Leaf senescence induced by nitrogen deficiency as indicator of genotypic differences in nitrogen efficiency in tropical maize     

Gunda Schulte auf'm Erley  Nazma Begum  Mosisa Worku  Marianne Bänziger  Walter J. Horst 《植物养料与土壤学杂志》2007,170(1):106-114

Nitrogen efficiency is a complex trait. Identification of secondary plant traits correlating with N efficiency would facilitate the breeding for N‐efficient cultivars. Sixteen tropical maize cultivars differing in grain yield at low N supply (N efficiency) under field conditions in Zimbabwe exhibited a significant negative correlation between N efficiency and leaf senescence during grain filling. The same cultivars were studied for leaf senescence under N deficiency in a short‐term nutrient‐solution experiment. Leaf chlorophyll contents as estimated by SPAD values and photosynthesis rates were used as measures for leaf senescence. Cultivars differed both in SPAD values and photosynthesis rates of the older leaves during N deprivation. Significant negative correlations were found between SPAD values, photosynthesis rates in the nutrient‐solution experiment, and leaf‐senescence scores in the field experiments, and positive correlations were found between photosynthesis rates and grain yield under low‐N conditions in the field. Relationships between physiological root parameters, which were also investigated in the nutrient‐solution experiment, and N uptake or grain yield of the cultivars in the field could not be established. It is concluded, that the assessment of the capacity of a genotype to maintain a higher photosynthetic capacity of older leaves during N deficiency–induced senescence at the seedling stage is a suitable selection parameter for the N efficiency of tropical maize cultivars.  相似文献   

Analysis of milk-derived isolates of E. coli indicating drug resistance in central Ethiopia     

Messele  Yohannes Equar  Abdi  Reta Duguma  Tegegne  Desiye Tesfaye  Bora  Shelema Kelbesa  Babura  Mosisa Dire  Emeru  Bezina Arega  Werid  Gebremeskel Mamu 《Tropical animal health and production》2019,51(3):661-667

Mastitis is one of the most important diseases in dairy cows throughout the world and is responsible for significant economic losses to the dairy industry. This study was performed to characterize the genetic basis of drug resistance in Escherichia coli isolated from cases of clinical and sub-clinical bovine mastitis. A total of 224 California mastitis test (CMT)-positive milk samples were collected from December 2015 to April 2016 to characterize the phenotypic and genetic basis of antimicrobial resistance in E. coli isolated from raw milk from dairy farms found in Burayu, Sebeta, and Holeta areas of Ethiopia. The prevalence of E. coli was 7.1% (16) and both phenotypic and molecular techniques were used to identify E. coli antimicrobial susceptibility trait. The most commonly observed phenotypic resistance was against ampicillin (68.7%), sulphamethazole-trimethoprim (50%), and streptomycin (25%). Multidrug resistance phenotypes were found in 11 of 16 (68.7%) of E. coli isolates. Tetracycline (tet (A)) and chloramphenicol (cml (A)) genes were the most predominant encoding resistance genes identified (50%) each, followed by gentamycin resistance encoding gene (aac (3)-IV) (37.5%). Overall, 11 (68.7%) of the isolates had multidrug resistance genes responsible to two or more classes of antibiotics. The most common pattern detected was cml (A) and tet (A) together 37.5% followed by aac (3)-IV and tet (A) 25%. The current study indicated that raw milk could be regarded as critical source of antibiotic-resistant pathogenic E. coli.

  相似文献   

Heterosis and combining ability of elite maize inbred lines under northern corn leaf blight disease prone environments of the mid-altitude tropics     

Wende Abera  Shimelis Hussein  John Derera  Mosisa Worku  Mark Laing 《Euphytica》2016,208(2):391-400

  相似文献   

Grain yield performance and flowering synchrony of CIMMYT’s tropical maize (Zea mays L.) parental inbred lines and single crosses     

Mosisa Worku  Dan Makumbi  Yoseph Beyene  Biswanath Das  Stephen Mugo  Kevin Pixley  Marianne Bänziger  Fidelis Owino  Michael Olsen  Godfrey Asea  Boddupalli M. Prasanna 《Euphytica》2016,211(3):395-409

  相似文献   

Genetic interrelationships among medium to late maturing tropical maize inbred lines using selected SSR markers     

Abera Wende  Hussein Shimelis  John Derera  Worku Mosisa  Jedidah Danson  Mark D. Laing 《Euphytica》2013,191(2):269-277

Understanding the genetic relationships among breeding lines is fundamental in crop improvement programs. The objectives of this study were to apply selected polymorphic single sequence repeat (SSR) DNA markers and cluster medium to late maturing tropical elite maize inbred lines for effective hybrid breeding. Twenty elite inbred lines were genotyped with 20 SSR markers. The analysis detected a total of 108 alleles. The unweighted pair group method with arithmetic mean allocated the inbred lines into five clusters consistent with the known pedigrees. The tested inbred lines that were adapted to mid-altitude, sub-humid agro-ecologies were classified in different clusters, except for a few discrepancies. The greatest genetic distance was identified between the clusters of lines CML-202 and Gibe-1-91-1-1-1-1. The analysis determined the genetic grouping present in the source population, which will assist in effective utilization of the lines in tropical hybrid maize breeding programs to exploit heterosis.  相似文献