Background: Maize (Zea mays L.) plays a critical role in meeting high food demand. It is globally one of the most widely adapted and cultivated crops. Hybrid development from fixed inbred lines is one of the strategies for the improvement of maize production. The national average maize yield in Ethiopia is low and thus, selection of promising germplasm and knowledge of combining ability are prerequisites to developing high yielding maize varieties. Forty-two Quality Protein Maize (QPM) crosses (21 inbred lines each crossed with two testers) along with three popular standard hybrids were evaluated in two replications using alpha lattice during the 2017 cropping season at Ambo, Arsi-Negele, and Kulumsa. The objectives of this study were to identify lines with high GCA and estimate the SCA of crosses for grain yield, and other agronomic and morphological characters. Results: Significant difference among crosses was observed for 19 traits at Ambo, 14 traits at Arsi-Negele, and 19 traits at Kulumsa in the hybrid trial. Regarding the GCA effect, L8 had a significant difference to the positive side with the highest magnitude of GCA effect at three locations (3.40, 2.03, and 1.88 GCA effect values at Arsi-Negele, Ambo, and Kulumsa, respectively) which is followed by L7 for GY. All crosses did not show a significant SCA effect for GY in both directions at Ambo and Arsi-Negele but at Kulumsa, five crosses: L2xT1(1.89), L13xT2(1.88), L7xT1(1.86), L4xT2(1.49) and L19xT1(1.41) showed significant difference. In the combined analysis for six traits, Additive gene action was more important which was manifested by a higher sum square contribution of DS (79.6) EPP (79.3%), EL (80.0%), KPR (80.1%), ED (78.5%) and TSW (79.1%). Conclusion: Based on mean grain yield, and combining ability, L8xT2, L7xT1, L8xT1, L19xT1, L6xT2, and L18xT1 are promising crosses that could be forwarded for further use in maize breeding programs for further works.

Background: Maize plays an indispensable role in meeting high food demand. It is globally one of the most widely adopted and cultivated crops. Hybrid development from fixed inbred lines is one of the strategies for the improvement of maize production. The national average maize yield is low in East Africa; thus, the selection of promising germplasm has a great role to meet the high food demand of growing the population.  Forty-two Quality Protein Maize (QPM) crosses (21 inbred lines each crossed with two testers) along with three popular standard hybrids checks were evaluated in two replications using alpha lattice during the 2017 cropping season at Ambo, Arsi-Negele, and Kulumsa. The objective of this study was to evaluate and select the best new QPM hybrids for grain yield, and other agronomic and morphological characteristics. Results: Significant difference among crosses was observed for 19 traits at Ambo, 14 traits at Arsi-Negele, and 19 traits at Kulumsa.  Out of 28 traits studied, six of them did not show genotype by location interaction but they showed a significant genotypic effect. These traits were: Days to Silking (DS), Number of Ears per plant (EPP), Ear Length (EL), Kernels Per Row (KPR), Ear Diameter (ED), and Thousand Seed Weight (TSW).  Based on the mean performance in the combined analysis, from 42 new QPM crosse, six of them (L8xT2, L7xT1, L8xT1, L19xT1, L6xT2, and L18xT1) were scored higher grain yield compared with the mean of the three standard checks and best conventional maize (CM) check (AMH853). L8xT2, L7xT1, L8xT1 crosses showed a higher grain yield advantage over the best check (AMH853) by 20.87, 14.13, and 13.63%, respectively. Conclusion: The study implicated the existence of a difference between the newly developed hybrids and the standard check varieties. In general, the study enabled us to identify promising crosses that could be forwarded for further use in maize breeding programs in future work.

Screening of maize genotypes under different cropping systems (sole and inter cropping) is very important to understand the genotypes response for different abiotic and a biotic stress. Nine maize genotypes including the standard check (BH-543) were planted and evaluated at research and farmers' fields in the 2011 and 2012 cropping seasons. Farmers were invited to evaluate the genotypes based on their criteria of selection. Hawassa-Dume common bean variety was used for intercropping purpose in 2012. The genotypes substantially varied for yield and other traits both under sole and intercropping systems. When combined across seasons, the high yielding genotypes, genotype-1 and genotype-5 showed 38 and 37% yield advantage over the standard check. Besides, genotypes markedly varied for their compatibility for intercropping system with land equivalent ratio (LER) <1 for most of genotypes. However, genotype-4 and genotype-8 had LER >1 highlighting the need to evaluate genotypes for intercropping system at early stage of breeding.

