Agriculture Reference
In-Depth Information
K20Bacillus megaterium N2S6 (Nishijima et al. 2005)
were added into unused pumice at a
density of 5 x 10
7
cfu g
-1
pumice, to which R. solanacearum YU1Rif43 were inoculated at a
density of 5 x 10
4
cfu g
-1
pumice and added with different carbon sources at a rate of 1 mg g
-1
.
One hundred gram of the unused pumice containing biocontrol agent-pathogen-substrate
mixture was put into a vinyl pot with 9 cm diameter and six of two days old tomato seeds
(Lycopersicon esculentum Mill. cv. Momotaro) were transplanted into a pot. Pots were
prepared in triplicates per treatment and grown in a Biotron (LPH200, Nippon Medical and
Chemical Instruments Co., Ltd., Osaka, Japan; day:night=12h:12h, 285 µmol m
-2
s
-1
(photon
flux), at 30C). Substrates were also added after 2 weeks of seeding.
Cultivation of Tomato in A Greenhouse
Twelve two days old tomato seeds (Lycopersicon esculentum Mill. cv. House Momotaro)
were transplant into a 0.05 m
2
pot containing 3.5 kg pumice (equivalent to 7L volume)
inoculated with biocontrol agents and the pathogen at densities of 5 x 10
7
and 5 x 10
4
cfu g
-1
pumice, respectively. Seeding was done in September 14, 2005 and September 24, 2006. The
pots planted with tomato were put on a heater mat (Takii Co., Ltd., Kyoto, Japan) and grown
in a greenhouse. Twelve seedlings were thinned to 3 after one month, then to one after two
months and cultivated until the end of February each year. Substrates were added into each
pot at a rate of 1 mg g
-1
of pumice in 2005 and 0.25 mg g
-1
of pumice in 2006 every two
weeks from just after seeding. Watering was done using Otsuka liquid fertilizer A formula
one to two times a day to adjust its moisture content to pF 2.0. Fifty % of concentration of the
liquid fertilizer was used until the first flowering and then 75% of that until initial
enlargement of fruits.
S
TATISTICS
Statistical analysis (mainly ANOVA) was done using the software Excel statistics 2002
(Social Survey Research Information, Tokyo, Japan).
R
ESULTS AND
D
ISCUSSION
Disease Suppressiveness of Used Pumice
When unused (new) and used pumice in which crops were continuously grown for 13
years were inoculated with the same amount of R. solanacearum and then tomato was grown,
almost all tomato plants died in the unused pumice, but most of them survived in the used
pumice (Figure 1). This tendency was observed consistently in six times repeated
experiments. The used pumice was also suppressive to damping-off caused by Pythium
aphanidermatum and Fusairum wilt caused by Fusarium oxysporum f. sp. lycopersici (Figure
1). It was considered that virgin pumice is susceptible to different belowground plant
