Browsing by Author "Patrick, Rubaihayo"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Incidence and Distribution of Downy Mildew Disease (Peronosclerospora Sorghi) of Sorghum in Uganda
    (International Journal of Advanced Research (IJAR), 2018) Frank, Kumi; Symphorien, Agbahoungba; Arfang, Badji; Thomas, Odong; Richard, Edema; Mildred, Ochwo- Ssemakula; Dianah, Nakubulwa; Geoffrey, Tusiime; Moses, Biruma; Patrick, Rubaihayo
    Sorghum (Sorghum bicolor) ranks as the third most important staple cereal food crop in Uganda after maize and millet. The crop is hampered by several biotic stresses of which Sorghum Downy Mildew disease is one of the most devastating diseases. The disease is caused by a soil-borne fungus Peronosclerospora sorghi but it is also air-borne through conidia. Incidence and severity of downy mildew were conducted between March-June, 2016 and September-December 2016 growing seasons in 13 sorghum-growing districts across ten agroecological zones. Data collected were subjected to analyses of variance, correlation and linear regression. Significant (P < 0.001) differences were recorded for disease incidence and severity across the different agro ecologies. The mean downy mildew disease incidence varied significantly (P< 0.001) from 49.4 % for Pader to 78.9 % for Namutumba. Disease severity varied significantly (P <0.001) from 2.3 for Pader to 3.5 for Pallisa. Chi-square test for independent association between cropping season and downy mildew disease incidence showed a high significant test statistic values (χ2 = 140.89, d.f = 3, and P < 0.001). A significant (P<0.001) positive correlation was observed between disease incidence and severity (r = 0.498) while a significant negative correlation was observed between disease incidence and rainfall (r = -0.675) due largely to temperature and relative humidity. Multiple linear regression analysis revealed that temperature, relative humidity, rainfall and altitude explained 49 % of the total variation associated to disease incidence. Variations in the incidence and severity of downy mildew disease prompt the need to screen for resistant/tolerant sorghum varieties.
  • Thumbnail Image
    Item
    Phenotypic and genotypic screening for rust resistance in common bean germplasm in Uganda
    (Euphytica, 2017) Odogwu, Blessing A.; Nkalubo, Stanley T.; Mukankusi, Clare; Odong, Thomas; Awale, Halima E.; Patrick, Rubaihayo; Kelly, James D.
    Rust caused by Uromyces appendiculatus (Pers., Pers.) Unger is one of the major foliar diseases of common bean (Phaseolus vulgaris) in Uganda. The use of host resistance remains the best option in managing this disease. The objective of this study was to identify sources of broad-spectrum rust resistance in common bean germplasm including landraces, commercial and introduced genotypes using a combination of phenotypic and genotypic screening with simple sequence repeats (SSRs) markers located on chromosome Pv04. A total of 138 cultivars were field screened from 2014 and 2015 using alpha lattice design. The variance and correlation of disease incidence, area under the disease progression curve (AUDPC) and total grain yield were computed using GenStat. The polymorphism information content of the cultivars was determined, and the association of the markers and the disease resistance traits were analyzed using PowerMarker and TASSEL respectively. Resistance of each cultivar was compared to the presence and absence of amplified markers. There were highly significant differences (P < 0.001) among the cultivars for disease incidence, AUDPC and total grain yield and a strong correlation (P < 0.001) between disease incidence and AUDPC in both years. The SSR markers, BARC_PV_SSR04725, bean_ssr_0778 and bean_ssr_2892 were observed to be associated (P ≤0.05) with rust resistance. The two screening methods identified cultivars which included local cultivars, Nabufumbo, Kapchorwa white, and NABE as new sources of rust resistance. This study identified sources of rust resistance that would be useful in the bean breeding programmes in Uganda.