Determination of heterosis in maize hybrids is necessary for the identification of superior F1 hybrids for breeding programs. Therefore, this study was conducted to estimate the amount of mid parent (MPH) and better parent heterosis (BPH) for grain yield, yield-related, agronomic, and morphological traits. Hybrid development from fixed inbred lines is one of the strategies for the improvement of maize production. The national average maize yield in Ethiopia is low and thus, selection of promising germplasm, knowledge of combining ability, and heterotic grouping are prerequisites to developing high-yielding maize varieties. Forty-two Quality Protein Maize (QPM) crosses (21 inbred lines each crossed with two testers) along with three popular standard hybrids were evaluated in two replications using alpha lattice during the 2017 cropping season at Ambo and, Arsi-Negele. Parental line trials consisting of 21 lines, two testers, and one conventional maize (CM) parent check (FS67) were established in two replications laid out using RCBD side by side with the hybrid trials at Ambo and Arsi-Negele. At Ambo, almost all crosses showed positive and significant BPH except three crosses (L1xT1, L4xT1, and L13xT1). The maximum BPH (276.2%) was obtained from L17xT2. Similarly, at Arsi-Negele, most of the crosses had positive and significant BPH except for five crosses for BPH which are showing negative heterosis. The highest BPH was obtained from L10xT2 at Arsi-Negele. Generally, the high yielding crosses had reasonable BPH. Based on the result promising crosses and lines were identified. Some of the crosses showed good performance in terms of heterosis against the mid parent and better parent: L17xT2 (329.88% MPH, 276.18% BPH), L3xT2(320.05% MPH, 273.91%BPH), and L19xT2(2802.57% MPH, 247.31% BPH) at Ambo, whereas at Arsi-Negele L10xT2 (128.38% MPH, 111.27%BPH) and L11xT2(115.33% MPH, 98.00% BPH) showed the higher heterosis compared with the mid parent and better parent. Crosses that showed best yield performance were: L8xT2, L7xT1, L8xT1, L19xT1, L6xT2, and L18xT1. These crosses should be reconsidered for further evaluation and possible release.

Background: Maize plays a critical role in meeting high food demand. It is a globally widely adopted and cultivated crop. Hybrid and open-pollinated varieties development from fixed inbred lines is one of the strategies for the improvement of maize production. Compared with the world average, the national average maize yield is low in Ethiopia. According to this development and selection of promising germplasm has indispensable value for developing high-yielding maize varieties. The study consists of 21Quality Protein Maize (QPM) lines, two QPM testers lines, and one Conventional Maize (CM) line check (FS67). They were evaluated in RCBD with two replications at Ambo and Arsi-Negele. The objective was to identify new lines with good performance compared with released QPM checks and CM lines. Results: There is a significant difference between the lines for 28 traits in Ambo and 24 traits at Arsi-Negele. In combined mean performance analysis, the highest yielding line (L8) exceeded the mean of all line checks, mean QPM checks, CM line check (FS67), and best QPM line check (CML144) by 34.89%, 54.80%, 7.30%, and 25.31%, respectively for GY. The value of EPP ranged from 0.91 (L14) to 1.85 (L3) with an overall mean of 1.19). The highest yielding line (L8) had the 2nd highest EPP (1.63). Mean EPP of the top five QPM lines was less by 5.45%, 4.96%, 22.41%, and 6.41% compared with the mean of all checks, mean of QPM line checks, best QPM check, and CM line check, respectively. The high yielder line (L8) had a higher mean value than the mean of lines checks (CML144, CML159, and FS67), mean of QPM lines checks, best QPM check (CML144), and FS67 by 25.71%, 26.36%, 3.16%, and 24.43%, respectively. Conclusion: In general, the study confirmed the existence of promising new QPM parental lines. These promising lines can be used as source material in the breeding program for further improvement.

