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 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Occurrence and Distribution of Major Seedborne Fungi Associated with Phaseolus Bean Seeds in Ethiopia) ผู้เขียน: Mohammed YESUF,  ดร.สมศิริ แสงโชติ, รองศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractA total of 245 seed samples of Phaseolus bean; 172 common beans, 51 climbing beans and 22 green beans were collected from various bean growing areas during 2003 crop season. The incidence and severity of seed infection by the major fungal diseases of bean varied between localities, bean types and cropping practices. Thirteen seed-borne fungal pathogens of different genus were identified from seed samples collected from the major bean growing regions of Ethiopia. The incidence of different seedborne fungi ranging between 0.2 to 14.5% was found to vary from location to location and growing conditions. Among them, Colletotrichum lindemuthianum, Phaeoisariopsis griseola, and Ascochyta phaseolorum were the most widespread and damaging seedborne fungal pathogens associated with Phaseolus bean seeds in Ethiopia. From the total seed samples collected, 26.2%, 19.6% and 13.6% of common bean, climbing bean and green bean respectively were infected by C. lindemuthianum, whereas infection by P. griseola was 18.6% and 15.7% on common bean and climbing beans seeds respectively. Green bean seeds were not infected by the latter two fungi. Seeds collected from south, southwest, and western part of Ethiopia showed heavy seed infection by these major fungal pathogens, whereas seeds produced in dry areas with minimum rainfall or under irrigation showed very low seed infection. Phytophthora rot of beans caused by Phytophthora sp. was also detected from green bean pods and immature seeds produced under irrigation in the central rift valley of the country. The geographic distribution of major seed-borne fungi of Phaseolus beans was mapped. |
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หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Seed Transmission and Epidemics of Colletotrichum lindemuthianum in the Major Common Bean Growing Areas of Ethiopia) ผู้เขียน:Mohammed YESUF, ดร.สมศิริ แสงโชติ, รองศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractThe seed-borne nature, mechanism of transmission and disease development of Colletotrichum lindemuthianum in the field was studied in three major common bean growing areas including Arssinegelle, Ambo and Bako in Ethiopia. The relationship between level of seed infection by Colletotrichum lindemuthianum, and its transmission to the seedlings in the field and greenhouse was studied. Multiple regression analysis showed positive and linear relationship with high coefficient of determination (R2 =0. 98, 0.91, 0.86) between seed infection and early seedling infection at Bako, Ambo and Arssinegelle respectively. During germination of the infected seeds, the pathogen was transferred from seed coat, by colonizing the cotyledons, radicle and plumule of the emerging seeds. Pre- and postemergence seedling mortalities were very common both in the field and greenhouse. Sporulation of C. lindemuthianum from acervuli was observed on the cotyledons of un-germinated seed. Moreover, sporulation of C. lindemuthianum on the growing seedling was common at Bako and Ambo where there was frequent rainfall during the crop season. Anthracnose inoculum in the field transferred to the young pods, consequently enabled the pathogen to grow through the entire pod surface, showing sunken anthracnose lesions, and infected the seed coats of the newly formed seed. Seedling infection and disease epidemic in the field varied between different bean growing locations. Seed infection by C. lindemuthianum played the major role as the main source of primary inoculum of bean anthracnose and further disease epidemic in the field. |
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