Browsing by Author "Geoffrey, Tusiime"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Evaluation of Rice Germplasm Reveals Sources of Bacterial Leaf Streak Disease Resistance in Uganda
    (Journal of Food Security, 2018) Michael, Kanaabi; Geoffrey, Tusiime; Phinehas, Tukamuhabwa; Jordan, Andaku; David, Ocan; Jimmy, Lamo
    In 2014, researchers in Uganda spotted signs typical bacterial leaf streak disease (Xanthomonas oryzae pv. oryzicola) in rice fields in Eastern Uganda. The disease was later confirmed to be bacterial leaf streak. In order to effectively plan for measures to manage this potentially devastating disease, it was imperative to score rice germplasm in Uganda for reaction to Xoc. Eighty four genotypes from the National Rice Improvement program were evaluated for their reaction to BLS using two Xoc isolates collected from Namulonge and Iganga. These were inoculated by the infiltration method using a needless syringe 30 days after planting. Data were collected on the streak length induced by BLS on the leaves 15 days after inoculation. The mean streak length per genotype was interpreted as; Resistant (R), 030mm. Genotypes showed signficant variability (P < 0.001) in their reaction to BLS. The Xoc isolates reacted signficantly differently (P=0.011) on the rice genotypes. For the Iganga isolate, 6 genotypes were resistant while 17 were moderately resistant. For the Namulonge isolate, 3 genotypes were resistant while 7 were moderately resistant. Three genotypes were resistant to both isolates. The observations ranged from highly resistant in Nerica1 to highly susceptible in Du 363. The resistant genotypes identified could be used as sources of genes for introgression into susceptible but agronomically desirable genotypes.
  • 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.