Citation
Lee, Kam Loong
(2003)
Combined Effect of Calcium Nitrate and Fluorescent Pseudomonads on Bacterial Wilt Caused by Ralstonia Solanacearum.
Masters thesis, Universiti Putra Malaysia.
Abstract
A study on the combined effect of calcium nitrate and fluorescent
Pseudomonads on bacterial wilt caused by Ralstonia solanacearum on
tomato was carried out in the greenhouse and field. Greenhouse studies
showed that application of calcium nitrate solution at 0.1 % and 0.5% on
tomato seedlings prior to transplanting gave significant increase (p<0.01)
on the fresh and dry weight of the treated seedlings compared to the 1%
treatment and the non-treated control. Application of 0.5% calcium nitrate
solution prior to transplanting, complemented with application of granular
calcium nitrate after transplanting gave significant reduction (p<0.01) on
bacterial wilt incidence on tomato seedlings planted in soil artificially
infested with R. solanacearum at approximately 106 cfu/g oven-dry soil.
Four strains of antagonistic Pseudomonads, that inhibited the growth of
R. solanacearum on dual-culture plates, were tested individually in biopriming
(approximately 1 X 108 cfu/ml in 1.5% methylcellulose) on their effects towards seed germination and biomass of the treated tomato
seedlings. Pseudomonas putida strains KTS26 and AC1 individually gave
significant (p<0.01) increase on germination (%) compared to when
seeds were coated with methylcellulose only. Fresh weight of 30-days-old
seedlings was significantly increased (p<0.01) by bio-priming with
combination of KTS26 and AC1 , and with KTS26 alone. However, dry
weight of seedlings was not affected by the treatments.
G reenhouse studies were conducted to evaluate the combined effects of
seed bio-priming with Pseudomonas pufida strains KTS26 and AC1 ,
either individually or in combination; application of calcium nitrate, at
regular intervals, prior to and after transplanting; and application of
Stonier's medium (half-strength) in controlling bacterial wilt on MT11 up to
6 weeks after transplanting. All combination of treatments significantly
(p0.01) reduced the disease, compared to the non-treated control.
However, no significant difference was observed between the treatments.
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