Paper · 2025 · Plant Science Today

Calibration of leaf colour chart for need-based nitrogen management in Rabi maize under varied planting density in rainfed agriculture

Naik M Ramesh; S Hemalatha; A P K Reddy; et al.

9
claims
25
verbatim quotes
0
citations
2
research areas
✓
Open access · cc-by

Abstract

Efficient nitrogen management is critical to improving maize (Zea mays L.) productivity and sustainability under rainfed conditions, where excessive or untimely N use can result in environmental degradation and low nitrogen use efficiency (NUE). Two years of field studies were conducted during consecutive Rabi seasons (2017-18 and 2018-19) at the wetland Farm of S.V. Agricultural College, Tirupati, to calibrate the lead colour chart (LCC) for increasing grain yield, NUE and nutrient uptake under varied planting densities. The study intended to establish threshold leaf greenness values as practical guides for in-season, need based nitrogen top dressing in maize. A split-split plot design was used with three planting densities (66666, 83333 and 111111 plants ha-1), three nitrogen levels (30, 35 and 40 kg N ha-1) and three LCC thresholds (4, 4.5 and 5). Results showed that highest planting density (111111 plants ha-1) combined with 40 kg N ha-1 applied in splits based on LCC 5 significantly improved plant growth parameters, chlorophyll content, dry matter accumulation and kernel yield (5.36 t ha-1), along with enhanced nitrogen uptake (114.1 kg ha-1) and NUE (31.4 kg grain per kg N). Regression analysis revealed that dry weight (R² = 0.96), LAI (R² = 0.84) and NUE (R² = 0.70) were the strongest predictors of yield. LCC based nitrogen scheduling synchronized N supply with crop demand, minimized losses and improved soil N balance. These findings validate that LCC is an effective, ow cost tool for enhancing maize productivity and nutrient efficient under rainfed conditions.

Abstract from the paper’s OpenAlex record; open copy licensed cc-by. Read at the source ↗

The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.

Claims 9

Intervention effectobservedoriginal resultpositivesignificant (as stated)measured

Claim · model-written summary

Highest planting density with 40 kg N ha-1 applied on LCC 5 significantly increased maize kernel yield to 5.36 t ha-1.

Taxon
maizeZea mayst0
Treatment
highest planting density (111111 plants ha-1) combined with 40 kg N ha-1 applied in splits based on LCC 5e1
Outcome
kernel yielde1
Direction
improvede1
Value
5.36 t ha-1e1
Setting
wetland Farm of S.V. Agricultural College, Tirupatie0

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

t0

“Rabi maize”

✓ located verbatim in the source · title, characters 71–81 · show in text ↑
e0

“at the wetland Farm of S.V. Agricultural College, Tirupati”

✓ located verbatim in the source · abstract, characters 342–400 · show in text ↑
e1

“highest planting density (111111 plants ha-1) combined with 40 kg N ha-1 applied in splits based on LCC 5 significantly improved plant growth parameters, chlorophyll content, dry matter accumulation and kernel yield (5.36 t ha-1), along with enhanced nitrogen uptake (114.1 kg ha-1) and NUE (31.4 kg grain per kg N)”

✓ located verbatim in the source · abstract, characters 883–1198 · show in text ↑
Intervention effectobservedoriginal resultpositivesignificant (as stated)measured

Claim · model-written summary

Highest planting density with 40 kg N ha-1 on LCC 5 significantly improved plant growth parameters, chlorophyll content and dry matter accumulation in maize.

Taxon
maizeZea mayst0
Treatment
highest planting density (111111 plants ha-1) combined with 40 kg N ha-1 applied in splits based on LCC 5e1
Outcome
plant growth parameters, chlorophyll content, dry matter accumulatione1
Direction
improvede1
Setting
wetland Farm of S.V. Agricultural College, Tirupatie0

Not reportedComparatorValue

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

t0

“Rabi maize”

✓ located verbatim in the source · title, characters 71–81 · show in text ↑
e0

“at the wetland Farm of S.V. Agricultural College, Tirupati”

✓ located verbatim in the source · abstract, characters 342–400 · show in text ↑
e1

“highest planting density (111111 plants ha-1) combined with 40 kg N ha-1 applied in splits based on LCC 5 significantly improved plant growth parameters, chlorophyll content, dry matter accumulation and kernel yield (5.36 t ha-1), along with enhanced nitrogen uptake (114.1 kg ha-1) and NUE (31.4 kg grain per kg N)”

✓ located verbatim in the source · abstract, characters 883–1198 · show in text ↑
Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

Highest planting density with 40 kg N ha-1 on LCC 5 enhanced maize nitrogen uptake to 114.1 kg ha-1.

