Abstract
Wet direct-seeded rice (Oryza sativa L.) (DSR) is an attractive alternative to transplanted rice, as it saves the drudgery of raising seedlings and transplanting, reducing labor and cost of cultivation. As DSR stays in the field for a longer duration than transplanted rice and water management differs considerably, particularly during early growth stages, need-based fertilizer N management in DSR using chlorophyll meter (SPAD meter) and leaf color chart (LCC) was investigated vis-à-vis fixed-time N application schedules. Applying fertilizer N following sufficiency index approach that ensures maintaining intensity of the color of the uppermost fully opened rice leaves at 90% or more of the intensity of the color of the leaves in the over-fertilizer reference plot, resulted in application of only 70 kg N ha−1. It resulted in grain yield of rice equivalent to that produced by applying 80 or 120 kg N ha_1 in four equal split doses. Since rice farmers may not be able to follow the sufficiency-index approach, two experiments were conducted to find the critical color shade on the LCC to guide need-based fertilizer N application to DSR. Application of 30 kg N ha−1 whenever intensity of the color of the uppermost fully opened leaf of the rice plant was less than LCC shade 3 (LCC3) resulted in higher yields than application of 80 and 120 kg N ha−1 in four equal split doses at fixed times. As higher fertilizer N-use efficiency was recorded with need-based N management using LCC3 rather than LCC 4 as critical color shade, this study suggested that to obtain high yields and N-use efficiency, fertilizer N application should be guided by LCC3.
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Claims 5
Claim · model-written summary
The sufficiency-index approach required only 70 kg N ha−1.
- Taxon
- rice
Oryza sativae0 - Treatment
- sufficiency index approache0
- Outcome
- applicatione0
- Direction
- onlye0
- Value
- 70 kg N ha−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Applying fertilizer N following sufficiency index approach that ensures maintaining intensity of the color of the uppermost fully opened rice leaves at 90% or more of the intensity of the color of the leaves in the over-fertilizer reference plot, resulted in application of only 70 kg N ha−1”
Claim · model-written summary
The sufficiency-index approach yielded as much rice grain as four split applications of 80 or 120 kg N ha_1.
- Taxon
- riceOryza sativae0
- Treatment
- sufficiency index approache1
- Outcome
- grain yielde0
- Direction
- equivalente0
- Comparator
- applying 80 or 120 kg N ha_1 in four equal split dosese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It resulted in grain yield of rice equivalent to that produced by applying 80 or 120 kg N ha_1 in four equal split doses”
e1“Applying fertilizer N following sufficiency index approach”
Claim · model-written summary
LCC3-triggered N application yielded more rice than 80 kg N ha−1 applied in fixed splits.
- Taxon
- riceOryza sativae0
- Treatment
- Application of 30 kg N ha−1 whenever intensity of the color of the uppermost fully opened leaf of the rice plant was less than LCC shade 3 (LCC3)e0
- Outcome
- yieldse0
- Direction
- highere0
- Comparator
- application of 80 and 120 kg N ha−1 in four equal split doses at fixed timese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Application of 30 kg N ha−1 whenever intensity of the color of the uppermost fully opened leaf of the rice plant was less than LCC shade 3 (LCC3) resulted in higher yields than application of 80 and 120 kg N ha−1 in four equal split doses at fixed times”
Claim · model-written summary
LCC3-guided management had higher fertilizer N-use efficiency than LCC4-guided management.
- Treatment
- need-based N management using LCC3e0
- Outcome
- fertilizer N-use efficiencye0
- Direction
- highere0
- Comparator
- LCC 4e0
Not reportedTaxon
Verbatim
e0“higher fertilizer N-use efficiency was recorded with need-based N management using LCC3 rather than LCC 4 as critical color shade”
Claim · model-written summary
The authors recommend LCC3 to guide fertilizer N application for high yield and N-use efficiency.
- Taxon
- RiceOryza sativat0
- Outcome
- fertilizer N application should be guided by LCC3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“to obtain high yields and N-use efficiency, fertilizer N application should be guided by LCC3”
t0“Rice”
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