Phosphorus Use Efficiency of Common Bean Cultivars in Ethiopia

Phosphorus (P) deficiency in the soil is one of the major factors limiting common bean production in Ethiopia. A pot experiment was conducted in a glasshouse at Hawassa University in southern Ethiopia to evaluate twelve common bean cultivars for P use efficiency at three phosphorus rates (0, 120, and 240 kg P₂O₅ ha^?1). The results of the study revealed that the interaction effect of cultivar and P rates significantly (P < 0.01) influenced grain yield efficiency index (GYEI), grain yield and yield attributing traits, leaf P concentration, root length, diameter and surface area. Grain yield efficiency index at low and medium phosphorus rates indicated that Red-Wolaita, Dinkinesh, Tabour, Nasir and Haramaya are P-efficient, whereas Chore was found to be P-inefficient. These genotypic variations could be exploited for sustainable production of the crop by fitting suitable varieties to soils with variable P availability. Thus, the P-efficient cultivars indicated above could be recommended for cultivation by smallholder farmers in soil with low P availability that is dominant in the study area.     

Identification of resistance genes to Puccinia striiformis in seedlings of Ethiopian and CIMMYT bread wheat varieties and lines

In a controlled environment, the reaction was observed of 42 bread wheat varieties and lines inoculated with 19 isolates of yellow rust differing in their virulence to 20 differential varieties. Five varieties and lines showed resistance to all isolates. The remaining ones appeared to have the genesYr2, Yr3, Yr4, Yr6, Yr7, Yr9 andYrA, either singly or in combination.Yr9 derived from rye was present in 67% of the varieties and lines.Yr4 is the only effective gene in that material as, in Eastern and Central Africa, yellow rust has virulence to the otherYr genes. Recognition of virulence toYr genes is enhanced by the use of a supplemental set of differential varieties supposedly carrying a single gene.Samenvatting Onder geconditioneerde klimaatsomstandigheden zijn 42 Ethiopische en CIMMYT rassen en lijnen van broodtarwe (Triticum aestivum) in het kiemplantstadium geïnoculeerd met 19 isolaten van gele roest die onderling verschilden in hun pathogeniteit voor 20 differentiërende tarwerassen waarvan de resistantie-achtergrond bekend is. De genom-gen relatie is toegepast om resistentiegenen te identificeren. Vier rassen en lijnen bleken resistent te zijn tegen alle isolaten. Verondersteld wordt dat hun resistentie berust op genen die niet eerder herkend waren of op een combinatie van bekende genen die niet compatibel was met de gebruikte isolaten. In het overige tarwemateriaal kon de aanwezigheid worden aangegeven van de resistentiegenenYr2, Yr3, Yr4, Yr6, Yr7, Yr9 enYrA. Het van rogge afkomstige en door het CIMMYT veel gebruikte resistentiegenYr9 was in 28 rassen en lijnen (67%) aanwezig. In het onderzochte tarwemateriaal isYr4 het enige voor Oost en Centraal Afrika effectieve resistentiegen omdat de daar voorkomende gele roest pathogeniteit bezit voor de overige genen. Het herkennen van pathogeniteit van gele roest voor bepaalde resistentiegenen is verbeterd door het toevoegen van tarwerassen met monogene resistentie aan het internatinale gebruikte tarwesortiment voor de determinatie van gele-roestfysio's.     

Genotype × cropping system interaction in climbing beans (Phaseolus vulgaris L.) grown as sole crop and in association with maize (Zea mays L.)

The selection of cultivars for the predominant cropping systems of small farms in the tropics depends to a large extent on the information obtained by testing their performance across the different systems. The main objective of this experiment was to measure the genotype × cropping system (G × CS) interaction for yield and selected agronomic traits of climbing beans (Phaseolus vulgaris L.) grown as sole crop and intercropped with two morphologically contrasting maize (Zea mays L.) cultivars. A secondary objective was to identify the most efficient and productive bean–maize intercrop combinations. Seven climbing bean genotypes were grown as sole crop and intercropped with two maize varieties, BH 140 (Mix. 1) and Guto (Mix. 2), in a factorial arranged Randomized Complete Block Design with three replications at Bako Agricultural Research Center in western Ethiopia. Main effects due to genotype and cropping system (except days to flowering) were significant for all bean traits considered. The genotypes × cropping system interaction terms were also significant for the number of seeds per pod, 100-seed weight, harvest index and seed yield. While bean seed yield significantly correlated with the number of seeds per pod (in Mix. 1) and with harvest index (in both mixtures), positive and significant correlations occurred with the number of pods per plant and 100-seed weight under sole cropping system. The correlation between bean seed yields of Mix. 1 and Mix. 2 and between Mix. 2 and sole crop were positive and significant. No such relationship was found between Mix. 1 and sole crop. The results suggest that selection of suitable climbing bean cultivars for intercropping with maize varieties predominantly grown in the area should be made under the associated culture of the two crops. Intercropping contributed to a significant reduction in seed yield of the bean genotypes due mainly to its adverse effects on the numbers of pods per plant and seeds per pod. The index tLER₁ identified most bean–maize genotype combinations of Mix. 2 as biologically more efficient system than Mix. 1. On the other hand, tLER₂ values of more than 1.00 for all treatments of Mix. 2 demonstrated higher overall productivity of the intercrop system when the bean genotypes were grown in association with a late-maturing and high yielding maize hybrid BH 140.     

