Agronomic Performance and Compatibility of Common Bean Genotypes Intercropped with Maize

Common bean (Phaseolus vulgaris L.) is one of the most important nutritious food and cash crops grown in Ethiopia. This study evaluated the  compatibility of common bean genotypes to intercropping with maize and assessed land use efficiency of mixed cropping for sustainable intensification  of maize-legume based farming systems. Twenty-five common bean genotypes were evaluated under sole and intercropping with a maize hybrid, BH540,  in 2011 and 2012 at Bako. Significant variations were observed among the common bean genotypes for most studied traits under sole and  intercropping conditions. On average, about 88% yield reduction was recorded for the common bean genotypes intercropped with maize as compared to sole cropping. Genotypes  MEXICO235 X PAN-182 and UBR(92)25-13-1 had higher seed yield under both cropping systems and also showed relatively  lower yield reduction due to intercropping, indicating the compatibility of these genotypes for mixed cropping. Seed yield had positive and significant  correlation only with seeds per pod and harvest index under sole cropping, but it had strong positive association with days to maturity, plant height, pods  per plant, harvest index and number of primary braches under intercropping. Maize-common bean ntercropping slightly increased land use  efficiency and land productivity. Genotypes ICTAJU-95-28, UBR (92)25-13-1 and MEXICO235XPAN-182 exhibited relatively higher total land equivalent ratio  (LER) and relative crowding coefficient (RCC) under intercropping. In general, common bean genotypes used in this study were highly affected by the  competition imposed by maize, indicating the need for further research to develop more compatible varieties of component crops and adjust the time of  common bean intercropping with maize

Combining Ability of Lowland Adapted Ethiopian Sorghum Hybrids for Yield

AbstractThis study was conducted with the objective to assess the performances of hybridsdeveloped from early and medium maturing lowland adapted Ethiopian sorghuminbred lines. A total of 95 hybrids and three checks were tested using alpha lettucedesign with two replications at Meiso and Sheraro. All agronomic practices weredone on time as recommended. Based on the results obtained from the analysispositive and significant GCA values among the female lines were recorded byICSV96143, ICSR93034, IESV92168-DC and ETSL101565. Likewise, testerTX623A were identified as most promising parents having good generalcombining ability for grain yield and almost all its major yield components.Similarly, for grain yield, 15 hybrid combinations had significant advantage overtheir respective standard check Melkam. Among these hybrids the highest wasobtained from MARC6A x IESV23010DL (78%) followed by TX623A xETSL101859 (71%) and TX623A x ETSL100684 (67%). The information generatedfrom the present study can be used for breeders who want to improve yield andyield-contributing traits of sorghum by understanding the genetic relationshipamong inbred lines

Combining ability and heterotic relationships between CIMMYT and Ethiopian maize inbred lines

Knowledge of combining ability and heterotic relation of exotic inbred lines with the locally available ones would be helpful for efficient breeding program. The objectives of the current study were to estimate: (i) combining ability effects between Ethiopian and CIMMYT (International Centre for Maize and Wheat Improvement) maize inbred lines and (ii) possible heterotic relationships between the two sources of inbred lines. Forty-two crosses were produced using North Carolina Design II mating scheme by crossing six Ethiopian with seven CIMMYT inbred lines. Combined analyses over three locations showed significant differences among the hybrids for all the studied traits. Both general (GCA) and specific (SCA) effects were significant for most traits, indicating the importance of both additive and non-additive effects for these traits. Female parents E2 and E4 showed significant and positive GCA effects for grain yield. Other female lines that showed desirable GCA effects were E1 for ear height, E2 for days to anthesis, ear and plant heights and E5 for days to anthesis and silkng. Among male parents, C1 was the best general combiner for all agronomic traits, but not for grain yield. Inbred lines C2 and C6 were good general combiners for plant height and days to silking, respectively. Hybrids E4 x C2 and E5 x C3 showed superior SCA effects for grain yield while few other combinations showed desirable SCA effects for days to anthesis, ear and plant heights. The results of this study indicated potential heterotic relationships between CIMMYT and Ethiopian inbred lines for use in hybrid and synthetic development and introgression of germplasm

Maize Lethal Necrosis Disease in Ethiopia: A Newly Emerging Threat to Maize Production

The occurrence of maize lethal necrosis (MLN) disease in Ethiopia was first reported in 2014. Thereafter, consecutive surveys were carried out in all majormaize growing areas across the country to understand the levels of distribution and incidence as well as potential alternate hosts of the disease.  Symptomatology was used to determine the incidence and level of damage caused by MLN at the field level. Samples of maize plants and alternative  grass hosts showing MLN symptoms were collected in all areas surveyed. Viruses associated with the symptoms were diagnosed in the laboratory using  Enzyme-Linked Immunosorbent Assay (ELISA), Lateral Flow Assay (LFA), Real Time-Polymerase Chain Reaction (RT-PCR), Multiplex RT-PCR, and RT-PCR  using porous ceramic cube. The results showed a wider distribution of MLN in Ethiopia with incidence levels reaching as high as 100% in some areas.  Maize planted during the off-season were found to be severely affected by MLN as compared to the main season crop. In addition to maize, MLN viruses  were found to infect various grass species indicating the presence of alternate hosts. This study confirmed seed transmission of MLN disease, but  variable rates of transmission were observed that needs to be studied further. Considering the current rate of MLN disease distribution in Ethiopia,  necessary management strategies should be devised and implemented before the disease causes significant damage to maize production.&nbsp

