Abstract
The experiment was conducted at Annapurna farm, Tamilnadu, South India with medium straw varieties in which farmer experienced decline in yield. The overall objective of research was to identify causes of low yield and contribute to possible yield solutions in organic lowland rice. Experimental results showed that the response to nitrogen differed depending on cultivar. CP showed response to high application of nitrogen for LAI, total above ground dry matter, nitrogen content and nitrogen uptake at 85 and 120 DAT (Days After Transplanting). However, cultivar ASD did not show response to high application of nitrogen. The application of high nitrogen did not produce a strong effect on the growth parameters for both the cultivars until 60 DAT. APSIM simulated yields with a wide range of C: N ratios of soil and green manure found that the current range of C: N ratios in the farmer's field are not so high that they result in N-limited production through immobilization. The effect of the larger amount of water applied did not result in major effects on growth. Effect of AWD (Alternate wetting and Drying) was found on LAI at 85 DAT whereas farmers practice treatment did not show any effect. The difference was not so considerable for total dry matter production for both the cultivars between two irrigation regimes. APSIM simulation with double application of water did not produce any effect on growth, suggesting that the production was not water limited. The effect of zinc was different for the two cultivars. CP produced higher LAI, dry matter production and nitrogen uptake at later phase of crop when zinc had been applied. The positive effect of zinc application was seen at later phase of the crop for cultivar CP which should have shown at an early phase as per the hypothesis. Since early effects were not noticed and the results were not consistence between the cultivars, it was concluded that zinc had no major effect on crop growth. Amongst the two cultivars CP was found to be producing higher LAI, more dry matter, taking up more nitrogen and having higher yield. Varietal differences in terms of nutrient uptake capacity, resistance to anaerobic soil condition, and root structure might be accountable for the observed difference in growth parameters. The pest attack was comparatively more severe in ASD than in CP which contributed to less growth and dry matter production for ASD. Water and nitrogen limited yields simulated with APSIM were markedly higher than obtained in the experiment. One of the factors not included in APSIM and observed in the field experiment was the effect of pests and diseases on root and leaf growth. Browning of root was visually observed especially at an early stage of the crop may explain the reason for lower observed crop growth than simulated at an early stage despite ample available water and nitrogen. In this study the results did not confirm any of the hypotheses formulated. The possibilities of simulating effect of root browning on crop production specifically during the early stages of growth were not well possible. The hypothesized problem with root structure and root colour especially at initial phase of the crop needs to be investigated further. High soil organic matter content coupled with anaerobic condition leads to formation of toxic substances and root pest and diseases are some of the possible causes of root browning. Cultivar CP can be recommended if the results are consistent over the years and if not other objectives than yield is taken in to account. Further research can be conducted by using classical design mainly focusing on early growth of the crop. Nitrogen and zinc can be included and irrigation can be excluded in further research. It is recommended to use compost and consider early incorporation of fresh green manure in further experiment to observe the effect on root browning.
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Claims 20
Claim · model-written summary
High nitrogen increased CP leaf area index, dry matter, nitrogen content and uptake at 85 and 120 DAT.
- Taxon
- Rice
Oryza sativat0 - Material
- CPe0
- Treatment
- high application of nitrogene0
- Outcome
- LAI, total above ground dry matter, nitrogen content and nitrogen uptakee0
- Qualifier
- 85 and 120 DATe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CP showed response to high application of nitrogen for LAI, total above ground dry matter, nitrogen content and nitrogen uptake at 85 and 120 DAT (Days After Transplanting).”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
ASD did not respond to high nitrogen.
- Taxon
- RiceOryza sativat0
- Material
- ASDe0
- Treatment
- high application of nitrogene0
- Outcome
- responsee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cultivar ASD did not show response to high application of nitrogen.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
High nitrogen had no strong growth effect for either cultivar until 60 DAT.
- Taxon
- RiceOryza sativat0
- Treatment
- high nitrogene0
- Outcome
- growth parameterse0
- Qualifier
- until 60 DATe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The application of high nitrogen did not produce a strong effect on the growth parameters for both the cultivars until 60 DAT.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
APSIM found current soil and manure C:N ratios insufficient to cause nitrogen-limited production.
- Taxon
- RiceOryza sativat0
- Outcome
- N-limited productione0
- Qualifier
- current range of C: N ratiose0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“APSIM simulated yields with a wide range of C: N ratios of soil and green manure found that the current range of C: N ratios in the farmer's field are not so high that they result in N-limited production through immobilization.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
More applied water caused no major growth effect.
- Taxon
- RiceOryza sativat0
- Treatment
- larger amount of water appliede0
- Outcome
- growthe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effect of the larger amount of water applied did not result in major effects on growth.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Alternate wetting and drying affected LAI at 85 DAT.
