Seed health status of rice and onion under the quality declared seed system: the case of Morogoro, Iringa and Dodoma Regions
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Date
2006
Journal Title
Journal ISSN
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Publisher
Sokoine University of Agriculture
Abstract
A study was conducted to determine the seed health status of rice and onion
produced under the quality declared seed (QDS) system in Tanzania. Using a
purposeful sampling technique, a total of 34 QDS farmers from Morogoro, Iringa
and Dodoma regions were interviewed using a structured questionnaire. Seventeen
QDS samples each of rice and onion were collected from the interviewed farmers
from respective regions. The Blotter method was used to detect the fungal pathogens.
Identification of the detected fungi was done based on growth habit and
morphological characters of fruiting bodies and spores/conidia. The cassette holder
and direct plating methods were used to detect and isolate bacterial pathogens. The
isolated bacteria were characterized based on physiological tests, Biolog and
pathogenicity tests. All QDS onion and rice seed samples tested were infected by
fungal pathogens. Aspergillus niger and A. flavus were common detected fungal
pathogens in all onion seed samples. In rice seed samples, Phoma sp., Bipolar is
oryzae and Fusarium pallidoroseum were common detected fungal pathogens.
Bacterial pathogens were identified in 41.2 % and 52.9 % of onion and rice seed
samples, respectively. Pantoea agglomerans, P. dispersa, Ralstonia pickettii and
Enterobacter cloacae were identified as new pathogens on onion in Tanzania while
P. agglomerans, Flavimonas oryzihabitans, Pseudomonas resinovorans, P. maculicola and E. aerogenes emerged as the new bacterial pathogens of rice. Insect
pests were found to be of major importance in producing good quality and healthy
seed under the QDS production system. The results stress the importance of checking
the seed health status of QDS in order to ensure the production and use of healthy seed. Future studies should be conducted on the importance of such detected
organisms under field and onion storage conditions. Insect pests should also be taken
up as a problem to be addressed by the QDS system.
Description
Dissertation
Keywords
Dodoma Region, Seed health status, Seed system, Quality declared seed (QDS), Isolate bacterial pathogens