Abstract
The effect of nitrogenous-fertilization on the population dynamics and natural control of rice leaffolders was studied in an irrigated rice area in the Philippines. Nitrogen was applied at three levels (0, 75 and 150 kg N ha-1), and its impact on crop growth and yield, arthropod abundance, and rates of leaffolder parasitism and survival was assessed with weekly samples. Rice plants were taller and had a higher leaf nitrogen content with increasing levels of nitrogenous fertilization, but grain yield was highest at the medium nitrogen level. Herbivores, predators, and parasitoids increased in abundance with nitrogenous-fertilization level. The average density of rice leaffolder larvae at the highest nitrogen level was eight times the density at zero nitrogen level, and the peak percentage injured leaves increased from 5 to 35&Eth;The strong increase in larval density was due to the positive effect of nitrogenous-fertilization on egg recruitment and survival of medium-sized larvae. The percentage parasitism of eggs and larvae was not affected by nitrogenous-fertilization. The increase in survival of medium-sized larvae with nitrogen levels was associated with lower predator to leaffolder ratios. The strong effect of nitrogenous-fertilization in the present small-scale experiment was attributed mainly to allowing the moths an oviposition choice between plots with different application levels of nitrogen. Therefore it is hypothesized that the effect of increasing nitrogenous-fertilization level on leaffolder larval densities will be less pronounced when implemented over a large area.
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Claims 9
Claim · model-written summary
Leaf nitrogen content of rice increased with increasing nitrogenous fertilization.
- Taxon
- rice
Oryza sativat0 - Treatment
- nitrogenous fertilizatione1
- Outcome
- leaf nitrogen contente1
- Direction
- highere1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice leaffolders”
e1“had a higher leaf nitrogen content with increasing levels of nitrogenous fertilization”
Claim · model-written summary
Rice plants became taller with increasing nitrogenous fertilization.
- Taxon
- RiceOryza sativae2
- Treatment
- nitrogenous fertilizatione2
- Outcome
- tallere2
- Direction
- tallere2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice leaffolders”
e2“Rice plants were taller and had a higher leaf nitrogen content with increasing levels of nitrogenous fertilization”
Claim · model-written summary
Herbivores, predators and parasitoids increased in abundance with the nitrogenous fertilization level.
- Taxon
- riceOryza sativat0
- Treatment
- nitrogenous-fertilization levele4
- Interactor
- Herbivorese4herbivore
- Second interactor
- predatorse4biocontrol_agent
- Outcome
- abundancee4
- Direction
- increasede4
- Qualifier
- and parasitoidse4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice leaffolders”
e4“Herbivores, predators, and parasitoids increased in abundance with nitrogenous-fertilization level”
Claim · model-written summary
Grain yield was highest at the medium nitrogen level.
- Taxon
- riceOryza sativat0
- Treatment
- medium nitrogen levele3
- Outcome
- grain yielde3
- Direction
- higheste3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice leaffolders”
e3“but grain yield was highest at the medium nitrogen level”
Claim · model-written summary
Density of rice leaffolder larvae at the highest nitrogen level was eight times that at zero nitrogen.
- Taxon
- riceOryza sativat0
- Treatment
- highest nitrogen levele5
- Interactor
- rice leaffolder
Cnaphalocrocis medinalise5pest - Outcome
- density of rice leaffolder larvaee5
- Direction
- increaseinferrede5
- Value
- eight timese5
- Comparator
- zero nitrogen levele5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice leaffolders”
e5“The average density of rice leaffolder larvae at the highest nitrogen level was eight times the density at zero nitrogen level”
Claim · model-written summary
Peak percentage of injured leaves increased from 5 to 35 with nitrogenous fertilization.
- Taxon
- riceOryza sativat0
- Treatment
- nitrogenous-fertilizatione6
- Interactor
- leaffolderst0pest
- Outcome
- peak percentage injured leavese7
- Direction
- increasede7
- Value
- 5 to 35e7
- Setting
- Philippinese6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice leaffolders”
e6“The effect of nitrogenous-fertilization on the population dynamics and natural control of rice leaffolders was studied in an irrigated rice area in the Philippines”
e7“the peak percentage injured leaves increased from 5 to 35”
Claim · model-written summary
The increase in leaffolder larval density under nitrogen was explained by the effect of nitrogenous fertilization on egg recruitment and survival of medium-sized larvae.
- Taxon
- riceOryza sativat0
- Treatment
- nitrogenous-fertilizatione2
- Outcome
- increase in larval densitye2
- Qualifier
- egg recruitment and survival of medium-sized larvaee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice leaffolders”
e2“The strong increase in larval density was due to the positive effect of nitrogenous-fertilization on egg recruitment and survival of medium-sized larvae”
Claim · model-written summary
Percentage parasitism of leaffolder eggs and larvae was not affected by nitrogenous fertilization.
- Taxon
- riceOryza sativat0
- Treatment
- nitrogenous-fertilizatione3
- Outcome
- percentage parasitism of eggs and larvaee3
- Direction
- not affectede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice leaffolders”
e3“The percentage parasitism of eggs and larvae was not affected by nitrogenous-fertilization”
Claim · model-written summary
Increased survival of medium-sized leaffolder larvae with nitrogen levels was associated with lower predator to leaffolder ratios.
- Taxon
- riceOryza sativat0
- Treatment
- nitrogen levelse4
- Interactor
- leaffoldere4pest
- Second interactor
- predatore4biocontrol_agent
- Outcome
- survival of medium-sized larvaee4
- Direction
- increasee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice leaffolders”
e4“The increase in survival of medium-sized larvae with nitrogen levels was associated with lower predator to leaffolder ratios”
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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.