculture (CA) systems relative to conventional plowing. Each farmer was a replicate of the trial over the three cropping seasons. In the high (750–1000 mm per annum) and low (450–650 mm) rainfall AEs, conventional practice and CA systems gave similar maize grain yield. Under medium rainfall conditions (500–800 mm) planting basins, rip-line and direct seeding systems gave 547, 548 and 1690 kg ha−1 more maize yield than the conventional practice. In the high and low rainfall AEs, conventional practice and planting basins had the lowest maize production risk. Cowpea yield was 35 and 45% higher in the rip-line and direct seeding than conventional practice. Soybean yield was higher in rip-line (36%) and direct seeding (51%) systems than conventional practice. Direct seeding system gave the highest net benefits in all AEs. A combination of long-term biophysical and socio-economic assessments of the different cropping systems tested in our study is critical in order to fully understand their performance under different AEs of Zimbabwe. Copyright © Cambridge University Press 2016

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