Combing ability analysis of among early generation maize inbred lines

Combining ability estimates are important genetic attributes ina maize breeding program aiming to develop stable andhigh yielding hybrids and synthetic varieties. The objectives of this study were to estimate combining ability effects of locally developed and introduced early generation maize inbred lines for grain yield, yield related traits, and reaction to gray leaf spot (GLS) and northern corn leaf blight (NCLB) diseases; and (2) identify promising hybridsthat could be used in the breeding programs or for commercial production. Twenty-nine early generation maize inbred lines were crossed to two testers(SC22 and Guto-LMS5) using line xtester mating design. The resulting F1 progenies along with two check hybrids were tested across three locations (Hawassa, Arekaand Bako) in Ethiopia. Analysis of variance revealed significant difference among the hybrids for all studied traits. General combining ability (GCA) and specific combining ability (SCA) effects were also significant, indicating the contributions of both additive and non-additive gene actionsin controlling the traits studied. However, the relative magnitudes of GCA and SCA sum of squares indicated the preponderance of additive gene effects for all characters studied. Parental lines 2, 8, 9, 15 and 20 showed significantly positive GCA effects for grain yield. For GLS parents 1,7,23, and 26, and for TLB parents 5, 6and 7 revealed significantly negative GCA effects. These inbredlines couldbe good sources ofgenes for the improvement of the traitsunder considerationin the breeding programs.Five crosses, namely,L5 x GuttoLMS5,L7x Gutto LMS5, L8 x Guto LMS5, L15 x SC22 and L20 x TSC22) gave significantly higher grain yield advantage over the two standard checks. Further evaluation of these crosses can give reliable information about their performances to recommend the crossesfor commercial production

Genotype x environment interaction and stability analysis of grain yield in QPM hybrid varieties

Maize (Zea mays L.) is a major staple cereal widely cultivated in different agro-climatic environments of Ethiopia.Maize productivity in the tropical highland region of the country is known by low average yield mainly due to thelack of high yielding and widely adapted improved cultivars. The objectives of this study were to determine G×Einteraction and yield stability of quality protein maize (QPM) experimental hybrids,to identify ideal genotype withhigh average yield depending on the differential genotypic responses to environment, and to form homogeneousgrouping of environments. The study was conducted at seven environments representing the tropical-highlandsub-humid maize growing agro-ecology of Ethiopia in 2015/2016. Thirty-three QPM hybrids and three-commercial hybridchecks were evaluated using a 4 ×9 alpha lattice design. Yield data was analyzed using AMMI and GGEbi-plot methods. Using AMMI analysis, four promising QPM hybrids designated asG31, G7, G19, G29, and G22were identified based on combined stability and average yield.GGEbi-plot displayed that variety Jibatwas closestto the ideal genotype, can be considered as best hybrid whereas G29, G22 were considered as desirably stable genotypes.GGE bi-plot also displayed Holeta as ideal environment and thus considered useful in discriminating thehybrids and representativeness as suitable environment. The GGE analysis delineated the test environments intothree mega-environments useful for targeted evaluation of genotypes. The result of this study indicated specificallyand widely adapted high yielding stable genotypes and also revealed homogeneous test environments

Mega-Environment Targeting of Maize Varieties using Ammi and GGE Bi-Plot Analysis in Ethiopia