Taxon
maizeZea mayst0
Treatment
highest planting density (111111 plants ha-1) combined with 40 kg N ha-1 applied in splits based on LCC 5e1
Outcome
nitrogen uptakee1
Direction
enhancede1
Value
114.1 kg ha-1e1
Setting
wetland Farm of S.V. Agricultural College, Tirupatie0

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

t0

“Rabi maize”

✓ located verbatim in the source · title, characters 71–81 · show in text ↑
e0

“at the wetland Farm of S.V. Agricultural College, Tirupati”

✓ located verbatim in the source · abstract, characters 342–400 · show in text ↑
e1

“highest planting density (111111 plants ha-1) combined with 40 kg N ha-1 applied in splits based on LCC 5 significantly improved plant growth parameters, chlorophyll content, dry matter accumulation and kernel yield (5.36 t ha-1), along with enhanced nitrogen uptake (114.1 kg ha-1) and NUE (31.4 kg grain per kg N)”

✓ located verbatim in the source · abstract, characters 883–1198 · show in text ↑
Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

Highest planting density with 40 kg N ha-1 on LCC 5 enhanced maize nitrogen use efficiency to 31.4 kg grain per kg N.

Taxon
maizeZea mayst0
Treatment
highest planting density (111111 plants ha-1) combined with 40 kg N ha-1 applied in splits based on LCC 5e1
Outcome
NUEe1
Direction
enhancede1
Value
31.4 kg grain per kg Ne1
Setting
wetland Farm of S.V. Agricultural College, Tirupatie0

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

t0

“Rabi maize”

✓ located verbatim in the source · title, characters 71–81 · show in text ↑
e0

“at the wetland Farm of S.V. Agricultural College, Tirupati”

✓ located verbatim in the source · abstract, characters 342–400 · show in text ↑
e1

“highest planting density (111111 plants ha-1) combined with 40 kg N ha-1 applied in splits based on LCC 5 significantly improved plant growth parameters, chlorophyll content, dry matter accumulation and kernel yield (5.36 t ha-1), along with enhanced nitrogen uptake (114.1 kg ha-1) and NUE (31.4 kg grain per kg N)”

✓ located verbatim in the source · abstract, characters 883–1198 · show in text ↑
Associationobservedoriginal resultmeasured

Claim · model-written summary

Dry weight was the strongest predictor of maize yield, with R² = 0.96.

Taxon
maizeZea mayst0
Treatment
dry weighte5
Outcome
yielde5
Value
R² = 0.96e5
Setting
wetland Farm of S.V. Agricultural College, Tirupatie0

Not reportedDirection

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

t0

“Rabi maize”

✓ located verbatim in the source · title, characters 71–81 · show in text ↑
e0

“at the wetland Farm of S.V. Agricultural College, Tirupati”

✓ located verbatim in the source · abstract, characters 342–400 · show in text ↑
e5

“Regression analysis revealed that dry weight (R² = 0.96), LAI (R² = 0.84) and NUE (R² = 0.70) were the strongest predictors of yield”

✓ located verbatim in the source · abstract, characters 1200–1332 · show in text ↑
Associationobservedoriginal resultmeasured

Claim · model-written summary

LAI was a strong predictor of maize yield, with R² = 0.84.

Taxon
maizeZea mayst0
Treatment
LAIe5
Outcome
yielde5
Value
R² = 0.84e5
Setting
wetland Farm of S.V. Agricultural College, Tirupatie0

Not reportedDirection

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

t0

“Rabi maize”

✓ located verbatim in the source · title, characters 71–81 · show in text ↑
e0

“at the wetland Farm of S.V. Agricultural College, Tirupati”

✓ located verbatim in the source · abstract, characters 342–400 · show in text ↑
e5

“Regression analysis revealed that dry weight (R² = 0.96), LAI (R² = 0.84) and NUE (R² = 0.70) were the strongest predictors of yield”

✓ located verbatim in the source · abstract, characters 1200–1332 · show in text ↑
Associationobservedoriginal resultmeasured

Claim · model-written summary

NUE was a strong predictor of maize yield, with R² = 0.70.

