Influência da direção de semeadura do milho nas variáveis reflectância e índice de vegetação verde normalizado

Souza, Eduardo Godoy de; Orlando, Gracielle A.; Uribe-Opazo, Miguel Ángel; Silva, Edson Antônio da; Scharf, Peter C.

doi:10.1590/s1415-43662004000100012

Cited by 5 publications

(3 citation statements)

References 3 publications

(7 reference statements)

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“…Analyzing the influence of crop row orientation on vegetation indices, SOUZA et al (2004) concluded that NDVI variability increased when crops were sown in north-south rows. Thus, in this experiment, data collection was carried out on crops growing in north-south rows.…”

Section: Figure 1 Greenseeker Sensor Mounted On Soybean In R1 Stagementioning

confidence: 99%

“…Several studies have already shown that passive sensors are influenced by the time of day, since their measurements depend on the level of solar radiation (SOUZA et al, 2004;SOUZA et al, 2010;ERDLE et al, 2011). On the other hand, active sensors use their own light source and so have the ability to work at any time of day without interference from solar radiation or atmospheric variations (TRIMBLE, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Temporal Variability in Active Reflectance Sensor-Measured Ndvi in Soybean and Wheat Crops

et al. 2017

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ABSTRACT:Optimization of N management is one of the great challenges to be overcome in grain production, as it is directly related to productivity and can also cause environmental damage. Precision agriculture aims to solve this problem by applying nitrogen fertilizer at varying rates. Reflectance sensors are instruments capable of estimating N needs in various crops, including grain crops. However, it is not clear how these sensors perform under varying solar radiation and cloud cover, due to a lack of research on their temporal variability. Thus, this study examined the temporal variability of the NDVI (normalized difference vegetation index), as measured by an active reflectance sensor, in both soybean and wheat crops. The NDVI data were collected using a GreenSeeker sensor every 15 minutes over 12 or 14 consecutive hours. Incident solar radiation was recorded using an Instrutherm MES-100 pyranometer. In all experiments in soybean and wheat, NDVI was negatively influenced by irradiation, showing higher values at the beginning and end of the day. Changes in cloud cover also affected NDVI values during the experiments.

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Section: Figure 1 Greenseeker Sensor Mounted On Soybean In R1 Stagementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temporal Variability in Active Reflectance Sensor-Measured Ndvi in Soybean and Wheat Crops

et al. 2017

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“…Eduardo et al 2004compared rows planted in north-south and east-west directions and examined the amount of green light (r 550 ) reflected by plant leaves. Plants grown in a north-south direction had higher reflectance throughout the day and were less dependent on the time of day than rows planted in east-west rows (Eduardo et al, 2004). Mohammad and Mohammad (2002) measured the amount of solar radiation that penetrated to varying depths into the canopy of plant leaves and measured input radiation.…”

Section: Plant Populationmentioning

confidence: 99%

The Effects Of Planting Techniques On Maize Grain Yield And Silage Production

Kaufman¹

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oriented germs). Randomly planted kernels had the lowest kernel density but the highest percentage of starch. Grain yields again were greater for NS rows (12.0 vs. 11.6 metric tons/ha; P ≤ 0.01) due to 6.5% greater kernel weights (P ≤ 0.01). The higher plant population increased grain yield per hectare but decreased kernels per ear (P < 0.02). Regressed across all samples, each 1% added starch displaced 0.38% oil and 0.44% protein. Grain yields were greater for kernels specifically at planting and when grown in NS than in EW rows.

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Calibrating Reflectance Measurements to Predict Optimal Sidedress Nitrogen Rate for Corn

Scharf

Lory

2009

Agronomy Journal

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A gronomy J our n al • Volume 101, I s sue 3 • 2 0 0 9 615 ABSTRACT Optimal N fertilizer rate for corn (Zea mays L.) and other crops can vary substantially within and among fi elds. Current N management practices do not address this variability. Nitrogen-stressed corn refl ects more visible light than N-suffi cient corn, possibly providing a basis for diagnosing optimal sidedress N rate in a growing crop. Our objective was to calibrate refl ectance measurements to predict economically optimal N rate (EONR) of corn in Missouri. We conducted eight fi eld experiments with N rate treatments in which refl ectance was measured at the V6 growth stage in plots that had received 0, 110, or ≥220 kg N ha −1 at planting. Refl ectance was measured in eight wavebands (510-830 nm) using a passive radiometer in three orientations (straight down, angled forward, and angled diagonally across rows). Refl ectance ratios (relative to refl ectance from high-N plots) were necessary to produce good relationships with EONR. We observed r 2 from 0.56 to 0.76 between relative refl ectance and EONR for all visible (510-710 nm) wavelengths in all measurement orientations except 610 diagonal. Th e highest r 2 values were observed for relative 510-, 560-, and 710-nm refl ectance in the straight down orientation. Th e straight down orientation is preferable for use in fi eld applications because it gave predictions as good as or better than the other orientations, while avoiding the complexities associated with angled orientations. Combinations of wavelengths did not have a stronger relationship with EONR than individual visible wavelengths, but all visible/NIR ratios gave r 2 ≥ 0.43 in all orientations, with many above 0.6. Calibrations such as those presented here could be used to convert refl ectance measurements to N rate recommendations during variable-rate sidedressing of corn.

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Influência da direção de semeadura do milho nas variáveis reflectância e índice de vegetação verde normalizado

Cited by 5 publications

References 3 publications

Temporal Variability in Active Reflectance Sensor-Measured Ndvi in Soybean and Wheat Crops

Temporal Variability in Active Reflectance Sensor-Measured Ndvi in Soybean and Wheat Crops

The Effects Of Planting Techniques On Maize Grain Yield And Silage Production

Calibrating Reflectance Measurements to Predict Optimal Sidedress Nitrogen Rate for Corn

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