- Taxon
- RiceOryza sativat0
- Treatment
- AWD (Alternate wetting and Drying)e0
- Outcome
- LAIe0
- Qualifier
- 85 DATe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Effect of AWD (Alternate wetting and Drying) was found on LAI at 85 DAT”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Farmer practice showed no LAI effect at 85 DAT.
- Taxon
- RiceOryza sativat0
- Treatment
- farmers practice treatmente0
- Outcome
- effecte0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“farmers practice treatment did not show any effect.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Total dry matter differed little between two irrigation regimes for both cultivars.
- Taxon
- RiceOryza sativat0
- Outcome
- total dry matter productione0
- Comparator
- two irrigation regimese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The difference was not so considerable for total dry matter production for both the cultivars between two irrigation regimes.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
APSIM doubling of water caused no modeled growth effect.
- Taxon
- RiceOryza sativat0
- Treatment
- double application of watere0
- Outcome
- growthe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“APSIM simulation with double application of water did not produce any effect on growth”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Zinc increased later CP LAI, dry matter and nitrogen uptake.
- Taxon
- RiceOryza sativat0
- Material
- CPe0
- Treatment
- zince0
- Outcome
- LAI, dry matter production and nitrogen uptakee0
- Direction
- highere0
- Qualifier
- at later phase of crope0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CP produced higher LAI, dry matter production and nitrogen uptake at later phase of crop when zinc had been applied.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Authors concluded zinc had no major overall crop growth effect.
- Taxon
- RiceOryza sativat0
- Treatment
- zince0
- Outcome
- crop growthe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it was concluded that zinc had no major effect on crop growth.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
CP exceeded ASD in LAI, dry matter, nitrogen uptake and yield.
- Taxon
- RiceOryza sativat0
- Material
- CPe0
- Outcome
- LAI, more dry matter, taking up more nitrogen and having higher yielde0
- Direction
- highere0
- Comparator
- two cultivarse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Amongst the two cultivars CP was found to be producing higher LAI, more dry matter, taking up more nitrogen and having higher yield.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Pest attack was more severe in ASD than CP.
Not reportedInteractor
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The pest attack was comparatively more severe in ASD than in CP which contributed to less growth and dry matter production for ASD.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Greater pest attack contributed to lower ASD growth and dry matter.
- Taxon
- RiceOryza sativat0
- Material
- ASDe0
- Outcome
- less growth and dry matter productione0
- Qualifier
- pest attacke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The pest attack was comparatively more severe in ASD than in CP which contributed to less growth and dry matter production for ASD.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
APSIM water- and nitrogen-limited yields were markedly higher than experimental yields.
- Taxon
- RiceOryza sativat0
- Outcome
- yieldse0
- Direction
- markedly highere0
- Comparator
- obtained in the experimente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water and nitrogen limited yields simulated with APSIM were markedly higher than obtained in the experiment.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Early root browning was visually observed.
- Taxon
- RiceOryza sativat0
- Organ / stage
- roote0
- Outcome
- Browning of roote0
- Qualifier
- at an early stage of the crope0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Browning of root was visually observed especially at an early stage of the crop”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Early root browning may explain lower observed than simulated early growth.
- Taxon
- RiceOryza sativat0
- Organ / stage
- roote0
- Outcome
- lower observed crop growth than simulatede0
- Qualifier
- Browning of roote0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Browning of root was visually observed especially at an early stage of the crop may explain the reason for lower observed crop growth than simulated at an early stage despite ample available water and nitrogen.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Authors recommend CP for yield if results persist across years.
- Taxon
- RiceOryza sativat0
- Material
- CPe0
- Outcome
- CP can be recommendede0
- Qualifier
- if the results are consistent over the yearse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cultivar CP can be recommended if the results are consistent over the years and if not other objectives than yield is taken in to account.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Authors recommend classical experiments focused on early crop growth, including nitrogen and zinc but excluding irrigation.
- Taxon
- RiceOryza sativat0
- Outcome
- classical design mainly focusing on early growth of the crope0
- Qualifier
- Nitrogen and zinc can be included and irrigation can be excludede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Further research can be conducted by using classical design mainly focusing on early growth of the crop. Nitrogen and zinc can be included and irrigation can be excluded in further research.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
Claim · model-written summary
Authors recommend compost and early fresh green manure incorporation to study root browning.
- Taxon
- RiceOryza sativat0
- Outcome
- use compost and consider early incorporation of fresh green manuree0
- Qualifier
- observe the effect on root browninge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It is recommended to use compost and consider early incorporation of fresh green manure in further experiment to observe the effect on root browning.”
t0“Yield Constraint Analysis of Lowland Organic Rice at Annapurna Farm, South India: Field Measurements and Modelling”
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