Maize plays an indispensable role in meeting high food demand. It is globally one of the most widely adopted and cultivated crops. Hybrid development from fixed inbred lines is one of the tactics to boost maize production. The national average maize yield in Ethiopia is low and thus, selection of promising germplasm, knowledge of combining ability, and heterotic grouping are prerequisites to develop high-yielding maize varieties. Forty-two Quality Protein Maize (QPM) single crosses (21 inbred lines each crossed with two testers) along with three popular standard hybrid checks were evaluated in two replications using alpha lattice design during the 2017 cropping season at Ambo, Arsi-Negele, and Kulumsa. The objective of this study was to estimate standard heterosis for grain yield (GY), and other agronomic and morphological characters. Significant difference among crosses was observed for 19 traits at Ambo, 14 traits at Arsi-Negele, and 19 traits at Kulumsa in the hybrid trial.  For GY, at Ambo, almost all crosses showed negative heterosis against the best check (AMH853). At Arsi-Negele 14 crosses had positive standard heterosis, from these only three crosses: L8xT1 (50.8%), L8xT2 (46.6%), and L7xT1 (33.9%) showed significant difference against Jibat but at Kulumsa, the difference for standard heterosis was positive but non-significant only by two crosses: (L7xT1 (6.6%) and L19xT1 (4.7%). Based on mean grain yield and standard heterosis, L8xT2, L7xT1, L8xT1, L19xT1, L6xT2, and L18xT1 are promising. The study of the results highlighted that the breeding program was successful in generating superior QPM hybrids. Based on the finding we suggest that it is better to use the parents of theses hybrids as potential source materials in the breeding program through to form different crosses formation.

Cereal crops especially maize production in Ethiopian Central Rift Valley is affected by biotic and abiotic production. This study was conducted for two seasons (2015-2016) and the best cropping system was identified using Randomized Complete Block Design with three replications. The experiment had six treatments (1) Continuous mono-cropping under conventional practice (CN), (2) continuous mono cropping under conservation agriculture (CA) (3) relay cropping (CA) with double bean planting within a season (maize bean inter-cropping: second round bean planting was conducted after immediate harvesting of the first bean), (4) Double cropping (CA) (maize bean inter cropping after sole lablab), (5) Double cropping (CA) (maize after bean) and (6) Double cropping (CA) (bean after maize). In 2016, the highest maize biomass yield and maximum water use efficiency were obtained from double cropping bean after maize with value of 16050 kg/ha and 31 kg mm -1 , respectively. Maize-bean relay cropping outperformed the sole maize under CA and CN by 182 and 138% for maize grain yield. Water use efficiency of double cropping (maize after bean) and relay cropping was higher than double cropping (bean after maize) by 366 and 197% in 2015 for maize grain yield. For biomass, relay cropping under CA and sole maize under CN had similar water use efficiency of 18 kg mm-1 . The CA practice with diverse crops planted together: double inter-cropping at different time (relay cropping) and double cropping under CA are good options for using the residual soil moisture and to sustainably improve crop productivity.

Efforts to boost maize productivity can be undertaken through systematic management of heterosis. Combining ability test is a critical step towards identifying a heterotic group of new parental lines. Different heterotic grouping methods has been used by different researchers. Among these, SCA and hybrid mean, hybrid index, combined use of amplified fragment length polymorphism (AFLP), SSR markers and heterotic group's specific and general combining ability (HSGCA) are the major grouping methods. This study aimed to (i) assign maize inbred lines into heterotic groups and (ii) compare efficiency of different grouping methods. An experiment with 21 maize inbred lines crossed to two testers with known heterotic groups was conducted in 2017. The hybrid and parent experiments were tested together and laid out side by side. This study identified good heterotic grouping procedure. The breeding efficiency of HSGCA was higher by 31.6, 11.0 and 9.6% over joint SCA and hybrid mean, SCA and hybrid index methods, respectively. While the hybrid index method was more efficient than joint SCA and hybrid mean and SCA by 20.1 and 1.3% respectively, the SCA grouping method was more efficient than joint SCA and hybrid mean method by 18.5%. The highest (37%) and lowest (28.1%) breeding efficiency value were scored by HSGCA and hybrid index heterotic grouping method, respectively. Based on the result, HSGCA grouping method was more efficient. The variable heterotic grouping of the 21 newly developed QPM lines in this study indicated that different heterotic grouping methods have different efficiency in grouping the germplasms.