Maize Ear Digital Imaging for Yield Components Assessment

Posted on Published Journals, Research Publication, April 8, 2019

User friendly digital tool for faster data collection

In Sub-Saharan Africa, many food security programs aim to increase crop yields by developing and disseminating better seeds and agronomy to millions of smallholder farmers. In the case of maize, research and development organizations use key indicators like grain yield, or maize cob number and size to understand the performance of the maize plant under different environmental conditions. But these indicators are still labor-intensive and expensive to measure. CIMMYT has developed a digital imaging tool called Maize Ear Analyzer that collects maize cob and grain parameters 90% faster than traditional methods (Makanza et al, 2018). This imaging tool can be adapted to other crops.

Zelalem Bekeko, Chemeda Fininsa, Dagne Wegary, Temam Hussien, Shimelis Hussien and Belachew Asalf. 2018. Combining ability and nature of gene action in maize (Zea mays L) inbred lines for resistance to gray leaf spot disease (Cercospora zeae maydis) in Ethiopia.

Posted on Eastern Africa Publications, Published Journals, Research Publication, January 23, 2019

Crop Protection 112: 39–48. DOI: 10.1016/j.cropro.2018.05.010

Abstract: Ten elite maize inbred lines were selected based on all over per se performance and resistance to gray leaf spot (GLS) disease. 45 F1 single cross hybrids were evaluated with three replications compared to three commercial checks. All the necessary yield, agronomic and GLS disease data were recorded. In all the studied traits highly significant genotypic differences were observed indicating the existence of genetic variability among the crosses. Among all inbred lines, five were identified as promising sources for GLS disease resistance.  Analysis of epidemiological data and disease progress helped narrowing down to three populations that combine good yield, yield related traits and GLS disease resistance. Thus, these parents were recommended to be used in breeding programs and four potential high yielding and GLS resistant single cross hybrids were identified (CML-395/CML-383, CML-395/Sc-22, CML-395/CML-197 and CML-383/CML-197). Therefore, it is recommended that these hybrids can be used for direct production where this disease is the most prevalent and/or for further breeding programs in generating novel hybrids for future use.

Setimela P, Zaman-Allah MA, Gasura E, Cairns JE, Thierfelder T, Prasanna BM. 2018. When the going gets tough: performance of stress tolerant maize under conservation agriculture during the 2015/16 El Nino season in southern Africa.

Posted on Published Journals, Research News, Research Publication, Southern Africa Publications, January 23, 2019

Agriculture, Ecosystems and Environment 268, 79-89. DOI: https://doi.org/10.1016/j.agee.2018.09.006

Abstract: The 2015/2016El Niño was the most severe on record in southern Africa and was associated with drought and heat stress. To help farmers to cope with such extreme production constraints the International Maize and Wheat Improvement Centre (CIMMYT), has been developing multiple stress tolerant maize varieties through a rapid-cycle breeding strategy. These CIMMYT stress tolerant maize hybrids were evaluated using two types of trials. The first one comprised a regional on-farm trial with forty maize varieties (20 early-intermediate and 20 intermediate-late varieties), planted across 30 locations in four countries in southern Africa. The second set comprised a multi-locational evaluation trial with six hybrids that were tested under conventional ridge tillage (CP) and conservation agriculture (CA) using a randomized block design with each farm as replicate in nine extension planning areas (EPA), across two years. CIMMYT stress tolerant varieties outperformed non stress tolerant varieties. CZH142020 (5.6 t ha −1) and CZH131008 (4.8 t ha −1) had significantly higher yield advantage over commercial control varieties (<4.5 t ha −1) in both early and late maturity groups. They also had larger grains and smaller ear uniformity index (EUI) (calculated as among plots ear size variance); compared non-stress tolerant varieties. In the CA/CP evaluation trial, varieties under CA yielded ≥0.7 t ha-1 more grain compared to those under CP. Therefore, combinations of climate-smart agriculture technologies are required to mitigate negative effects of extreme events like El Niño and increase resilience of low-input farming systems.

