Abstract
ABSTRACT Seedling disease, caused primarily by several species of Pythium, is one of the major constraints to water-seeded rice production in Louisiana. The disease, also known as water-mold disease, seed rot, and seedling damping-off, causes stand reductions and growth abnormalities. In severe cases, fields must be replanted, which may result in delayed harvests and reduced yields. To develop more effective disease management tactics including biological control, this study was conducted primarily to determine sites of infection in seeds and seedlings; effect of plant age on susceptibility to P. arrhenomanes, P. myriotylum, and P. dissotocum; and minimum exposure times required for infection and seedling death. In addition, the effect of water depth on seedling disease was investigated. Infection rates of seed embryos were significantly higher than those of endosperms for all three Pythium spp. The development of roots from dry-seeded seedlings was significantly reduced by P. arrhenomanes and P. myriotylum at 5 days after planting compared with that of roots from noninoculated controls. Susceptibility of rice to all three species was sharply reduced within 2 to 6 days after planting, and seedlings were completely resistant at 8 days after planting. There was a steep reduction in emergence through the flood water, relative to the noninoculated control, following 2 to 3 days of exposure to inoculum of P. arrhenomanes and P. myriotylum. In contrast, P. dissotocum was much less virulent and required longer exposure times to cause irreversible seedling damage. Disease incidence was higher when seeds were planted into deeper water, implying that seedlings become resistant after they emerge through the flood water. These results suggest that disease control tactics including flood water management need to be employed for a very short period of time after planting. Also, given that the embryo is the primary site of infection and it is susceptible for only a few days, the disease should be amenable to biological control.
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Claims 10
Claim · model-written summary
Seed embryos had higher infection rates than endosperms for all three Pythium species.
- Taxon
- Rice
Oryza sativat0 - Organ / stage
- seed embryose0
- Outcome
- Infection ratese0
- Direction
- highere0
- Comparator
- endospermse0
.jpg?width=60){kind=small}
PythiumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Infection rates of seed embryos were significantly higher than those of endosperms for all three Pythium spp.”
t0“Rice Seedlings”
Claim · model-written summary
P. arrhenomanes reduced root development of five-day dry-seeded rice relative to noninoculated controls.
- Taxon
- RiceOryza sativat0
- Treatment
- P. arrhenomanese0
- Interactor
- P. arrhenomanesPythium arrhenomanese0pathogen
- Outcome
- development of rootse0
- Direction
- reducede0
- Qualifier
- 5 days after plantinge0
- Comparator
- noninoculated controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The development of roots from dry-seeded seedlings was significantly reduced by P. arrhenomanes and P. myriotylum at 5 days after planting compared with that of roots from noninoculated controls”
t0“Rice Seedlings”
Claim · model-written summary
P. myriotylum reduced root development of five-day dry-seeded rice relative to noninoculated controls.
- Taxon
- RiceOryza sativat0
- Treatment
- P. myriotylume0
- Interactor
- P. myriotylumPythium myriotylume0pathogen
- Outcome
- development of rootse0
- Direction
- reducede0
- Qualifier
- 5 days after plantinge0
- Comparator
- noninoculated controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The development of roots from dry-seeded seedlings was significantly reduced by P. arrhenomanes and P. myriotylum at 5 days after planting compared with that of roots from noninoculated controls”
t0“Rice Seedlings”
Claim · model-written summary
Rice susceptibility to three Pythium species declined sharply two to six days after planting and seedlings were resistant by day eight.
- Taxon
- riceOryza sativae0
- Outcome
- Susceptibilitye0
- Direction
- sharply reducede0
- Qualifier
- 2 to 6 days after plantinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Susceptibility of rice to all three species was sharply reduced within 2 to 6 days after planting, and seedlings were completely resistant at 8 days after planting”
Claim · model-written summary
Exposure to P. arrhenomanes inoculum for two to three days sharply reduced rice emergence through floodwater.
- Taxon
- RiceOryza sativat0
- Treatment
- exposure to inoculum of P. arrhenomanese0
- Interactor
- P. arrhenomanesPythium arrhenomanese0pathogen
- Outcome
- emergence through the flood watere0
- Direction
- steep reductione0
- Qualifier
- 2 to 3 dayse0
- Comparator
- noninoculated controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a steep reduction in emergence through the flood water, relative to the noninoculated control, following 2 to 3 days of exposure to inoculum of P. arrhenomanes and P. myriotylum”
t0“Rice Seedlings”
Claim · model-written summary
Exposure to P. myriotylum inoculum for two to three days sharply reduced rice emergence through floodwater.
- Taxon
- RiceOryza sativat0
- Treatment
- exposure to inoculum of P. arrhenomanes and P. myriotylume0
- Interactor
- P. myriotylumPythium myriotylume0pathogen
- Outcome
- emergence through the flood watere0
- Direction
- steep reductione0
- Qualifier
- 2 to 3 dayse0
- Comparator
- noninoculated controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a steep reduction in emergence through the flood water, relative to the noninoculated control, following 2 to 3 days of exposure to inoculum of P. arrhenomanes and P. myriotylum”
t0“Rice Seedlings”
Claim · model-written summary
P. dissotocum was less virulent and required longer exposure for irreversible seedling damage.
- Taxon
- RiceOryza sativat0
- Interactor
- P. dissotocumPythium dissotocume0pathogen
- Outcome
- virulente0
- Direction
- much lesse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“P. dissotocum was much less virulent and required longer exposure times to cause irreversible seedling damage”
t0“Rice Seedlings”
Claim · model-written summary
Deeper planting water increased rice seedling disease incidence.
- Taxon
- RiceOryza sativat0
- Treatment
- deeper watere0
- Outcome
- Disease incidencee0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Disease incidence was higher when seeds were planted into deeper water”
t0“Rice Seedlings”
Claim · model-written summary
The authors recommend early floodwater management to control rice seedling disease.
- Taxon
- RiceOryza sativat0
- Outcome
- flood water managemente0
- Qualifier
- a very short period of time after plantinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“disease control tactics including flood water management need to be employed for a very short period of time after planting”
t0“Rice Seedlings”
Claim · model-written summary
The authors considered biological control feasible because embryos are the main infection site and susceptible for only a few days.
- Taxon
- RiceOryza sativat0
- Organ / stage
- embryoe0
- Outcome
- biological controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“given that the embryo is the primary site of infection and it is susceptible for only a few days, the disease should be amenable to biological control”
t0“Rice Seedlings”
The same questions in other papers
Pythium arrhenomanes · growth · Oryza sativa (rice)Results agree
2 papers in the same direction as this paper
- negative
- negative
inoculation · growth · Oryza sativa (rice)Positive and negative results
36 papers in the same direction as this paper · 362 in the opposite direction
- positive
- positive
- positive
395 papers more in this group
See all 399 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.