አህፅሮት በቆሎ በኢትዮጵያ  ከሚመረቱ የምግብ ሰብሎች መካከል በምርትና ምርታማነቱ ግንባር ቀደም ስፍራን የያዘ ሰብል ነው፡፡  የሰብሉን ምርታማነት ከሚደግፉ የተለያዩ መንስዔዎች  ውስጥ በዋናነት ከፍተኛውን  ቦታ  የሚይዙት ከጥናትና ምርምር  የተገኙ የተሻሻሉ ዝርያዎች ቢሆኑም ሁሉም ዝርያዎች   በበቆሎ አብቃይ ስነ-ምህዳሮች  ላይ ተዘርተው  በምርታማነታቸው ወጥነት የማያሳዩ መሆናቸው ይታወቃል፡፡ እንደየአካባቢው የአይር ፀባይ፤ የአፈር ዓይነትና የዝናብ መጠን እንዲሁም የመሬት ከባህር ወለል ከፍታ ልዩነት የተነሳ በምርታማነታቸው ለየአካባቢው ተመራጭና ተመራጭ ያልሆኑ ዝርያዎችን መለየት ይቻላል፡፡ በዚህ ምክንያት ለተለያዩ ዝርያዎች ምርታማነት ተስማሚና ወካይ የሆኑ ስፍራዎችን  ለይቶ በማወቅ የትኛው ዝርያ በየትኛው ስፍራ ላይ ቢዘራ  ሁለንተናዊ የአካባቢ ባህሪያትን  ተላብሶ ከፍተኛ ምርት ሊሰጥ ይችላል?  እንዲሁም የትኛቹ ስፍራዎች በአየር ንብረት ተቀራራቢነት በጥቅል ተደምረው አንድ ዝርያ በወጥነት  በሁሉም ስፍራ ተዘርቶ ምርታማ የሚያደርጋቸውን አካባቢዎች ለይቶ ለማወቅ ጥናቱ ተደረገ፡፡ ጥናቱ ለምርት በምርምር የተለቀቁ  19 ዲቃላ የበቆሎ ዝርያዎችን በማካተት  ወይናደጋማና ደጋማ ስፍራዎች ላይ ተዘርተው የተለያዩ መረጃዎችን  በማሰባሰብ እንዲጠናቀር ከተደረገ በኋላ ለጥናቱ ስኬት   ከፍተኛ ትኩረት ተሰጥቶት  ለውሳኔ  እንዲያመች ከየአካባቢው የተሰበሰቡ የዝርያዎቹ ምርት አግባብ ባላቸው ሳይንሳዊ ዘዴዎች እንዲሰሉ ተደረገ፡፡ በስሌቱ መሰረት ከዝርያዎቹ በአማካይ በሔክታር 4.47 ( BH545)  እስከ 7.49  ( BH546) ቶን  ምርት ተመዘገበ፡፡ እንዲሁም በተደረገው ስሌት G14  እና  G1  ተብለው የተለዩ ዝርያዎች ለአብዛኞቹ የጥናቱ ስፍራዎች ተስማሚ  እንደሆኑ  ቢታወቅም  BH546  በሚባል ስያሜ የሚለየው ዝርያ በከፍተኛ ደረጃ ተመራጭ እንደሆነ ለማረጋገጥ ተችለሏል፡፡ በሌላ በኩል E9  በተባለ ምህፃረ-ቃል የሚለይ ስፍራ በአብዛኛው ዝርያዎች  ተመራጭ እንደሆነ ስሌቱ ሲያሳይ ፤ E1  የተባለው ግን ተመራጭ እንዳልሆነ ታውቋል፡፡ ሆኖም ግን 11 የጥናት ስፍራዎች በሶስት ዋና ዋና ፤ እያንዳንዳቸው በዝርዎቹ ምርታማነት የጎላ ልዩነት በሚታይባቸው ወጥ ክፍሎች እንደተከፈሉ የስሌቱ ውጤት ለይቶ አሳይቷል፡፡ በዚህ መሰረት E9 በሚል ስያሜ የሚለየው ስፍራ በብቸኝንት እንደ አንድ ዋና ክፍል የተከፈለ ሲሆን በሁለተኛ  ክፍል ውስጥ  በጥቅል  ዘጠኝ  አካባቦዎች  E1, E2, E3, E5, E6, E7, E8  እና E11  በአንድነት ተደመሩ፤ እንዲሁም  E4 እና  E10 በሶስተኛው ክፍል ውስጥ ተመደቡ፡፡ E3, E5 and, E7 በተባሉ ምህፃረ-ቃል የተለዩ ስፍራዎች ለዝርዎቹ ምርታማነት ወካይና ተመራጭ መሆናቸውን ጥናቱ አሳየ፡፡  ነገር ግን E4, E9 and E10  የተባሉ አካባቢዎች በውስን ስፍራዎች ውስጥ  ምርታማ የሚሆኑ  ዝርያዎችን መለየት የሚችሉ መሆናቸውን ጥናቱ ያረጋግጣል፡፡  በሌላ በኩል E8 and E11 የተባሉ ስፍራዎች የዝርያዎችን ምርታማነትና ተመራጭነት  በጉልህ ለማሳየት ምንም አስተዋፅዖ ያላበረከቱ መሆናቸውን ጥናቱ አሳይቷል፡፡ በመጨረሻም የዚህ ጥናት ውጤት ወጥነት ያላቸው ሶስት ዋና ዋና ስነ-ምህዳራትን ለይቷል፤  ዝርይዎች በምርታማነታቸው   ተመራጭነት  የሚኖራቸውንና  የማይኖራቸውነ  ለይተው የሚያሳዩ ስፍራዎችን  ጠቁሟል እንዲሁም በምርታማነቱና ለአብዛኛው አካባቢዎች  በወጥነት ተስማሚነቱን የሜያሳይ ዝርያ ለይቶ አሳይቷል፡፡ Abstract In multi-location experimental trials, test locations must be selected to properly discriminate between varieties and to be representative of the target regions. The objective of this study were to evaluate test locations in terms of discrimination ability, representativeness, and desirability, and to investigate the presence of mega-environments using AMMI and GGE models and to suggest representative environments for breeding and variety testing purposes.  Among 19 maize varieties tested across 11 environments, mean grain yield ranged between 4.47 t/ha (BH545) to 7.49 t/ha (BH546). Both AMMI and GGE  models identified   G14 and G1 as  desirable hybrids for cultivation   because they combined stability and higher average yield. Nonetheless, as confirmed by GGE analysis BH546 was most closest to the ideal genotype hence, considered as best hybrid.  Environment wise, E9 and E4 were the most stable and unstable test environments, respectively. The 11 test environments fell into three apparent mega-environments.  E9 formed one group by its own, E1, E2, E3, E5, E6, E7, E8 and E11 formed the second group and E4 and E10 formed the third group.  E3, E5 and, E7 were both discriminating and representative therefore are favorable environments for selecting generally adapted genotypes. E4, E9 and E10 were discriminating but non-representative test environments thus are useful for selecting specifically adapted genotypes. E8 and E11 were non-discriminating test environments hence little information about the genotypes. The results of this study helped to identify mega-environments, also representativeness and discriminating power of test environments better visualized with the GGE bi-plot model

