Phenotyping a diversity panel of quinoa using UAV-retrieved leaf area index, SPAD-based chlorophyll and a random forest approach

Jiale Jiang*, Kasper Johansen, Clara S. Stanschewski, Gordon Wellman, Magdi A.A. Mousa, Gabriele M. Fiene, Khalid A. Asiry, Mark Tester, Matthew F. McCabe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Given its high nutritional value and capacity to grow in harsh environments, quinoa has significant potential to address a range of food security concerns. Monitoring the development of phenotypic traits during field trials can provide insights into the varieties best suited to specific environmental conditions and management strategies. Unmanned aerial vehicles (UAVs) provide a promising means for phenotyping and offer the potential for new insights into relative plant performance. During a field trial exploring 141 quinoa accessions, a UAV-based multispectral camera was deployed to retrieve leaf area index (LAI) and SPAD-based chlorophyll across 378 control and 378 saline-irrigated plots using a random forest regression approach based on both individual spectral bands and 25 different vegetation indices (VIs) derived from the multispectral imagery. Results show that most VIs had stronger correlation with the LAI and SPAD-based chlorophyll measurements than individual bands. VIs including the red-edge band had high importance in SPAD-based chlorophyll predictions, while VIs including the near infrared band (but not the red-edge band) improved LAI prediction models. When applied to individual treatments (i.e. control or saline), the models trained using all data (i.e. both control and saline data) achieved high mapping accuracies for LAI (R2 = 0.977–0.980, RMSE = 0.119–0.167) and SPAD-based chlorophyll (R2 = 0.983–0.986, RMSE = 2.535–2.861). Overall, the study demonstrated that UAV-based remote sensing is not only useful for retrieving important phenotypic traits of quinoa, but that machine learning models trained on all available measurements can provide robust predictions for abiotic stress experiments.

Original languageEnglish (US)
Pages (from-to)961-983
Number of pages23
JournalPrecision Agriculture
Volume23
Issue number3
DOIs
StatePublished - Jun 2022

Bibliographical note

Funding Information:
Research reported herein was supported through a collaborative project between the King Abdallah University of Science and Technology (KAUST) and King Abdulaziz University (KAU) under grant numbers KAUST-OSR-3936 and KAUST-JP–19–005. The authors, therefore, acknowledge with thanks KAU & KAUST for their technical and financial support. We would also like to thank Omar Lopez Camargo, Samir AlMashharawi, Alejandra Barreto and Chunfeng Ma for their assistance during the data and field collection campaigns.

Publisher Copyright:
© 2021, The Author(s).

Keywords

  • Chlorophyll
  • Leaf area index (LAI)
  • Phenotyping
  • Quinoa
  • Random forest
  • Unmanned aerial vehicle (UAV)

ASJC Scopus subject areas

  • General Agricultural and Biological Sciences

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