The selected five plant growth-promoting rhizobacteria (PGPR) strains, WR8-3 (Pseudomonas fluorescens), WR8-6 (P. putida), WR9-9 (P. fluorescens), WR9-11 (Pseudomonas sp.), and WR9-16 (P. putida) isolated in the rhizosphere of watermelon plants were tested on their growth promotion and control effec...
The selected five plant growth-promoting rhizobacteria (PGPR) strains, WR8-3 (Pseudomonas fluorescens), WR8-6 (P. putida), WR9-9 (P. fluorescens), WR9-11 (Pseudomonas sp.), and WR9-16 (P. putida) isolated in the rhizosphere of watermelon plants were tested on their growth promotion and control effect against gummy stem rot of watermelon. Strains, WR8-3 and WR9-16 significantly increased stem length of watermelon, and there was a little increase in leaf area, fresh weight and root length when strains, WR8-3, WR9-9 and WR9-16 were treated. Generally, seed treatment was better for plant growth promotion than the soil drench, but there was no significant difference. Seed treatment and soil drench of each bacterial strain also significantly reduced the mean lesion area (MLA) by gummy stem rot, but there was no significant difference between the two treatments. At initial inoculum densities of each strain ranging from 10$^6\;to\;10^{15}$ cfu/g seed, approximately the same level of disease resistance was induced. But resistance induction was not induced at the initial inoculum density of 10$^3$ cfu/g seed. Resistance was induced by treating the strains, WR9-9, WR9-11 and WR9-16, on all of four watermelon varieties tested, and there was no significant difference in the decrease of gummy stem rot among varieties. Populations of the strains treated initially at log 9-10 cfu/g seed, followed with a rapid decrease from planting day to 1 week after planting, but the population density was maintained above log 5.0 cfu/g soil until 4 weeks after planting. Generally no or very weak in vitro antagonism was observed at the strains treated excepting WR9-11. Rifampicin-resistant bacteria which had been inoculated were not detected in the stems or leaves, which suggesting that the bacterium and the pathogens remained spatially separated during the experiment. This is the first report of rsistance induction in watermelon to gummy stem rot by PGPR strains.
The selected five plant growth-promoting rhizobacteria (PGPR) strains, WR8-3 (Pseudomonas fluorescens), WR8-6 (P. putida), WR9-9 (P. fluorescens), WR9-11 (Pseudomonas sp.), and WR9-16 (P. putida) isolated in the rhizosphere of watermelon plants were tested on their growth promotion and control effect against gummy stem rot of watermelon. Strains, WR8-3 and WR9-16 significantly increased stem length of watermelon, and there was a little increase in leaf area, fresh weight and root length when strains, WR8-3, WR9-9 and WR9-16 were treated. Generally, seed treatment was better for plant growth promotion than the soil drench, but there was no significant difference. Seed treatment and soil drench of each bacterial strain also significantly reduced the mean lesion area (MLA) by gummy stem rot, but there was no significant difference between the two treatments. At initial inoculum densities of each strain ranging from 10$^6\;to\;10^{15}$ cfu/g seed, approximately the same level of disease resistance was induced. But resistance induction was not induced at the initial inoculum density of 10$^3$ cfu/g seed. Resistance was induced by treating the strains, WR9-9, WR9-11 and WR9-16, on all of four watermelon varieties tested, and there was no significant difference in the decrease of gummy stem rot among varieties. Populations of the strains treated initially at log 9-10 cfu/g seed, followed with a rapid decrease from planting day to 1 week after planting, but the population density was maintained above log 5.0 cfu/g soil until 4 weeks after planting. Generally no or very weak in vitro antagonism was observed at the strains treated excepting WR9-11. Rifampicin-resistant bacteria which had been inoculated were not detected in the stems or leaves, which suggesting that the bacterium and the pathogens remained spatially separated during the experiment. This is the first report of rsistance induction in watermelon to gummy stem rot by PGPR strains.
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제안 방법
Colonization of the rhizosphere of plants by rifampicin-resistant PGPR strains was examined 1, 2, 3, 4 weeks after inoculation. Three pots were randomly picked on selected sampling days.
1996). In this test, effects of PGPR application methods were conducted to compare the level of plant growth and ISR resulting from PGPR application by seed treatment and soil drench. The present result shows that seed treatment increased watermelon growth a little more than the soil drench, but there was no significant difference between the two treatments.
To investigate the possibility that the observed protection was caused by a direct effect on the pathogen, the strains were tested on various media for their ability to inhibit D. bryoniae in potato dextrose agar (PDA), oat meal agar (OMA), KB, com meal agar (CMA), V-8 juice agar (V-8) plates.
To investigate the threshold population size and effect of inoculum density on the control of gummy stem rot, each PGPR strain inoculated on the seed at the concentration of log 3-15 cfu/g seed as described above.
대상 데이터
all of this experiment. And, to investigate effects of varieties on PGPR-mediated ISR, four watermelon varieties, namely Dalgona, Sambok, and Festival including Geumchon were tested.
For soil drench (SD), bacterial suspensions were poured (80 ml per pot) in the watemelon seeds planted pot. Data are means of single representative trial consists of 10 replicate plants, and stem length was investigated 3 weeks after planting. Values with the same letter are not significantly different according to DMRT (P=0.
The selected 5 PGPR strains, WR8-3 (P. fluorescens), WR8-6 (P. putida), WR9-9 (P.fluorescens), WR9-11 (Pseudomonas sp.), and WR9-16 (E putida) were used.
데이터처리
Data are means of single representative trial consists of 10 replicate plants, obtained 2, 3, and 4 weeks after planting. Values followed by common letter are not significantly different at the 5% level according to Duncan's multiple range test (DMRT). LSD at 5% level was 0.
성능/효과
, 1995). In this test, as shown in Fig. 4 increasing the rhizosphere population density of PGPR strains on seed up to approximately 106cfu/g seed, plant growth was promoted, and significant increase was observed from the inoculum density of 109cfii/g seed. At least 105 cfu/g root appears to be required for induction of systemic resistance in radish by Pseudomonas spp.
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