Effect of row spacing, growth stage, and nitrogen rate on spectral irradiance in winter wheat

Autor:	J. M. LaRuffa, William R. Raun, Marvin L. Stone, H. L. Lees, John B. Solie, S. B. Phillips, Gordon V. Johnson, E. V. Lukina
Rok vydání:	2000
Předmět:	Canopy Physiology Irradiance chemistry.chemical_element Forage Vegetation Nitrogen Normalized Difference Vegetation Index chemistry Agronomy Plant cover Mollisol Agronomy and Crop Science Mathematics
Zdroj:	Journal of Plant Nutrition. 23:103-122
ISSN:	1532-4087 0190-4167
DOI:	10.1080/01904160009382001
Popis:	Soil reflectance affects spectral irradiance measurements taken in winter wheat at early stages of growth when percent cover is low. The objective of this study was to determine the critical percent vegetation coverage needed for forage nitrogen (N) uptake calibration with indirect spectral irradiance measurements. Two field experiments were conducted at Tipton and Perkins, OK in October 1996. The effect of row spacing (15.2, 19.0, 25.4, and 30.5 cm) and growth stage (Feekes 4 and 5) under various N fertilizer rates (0, 56, 112, and 168 kg N ha‐1) on spectral irradiance measurements from wheat was evaluated. The normalized difference vegetative index (NDVI) was used to characterize wheat canopy irradiance. In general, NDVI decreased with increasing row spacing and increased with N fertilizer rate at Feekes growth stage 4. Row spacing and N rate were independent of each other since no significant interaction was found. High correlation (r=0.81–0.98) was observed between NDVI and vegetation coverag...
Databáze:	OpenAIRE
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