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

Combining ability and heterotic orientation of mid-altitude sub-humid tropical maize inbred lines for grain yield and related traits

Information on the combining ability and heterotic pattern of elite inbred lines is essential to maximize their use in hybrid maize development. This study was conducted to determine combining ability and heterotic pattern of locally developed maize inbred lines for grain yield and related traits. Seventeen inbred lines (10 female inbred lines and 7 tester inbred lines) were used to generate 70 single cross hybrids using line by tester crossing scheme. The resulting 70 cross progenies plus two standard checks arranged in 8×9 alpha lattice design replicated twice were planted at three mid-altitude sub-humid testing sites in Ethiopia (Bako, Hawassa and Pawe) in 2011 main cropping season. The combined analysis of variance for yield and other related traits showed highly significant differences among genotypes, crosses, female inbred lines (General combining ability, GCA), tester inbred lines (GCA), line x tester (Specific combining ability, SCA); and the interactions of these source of variation with the environment for all traits studied except for ear aspect (EA) and grain yield (GY) in female inbred lines (GCA), EA in inbred line testers (GCA) and for days to anthesis (AD) in line x tester (SCA) x environment. The significance of both GCA (lines and testers) and SCA of LxT for AD, days to silking (DS), plant height (PH), ear height (EH), EA and GY showed that both additive and non-additive gene actions are important in controlling these traits. Furthermore, the proportion of GCA sum of squares were greater than the SCA sum of squares for AD, DS, PH, EH, and EA indicating the predominance of additive gene actions in controlling these traits. For GY, the ratio of GCA to SCA sum of squares was near to unity indicating both additive and non-additive gene actions were equally important. This study identified inbred lines that can make good cross combination for more than one trait. L1 was found to be good combiner for lower values of AD, DS, PH and EH indicating that this line could be used in improving maize for earliness and short stature. L4 was ideal parent for reducing AD and DS. L3 was found to be good combiner for GY and other related traits. In addition, lines were grouped into heterotic group A, B or AB based on SCA. Based on its per se performance and combining ability, L3 was proposed to be used as a tester in heterotic group B. This study also validated T5 remain to be used as a tester in heterotic group A. Based on the SCA of crosses, heterosis and per se performance of the parents, five best cross combinations were identified for possible release or for use as parents of three way hybrids. Further verification of the stability of the selected hybrids and the new proposed tester across more locations needs to be done