Calf survival and reproductive performance of Holstein–Friesian cows in central Ethiopia

This study was carried out to evaluate the reproductive performance and calves survival rate of Holstein–Friesian (HF) herd in Holeta, central highland of Ethiopia. A retrospective analysis of 26 years data was carried out, from which records of 724 age at first calving (AFC), 2,022 calving intervals (CI), 2,971 breeding efficiencies (BE), 260 abortions, 111 stillbirths were derived from 795 cows. Moreover, 738 female calves’ records were also included for survival rate study. The overall least squares means of AFC, CI, and BE were 40.9 ± 0.33 months, 475 ± 2.84 days, 81.9 ± 0.26%, respectively, while the incidence rates of abortion, stillbirth, and female calves survival rate for this herd were 8.0%, 3.4%, and 77.5%, respectively. The effects of parity number and year of birth/calving on CI and BE were significant (P < 0.001). Moreover, birth year had significant (P < 0.001) effect on AFC and calves survival rate, while calving season had significant effect on BE. The reproductive performance found in this study was lower than the performance reported in many tropical regions and the genetic potential of HF breed in their origins. Moreover, higher loss due to calf mortality was observed. Thus, the centre should consider appropriate measures to improve its herd reproductive performance and calves survival rate for attaining its aspired objectives.     

Plant traits related to yield of wheat in early, late, or continuous drought conditions

Bread wheats (Triticum aestivum L.) were evaluated for plant characteristics contributing to grain yield and plant adaptation under various drought patterns. The usefulness of these traits as explicit selection criteria in developing drought tolerant wheat varieties was investigated in three experiments. Cultivars from four germplasm groups, representing the four relevant major and distinct global wheat growing environments, were grown under the respective simulated early, late, continuous and no drought conditions by manipulating irrigation in north western Mexico. Additionally, 560 advanced lines from the CIMMYT breeding program were grown under late drought conditions, and 16 randomly selected advanced genotypes were studied in more detail under late and no drought conditions. In these three studies, the association between yield in drought-stressed environments and yield in non drought-stressed environments was interpreted to reflect genotypic high yield potential, mainly by way of high biomass development. However, yield potential only partly explained the superior performance under drought. For each pattern of drought stress, particular and often different plant traits were identified that further contributed specific adaptation to the distinct drought stress conditions. Knowledge of these traits will be useful for developing CIMMYT germplasm for specific drought-stressed areas. Ultimately, these studies demonstrate that both yield potential and specific adaptation traits are useful criteria in breeding for drought environments, and should be combined to achieve optimum performance and adaptation to drought stress. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of Fasciola gigantica infection on adrenal and thyroid glands of riverine buffaloes

Effect of Fasciola gigantica infection on adrenal and thyroid glands was investigated using eight male, yearling Murrah buffaloes. The animals were randomly assigned to two groups of four buffaloes each (Group-A, infected; Group-B, non-infected control). Animals of Group-A were orally infected with 1000 F. gigantica viable metacercariae, keeping other four animals of Group-B as uninfected control. In the infected buffaloes, the clinical signs began appearing from 7th week postinfection (p.i.) and eggs were detected in the faeces between day 93 and 99 (95.5+/-1.25) postinfection (p.i.). The serum cortisol level, revealed a significant (P<0.05) rise during initial stage of the infection, followed by a continuous fall from 12th week onward. Peak cortisol level on 10th week (13.30+/-2.57ngml(-1)) was associated with eosinophilia (11.0+/-0.95%). However, non-infected controls maintained almost uniform cortisol levels (3.97+/-0.15-5.88+/-0.09ngml(-1)) throughout the period of the study. The pathological changes of adrenal glands were correlated with physiological dysfunction of the glands. The levels of T(3) and T(4) were significantly (P<0.05-0.01) low from 14th week onward and were synchronous with in situ migration, growth and development of F. gigantica. Significant reduction in the thyroid hormones was further supported by histopathological evidence of lymphocytic thyroiditis confirming hypothyroidism. A decrease in Hb, PCV, total erythrocyte counts and appearance of reticulocytes in the blood of the infected buffaloes suggested regenerative anemia, which could partly be due to hypothyroidism.