title: A Novel Remote Sensing Approach for Prediction of Maize Yield Under Different Conditions of Nitrogen Fertilization.
abstract: Maize crop production is constrained worldwide by nitrogen (N) availability and particularly in poor tropical and subtropical soils. The development of affordable high-throughput crop monitoring and phenotyping techniques is key to improving maize cultivation under low-N fertilization. In this study several vegetation indices (VIs) derived from Red-Green-Blue (RGB) digital images at the leaf and canopy levels are proposed as low-cost tools for plant breeding and fertilization management. They were compared with the performance of the normalized difference vegetation index (NDVI) measured at ground level and from an aerial platform, as well as with leaf chlorophyll content (LCC) and other leaf composition and structural parameters at flowering stage. A set of 10 hybrids grown under five different nitrogen regimes and adequate water conditions were tested at the CIMMYT station of Harare (Zimbabwe). Grain yield and leaf N concentration across N fertilization levels were strongly predicted by most of these RGB indices (with R (2)~ 0.7), outperforming the prediction power of the NDVI and LCC. RGB indices also outperformed the NDVI when assessing genotypic differences in grain yield and leaf N concentration within a given level of N fertilization. The best predictor of leaf N concentration across the five N regimes was LCC but its performance within N treatments was inefficient. The leaf traits evaluated also seemed inefficient as phenotyping parameters. It is concluded that the adoption of RGB-based phenotyping techniques may significantly contribute to the progress of plant breeding and the appropriate management of fertilization.
authors.affiliation: Integrative Crop Ecophysiology Group, Plant Physiology Section, Faculty of Biology, University of Barcelona Barcelona, Spain.
authors.forename: Omar
authors.initials: O
authors.lastname: Vergara-Díaz
authors.affiliation: International Maize and Wheat Improvement Center, CIMMYT Southern Africa Regional Office Harare, Zimbabwe.
authors.forename: Mainassara A
authors.initials: MA
authors.lastname: Zaman-Allah
authors.affiliation: International Maize and Wheat Improvement Center, CIMMYT Southern Africa Regional Office Harare, Zimbabwe.
authors.forename: Benhildah
authors.initials: B
authors.lastname: Masuka
authors.affiliation: Laboratory for Research Methods in Quantitative Remote Sensing, QuantaLab, Institute for Sustainable Agriculture, National Research Council Cordoba, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Hornero
authors.affiliation: Laboratory for Research Methods in Quantitative Remote Sensing, QuantaLab, Institute for Sustainable Agriculture, National Research Council Cordoba, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Zarco-Tejada
authors.affiliation: International Maize and Wheat Improvement Center, CIMMYT Southern Africa Regional Office Harare, Zimbabwe.
authors.forename: Boddupalli M
authors.initials: BM
authors.lastname: Prasanna
authors.affiliation: International Maize and Wheat Improvement Center, CIMMYT Southern Africa Regional Office Harare, Zimbabwe.
authors.forename: Jill E
authors.initials: JE
authors.lastname: Cairns
authors.affiliation: Integrative Crop Ecophysiology Group, Plant Physiology Section, Faculty of Biology, University of Barcelona Barcelona, Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Araus
keywords: NDVI; RGB indices; breeding; crop management; field phenotyping; maize; nitrogen fertilization