Test cross performance and combining ability of newly introduced quality protein maize (Zea mays) inbred lines for grain yield and agronomic traits evaluated in mid-altitude agro-ecological zones of Ethiopia

Development of quality protein maize (QPM) helps to reduce human malnutrition in areas where maize is the major protein source in the diet. The objective of this study was to estimate combining ability effects of QPM inbred lines for grain yield and yield-related traits. Twenty-one newly introduced QPM inbred lines were crossed with four single cross testers in a line × tester mating design and resulted in 84 F1 progenies. These F1 hybrids, including four checks, were evaluated in an 8 × 11 alpha lattice design with two replications at four locations during 2016. Mean squares due to location, crosses, general combining ability (GCA) and specific combining ability (SCA) were significant for most traits. However, the contributions of GCA sum of squares to the variation among the hybrids were larger than SCA sum of squares, suggesting that the traits were controlled predominantly by additive gene effects. Among the inbred lines, L3, L5 and L10 showed positive and significant GCA effects for grain yield and other agronomic traits. The lines can be used in synthetic variety development. Among crosses, only L3 × T3, L9 × T1 and L15 × T2 revealed positive and significant SCA effects for grain yield, implying the presence of heterosis in these particular crosses

Fast-Tracking the Development and Dissemination of a Drought-Tolerant Maize Variety in Ethiopia in Response to the Risks of Climate Change

Climate change projections suggest increased frequency of drought in many parts of sub-Saharan Africa (SSA). The replacement of old varieties of maize with new drought-tolerant (DT) varieties will be crucial to respond to the future risk of drought, as it already is today. The first group of locally developed maize hybrids in Ethiopia—BH140, BH660 and BH540—were commercialised between 1988 and 1995, but were not selected for drought tolerance. Among these, BH660 remained the most popular and widely grown maize variety in the Ethiopian maize belt between 2000 and 2010, accounting for nearly 50% of maize area under improved seed. A new DT hybrid, BH661, with better agronomic performances under optimum and random drought than BH660, was identified and released in 2011. In 2016, 9000 tonnes of certified seed—enough to plant 360,000 ha—was produced and marketed. The concerted effort of breeders and seed producers as well as governmental and non-governmental extension workers drove the development, release and rapid adoption of BH661 contributing to food and income security of more than 300,000 households by mitigating the effects of climate change in Ethiopia. The success of BH661 is a valuable and timely case study for breeders, seed companies, extension agents, regulatory bodies and policy-makers striving to develop and disseminate new DT varieties in sub-Saharan Africa

Additional file 4: of Genetic variation and population structure of maize inbred lines adapted to the mid-altitude sub-humid maize agro-ecology of Ethiopia using single nucleotide polymorphic (SNP) markers

Heat map of the 265 inbred lines based on relative kinship matrix estimated from 220,878 polymorphic SNPs. (DOCX 211 kb