Screening farmers’ saved rice seed for discolouration and incidence of seed-borne pathogens
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Date
2009
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Sokoine University of Agriculture
Abstract
A study was conducted to screen for seed-borne pathogens causing discolouration in
farmers’ saved rice seeds produced in Shinyanga, Mbeya and Morogoro regions in
Tanzania.
A total of 37 seed samples were tested for the presence of seed-borne
pathogens. The blotter method was used to detect fungal pathogens which were identified
based on growth habit and morphological characteristics of the fruiting bodies and
spores/conidia. The slide cassette holder method was used to detect bacterial pathogens.
The isolated bacteria were characterized based on physiological and biochemical tests,
hypersensitive reaction and pathogenicity tests. The data were analyzed using MSTAT-C
Computer package and mean separation rest using Duncan’s Multiple Range Test at
P < 0.05. The identified seed-borne fungal pathogens associated with seed discolouration
were Fusarium moniliforme, Phoma sp., Bipolaris oryzae and Altemaria padwickii. All
farmers’ saved rice seed samples tested were infected. The highest seed infection was
caused by Fusarium moniliforme (16.75%), (26.0%), (13.5%), Bipolaris oryzae (2.0%),
(0.5%), (17.25%), Phoma sp. (5.0%), (2.25%), (2.25%) for samples from Shinyanga,
Mbeya and Morogoro, respectively. The lowest seed infection was caused by Alternaria
padwickii (0.25%), (0.75%) for samples from Shinyanga and Mbeya, respectively. Seed-
borne bacterial pathogens causing grain discolouration were identified. The highest seed
infection with Acidovorax avenae subsp. avenae was from Shinyanga region,
Pseudomonas syringae subsp. syringae from Morogoro region and Psudomonas
fuscovaginae infection from samples collected in Morogoro and Mbeya regions. Rice seed
from Shinyanga region had high seed infection followed by Morogoro. The results stress
the need to encourage farmers to use certified seed which are clean and healthy for
planting rather than using their owned saved seeds.
Description
Dissertation
Keywords
Seed-borne, Pathogens, Rice seeds, Shinyanga, Mbeya, Morogoro, Tanzania Regions