Identification of genomic regions associated with agronomic and disease resistance traits in a large set of multiple DH populations

Breeding maize lines with the improved level of desired agronomic traits under optimum and drought conditions as well as increased levels of resistance to several diseases such as maize lethal necrosis (MLN) is one of the most sustainable approaches for the sub-Saharan African region. In this study, 879 doubled haploid (DH) lines derived from 26 biparental populations were evaluated under artificial inoculation of MLN, as well as under well-watered (WW) and water-stressed (WS) conditions for grain yield and other agronomic traits. All DH lines were used for analyses of genotypic variability, association studies, and genomic predictions for the grain yield and other yield-related traits. Genome-wide association study (GWAS) using a mixed linear FarmCPU model identified SNPs associated with the studied traits i.e., about seven and eight SNPs for the grain yield; 16 and 12 for anthesis date; seven and eight for anthesis silking interval; 14 and 5 for both ear and plant height; and 15 and 5 for moisture under both WW and WS environments, respectively. Similarly, about 13 and 11 SNPs associated with gray leaf spot and turcicum leaf blight were identified. Eleven SNPs associated with senescence under WS management that had depicted drought-stress-tolerant QTLs were identified. Under MLN artificial inoculation, a total of 12 and 10 SNPs associated with MLN disease severity and AUDPC traits, respectively, were identified. Genomic prediction under WW, WS, and MLN disease artificial inoculation revealed moderate-to-high prediction accuracy. The findings of this study provide useful information on understanding the genetic basis for the MLN resistance, grain yield, and other agronomic traits under MLN artificial inoculation, WW, and WS conditions. Therefore, the obtained information can be used for further validation and developing functional molecular markers for marker-assisted selection and for implementing genomic prediction to develop superior elite lines

Factors that transformed maize productivity in Ethiopia

Published online: 26 July 2015Maize became increasingly important in the food security of Ethiopia following the major drought and famine that occurred in 1984. More than 9 million smallholder house- holds, more than for any other crop in the country, grow maize in Ethiopia at present. Ethiopia has doubled its maize produc- tivity and production in less than two decades. The yield, currently estimated at >3 metric tons/ha, is the second highest in Sub-Saharan Africa, after South Africa; yield gains for Ethiopia grew at an annual rate of 68 kg/ha between 1990 and 2013, only second to South Africa and greater than Mexico, China, or India. The maize area covered by improved varieties in Ethiopia grew from 14 % in 2004 to 40 % in 2013, and the application rate of mineral fertilizers from 16 to 34 kg/ ha during the same period. Ethiopia ’ s extension worker to farmer ratio is 1:476, compared to 1:1000 for Kenya, 1:1603 for Malawi and 1:2500 for Tanzania. Increased use of im- proved maize varieties and mineral fertilizers, coupled with increased extension services and the absence of devastating droughts are the key factors promoting the accelerated growth in maize productivity in Ethiopia. Ethiopia took a homegrown solutions approach to the research and development of its maize and other commodities. The lesson from Ethiopia ’ s experience with maize is that sustained investment in agricul- tural research and development and policy support by the national government are crucial for continued growth of agricultur

Genetic trends in CIMMYT’s tropical maize breeding pipelines

Fostering a culture of continuous improvement through regular monitoring of genetic trends in breeding pipelines is essential to improve efficiency and increase accountability. This is the first global study to estimate genetic trends across the International Maize and Wheat Improvement Center (CIMMYT) tropical maize breeding pipelines in eastern and southern Africa (ESA), South Asia, and Latin America over the past decade. Data from a total of 4152 advanced breeding trials and 34,813 entries, conducted at 1331 locations in 28 countries globally, were used for this study. Genetic trends for grain yield reached up to 138 kg ha−1 yr−1 in ESA, 118 kg ha−1 yr−1 South Asia and 143 kg ha−1 yr−1 in Latin America. Genetic trend was, in part, related to the extent of deployment of new breeding tools in each pipeline, strength of an extensive phenotyping network, and funding stability. Over the past decade, CIMMYT’s breeding pipelines have significantly evolved, incorporating new tools/technologies to increase selection accuracy and intensity, while reducing cycle time. The first pipeline, Eastern Africa Product Profile 1a (EA-PP1a), to implement marker-assisted forward-breeding for resistance to key diseases, coupled with rapid-cycle genomic selection for drought, recorded a genetic trend of 2.46% per year highlighting the potential for deploying new tools/technologies to increase genetic gain