Marenya, Paswel P. & Erenstein, Olaf & Prasanna, Boddupalli & Makumbi, Dan & Jumbo, MacDonald & Beyene, Yoseph, 2018. “Maize lethal necrosis disease: Evaluating agronomic and genetic control strategies for Ethiopia and Kenya,”

Posted on Published Journals, Research Publication, January 23, 2019

Marenya, Paswel P. & Erenstein, Olaf & Prasanna, Boddupalli & Makumbi, Dan & Jumbo, MacDonald & Beyene, Yoseph, 2018.Maize lethal necrosis disease: Evaluating agronomic and genetic control strategies for Ethiopia and Kenya,” Agricultural Systems, Elsevier, vol. 162(C), pages 220-228 ; DOI: 10.1016/j.agsy.2018.01.016

Abstract: Maize lethal necrosis disease (MLN) was first diagnosed in eastern Africa in the 2010’s and is a big threat to their maize-based agri-food systems with estimated losses amounting to US$261 million in Ethiopia and US$198 million in Kenya. This paper reviews the agronomic and policy options to contain MLN and comparatively analyzes the feasibility of using maize-bean rotations and MLN-tolerant germplasm as key alternative strategies for managing MLN. The paper finds that although maize-legume rotations are sound agronomic recommendations and are crucial for long term maize production system viability, their widespread application over large geographic areas for MLN control is economically challenging given that maize is a preferred staple. We conclude that scaling MLN-tolerant germplasm proves highly viable with estimated multiplier benefits of US$245-756 million in Ethiopia and US$195-678 million in Kenya, and benefiting up to 2.1 million people in Ethiopia and 1.2 million in Kenya. Given that the threat of MLN is present and ongoing, the food and economic security of maize-based agrarian economies in eastern Africa will critically depend on the successful mainstreaming of MLN tolerance in their maize seed systems.

Manje Gowda & Yoseph Beyene & Dan Makumbi & Kassa Semagn & Michael S. Olsen & Jumbo M. Bright & Biswanath Das & Stephen Mugo & L. M. Suresh & Boddupalli M. Prasanna (2018) Discovery and validation of genomic regions associated with resistance to maize lethal necrosis in four biparental populations.

Posted on Published Journals, Research Publication, January 23, 2019

Mol Breeding (2018) 38:66 https://www.ncbi.nlm.nih.gov/pubmed/29773962 DOI: 10.1007/s11032-018-0829-7

Abstract: Maize lethal necrosis (MLN) disease is a recent maize disease in sub-Saharan Africa that threatens the food security of the region. Understanding the genetic basis of MLN resistance is crucial. In this study, we used four biparental populations applied linkage mapping and joint linkage mapping approaches to identify and validate the MLN resistance-associated genomic regions. All populations were genotyped with low to high density markers and phenotyped in multiple environments against MLN under artificial inoculation. Phenotypic variation for MLN resistance was significant and heritability was moderate to high in all four populations for both early and late stages of disease infection. Linkage mapping revealed three major quantitative trait loci (QTL) on chromosomes 3, 6, and 9 that were consistently detected in at least two of the four populations. Phenotypic variance explained by a single QTL in each population ranged from 3.9% in population 1 to 43.8% in population 2. Joint linkage association mapping across three populations with three biometric models together revealed 16 and 10 main effect QTL for MLN-early and MLN-late, respectively. The QTL identified on chromosomes 3, 5, 6, and 9 were consistent with the QTL identified by linkage mapping. Ridge regression best linear unbiased prediction with five-fold cross-validation revealed high accuracy for prediction across populations for both MLN-early and MLN-late. Overall, the study discovered and validated the presence of major effect QTL on chromosomes 3, 6, and 9 which can be potential candidates for marker-assisted breeding to improve the MLN resistance.

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