Taxon
maizeZea mayst0
Treatment
NUEe5
Outcome
yielde5
Value
R² = 0.70e5
Setting
wetland Farm of S.V. Agricultural College, Tirupatie0

Not reportedDirection

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

t0

“Rabi maize”

✓ located verbatim in the source · title, characters 71–81 · show in text ↑
e0

“at the wetland Farm of S.V. Agricultural College, Tirupati”

✓ located verbatim in the source · abstract, characters 342–400 · show in text ↑
e5

“Regression analysis revealed that dry weight (R² = 0.96), LAI (R² = 0.84) and NUE (R² = 0.70) were the strongest predictors of yield”

✓ located verbatim in the source · abstract, characters 1200–1332 · show in text ↑
Recommendationauthor interpretationoriginal resultpositivebasis n/a

Claim · model-written summary

LCC is an effective, low-cost tool for enhancing maize productivity under rainfed conditions.

Taxon
maizeZea mayst0
Outcome
enhancing maize productivitye1
Setting
rainfed conditionse1

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

t0

“Rabi maize”

✓ located verbatim in the source · title, characters 71–81 · show in text ↑
e1

“These findings validate that LCC is an effective, ow cost tool for enhancing maize productivity and nutrient efficient under rainfed conditions”

✓ located verbatim in the source · abstract, characters 1450–1593 · show in text ↑
Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

LCC based nitrogen scheduling improved soil N balance in maize.

Taxon
maizeZea mayst0
Treatment
LCC based nitrogen schedulinge1
Outcome
soil N balancee1
Direction
improvede1

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Zea mays
Zea mays · TaxonAkwugo · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

t0

“Rabi maize”

✓ located verbatim in the source · title, characters 71–81 · show in text ↑
e1

“LCC based nitrogen scheduling synchronized N supply with crop demand, minimized losses and improved soil N balance”

✓ located verbatim in the source · abstract, characters 1334–1448 · show in text ↑

lead atom · nutrient: content · Zea mays (maize)Results differ

15 papers: 1 positive, 14 negative or no effect

14 in the opposite direction

  1. negative
  2. no effect
  3. negative

11 papers more in this group

See all 15 papers →

lead atom · yield · Zea mays (maize)Positive and negative results

4 papers: 2 positive, 2 negative or no effect

1 paper in the same direction as this paper · 2 in the opposite direction

  1. negative
  2. no effect
  3. positive
See all 4 papers →

lead atom · physiology: pigments · Zea mays (maize)Positive and negative results

5 papers: 2 positive, 3 negative or no effect

1 paper in the same direction as this paper · 3 in the opposite direction

  1. negative
  2. negative
  3. negative

1 paper more in this group

See all 5 papers →

density · nutrient: efficiency · Zea mays (maize)Positive and negative results

10 papers: 9 positive, 1 negative or no effect

8 papers in the same direction as this paper · 1 in the opposite direction

  1. no effect
  2. positive
  3. positive

6 papers more in this group

See all 10 papers →

density · physiology: pigments · Zea mays (maize)Positive and negative results

15 papers: 10 positive, 5 negative or no effect

9 papers in the same direction as this paper · 5 in the opposite direction

  1. negative
  2. negative
  3. negative

11 papers more in this group

See all 15 papers →

density · nutrient: content · Zea mays (maize)Positive and negative results

44 papers: 34 positive, 10 negative or no effect

33 papers in the same direction as this paper · 10 in the opposite direction

  1. no effect
  2. negative
  3. no effect

40 papers more in this group

See all 44 papers →

nitrogen · physiology: pigments · Zea mays (maize)Positive and negative results

126 papers: 112 positive, 14 negative or no effect

111 papers in the same direction as this paper · 13 in the opposite direction · 1 reporting no difference from an alternative

  1. negative
  2. negative
  3. no effect

122 papers more in this group

See all 126 papers →

nitrogen · nutrient: efficiency · Zea mays (maize)Positive and negative results

194 papers: 142 positive, 52 negative or no effect

141 papers in the same direction as this paper · 42 in the opposite direction · 10 reporting no difference from an alternative

  1. negative
  2. negative
  3. no effect

190 papers more in this group

See all 194 papers →

8 of 11 groups shown: named compounds and organisms first, then groups whose results differ (checked claim by claim), then those with positive and negative results, then the smaller groups.

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.