Abstract
Seedborne infection of rice by Pyricularia oryzae and its transmission to seedlings were studied quantitatively with naturally infected seeds of three rice cultivars collected from three locations in Nepal. A linear relationship on a logistic scale was found between panicle symptoms and seed infection, i.e., the more symptoms the higher seed infection. However, healthy-looking panicles and branches of panicles could also yield infected seeds. Postharvest measures such as winnowing and sun-drying significantly reduced seed infection by P. oryzae and filled grains had a lower degree of infection than unfilled grains. Sporulation of P. oryzae was most often confined to the embryonal end of germinating seeds. In contrast, most of the nongerminating seeds had sporulation all over the seed surface. Transmission of P. oryzae from seeds to seedlings, studied under various seeding conditions, showed that the transmission rate was always low. Thus, a seed sample with 21% seed infection resulted in less than 4% seedlings with blast lesions. Seed transmission was found for light covering of the seeds with soil or for moist seeding without covering. Transmission was rarely found when seeds were completely covered, and never in seedlings raised under water seeding conditions. Lower infection frequency was observed in seedlings raised in unsterilized soil than in seedlings raised in sterilized soil. Also, percent recovery of P. oryzae from infected seeds was higher in sterilized soil than in unsterilized soil and declined with time. Seedlings grown under low temperature (15 to 20°C) conditions did not develop blast lesions but when the same plants were transferred to high temperature (25 to 30°C) conditions, blast lesions were detected. This confirmed the latent infection in seedlings by P. oryzae grown under low temperature conditions.
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Claims 17
Claim · model-written summary
Panicle symptoms increased with seed infection.
- Taxon
- rice
Oryza sativat0 - Organ / stage
- paniclee0
- Outcome
- seed infectione0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A linear relationship on a logistic scale was found between panicle symptoms and seed infection, i.e., the more symptoms the higher seed infection.”
t0“Rice”
Claim · model-written summary
Healthy-looking panicles and branches could yield infected seeds.
- Taxon
- RiceOryza sativat0
- Organ / stage
- panicles and branches of paniclese0
- Outcome
- infected seedse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“healthy-looking panicles and branches of panicles could also yield infected seeds.”
t0“Rice”
Claim · model-written summary
Winnowing significantly reduced seed infection.
- Taxon
- RiceOryza sativat0
- Treatment
- winnowinge0
- Interactor
- P. oryzae
Pyricularia oryzaee0pathogen - Outcome
- seed infection by P. oryzaee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Postharvest measures such as winnowing and sun-drying significantly reduced seed infection by P. oryzae”
t0“Rice”
Claim · model-written summary
Sun-drying significantly reduced seed infection.
- Taxon
- RiceOryza sativat0
- Treatment
- sun-dryinge0
- Interactor
- P. oryzaePyricularia oryzaee0pathogen
- Outcome
- seed infection by P. oryzaee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Postharvest measures such as winnowing and sun-drying significantly reduced seed infection by P. oryzae”
t0“Rice”
Claim · model-written summary
Filled grains had lower infection than unfilled grains.
- Taxon
- RiceOryza sativat0
- Material
- filled grainse0
- Outcome
- degree of infectione0
- Direction
- lowere0
- Comparator
- unfilled grainse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“filled grains had a lower degree of infection than unfilled grains.”
t0“Rice”
Claim · model-written summary
P. oryzae sporulation on germinating seeds was usually at the embryonal end.
- Taxon
- RiceOryza sativat0
- Organ / stage
- germinating seedse0
- Interactor
- P. oryzaePyricularia oryzaee0pathogen
- Outcome
- Sporulation of P. oryzaee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sporulation of P. oryzae was most often confined to the embryonal end of germinating seeds.”
t0“Rice”
Claim · model-written summary
P. oryzae sporulation on most nongerminating seeds covered the seed surface.
- Taxon
- RiceOryza sativat0
- Organ / stage
- nongerminating seedse0
- Outcome
- sporulation all over the seed surfacee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“most of the nongerminating seeds had sporulation all over the seed surface.”
t0“Rice”
Claim · model-written summary
Seed-to-seedling transmission was consistently low.
- Taxon
- RiceOryza sativat0
- Outcome
- transmission ratee0
- Value
- less than 4%e0
- Qualifier
- 21% seed infectione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the transmission rate was always low. Thus, a seed sample with 21% seed infection resulted in less than 4% seedlings with blast lesions.”
t0“Rice”
Claim · model-written summary
Light soil covering allowed seed transmission.
- Taxon
- RiceOryza sativat0
- Treatment
- light covering of the seeds with soile0
- Outcome
- Seed transmission was founde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seed transmission was found for light covering of the seeds with soil or for moist seeding without covering.”
t0“Rice”
Claim · model-written summary
Moist seeding without covering allowed seed transmission.
- Taxon
- RiceOryza sativat0
- Treatment
- moist seeding without coveringe0
- Outcome
- Seed transmission was founde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seed transmission was found for light covering of the seeds with soil or for moist seeding without covering.”
t0“Rice”
Claim · model-written summary
Complete covering rarely yielded transmission.
- Taxon
- RiceOryza sativat0
- Treatment
- seeds were completely coverede0
- Outcome
- Transmission was rarely founde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transmission was rarely found when seeds were completely covered”
t0“Rice”
Claim · model-written summary
Water seeding yielded no observed transmission.
- Taxon
- RiceOryza sativat0
- Treatment
- water seeding conditionse0
- Outcome
- never in seedlings raised under water seeding conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“never in seedlings raised under water seeding conditions.”
t0“Rice”
Claim · model-written summary
Seedling infection frequency was lower in unsterilized soil.
- Taxon
- RiceOryza sativat0
- Outcome
- infection frequencye0
- Direction
- Lowere0
- Comparator
- sterilized soile0
- Setting
- unsterilized soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lower infection frequency was observed in seedlings raised in unsterilized soil than in seedlings raised in sterilized soil.”
t0“Rice”
Claim · model-written summary
P. oryzae recovery was higher in sterilized soil.
- Taxon
- RiceOryza sativat0
- Interactor
- P. oryzaePyricularia oryzaee0pathogen
- Outcome
- percent recovery of P. oryzae from infected seedse0
- Direction
- highere0
- Comparator
- unsterilized soile0
- Setting
- sterilized soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“percent recovery of P. oryzae from infected seeds was higher in sterilized soil than in unsterilized soil and declined with time.”
t0“Rice”
Claim · model-written summary
P. oryzae recovery from infected seeds declined over time.
- Taxon
- RiceOryza sativat0
- Interactor
- P. oryzaePyricularia oryzaee0pathogen
- Outcome
- percent recovery of P. oryzae from infected seedse0
- Direction
- declinede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“percent recovery of P. oryzae from infected seeds was higher in sterilized soil than in unsterilized soil and declined with time.”
t0“Rice”
Claim · model-written summary
Seedlings at 15 to 20°C did not develop blast lesions.
- Taxon
- RiceOryza sativat0
- Outcome
- did not develop blast lesionse0
- Value
- 15 to 20°Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seedlings grown under low temperature (15 to 20°C) conditions did not develop blast lesions”
t0“Rice”
Claim · model-written summary
Blast lesions appeared after seedlings moved to 25 to 30°C.
- Taxon
- RiceOryza sativat0
- Treatment
- high temperature (25 to 30°C) conditionse0
- Outcome
- blast lesions were detectede0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when the same plants were transferred to high temperature (25 to 30°C) conditions, blast lesions were detected.”
t0“Rice”
The same questions in other papers
heat · disease · Oryza sativa (rice)Positive and negative results
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