Detection of leaf area expansion promoted by additional fertilizer application on farmer’s paddy fields using multispectral images

Naoyuki Hashimoto, Yuki Saito, Shuhei Yamamoto, Masayasu Maki, Koki Homma

    Research output: Contribution to journalArticlepeer-review

    Abstract

    To monitor the effect of additional fertilizer application, we measured leaf area expansion in farmer’s paddy fields using multispectral images (MS images) collected using unmanned aerial vehicles (UAV). Leaf area index (LAI) growth rate (LGR), which is defined as the slope of linear regression for time-series LAI, was used for evaluation. The image analysis, which considered fluctuations of solar radiation conditions, was applied to obtain LAI from images, and compared with LAI measured by LAI-2200. Three levels of ammonium sulfate (0, 10, 15 g m-2) were set as additional fertilizer treatments in 4 transplanted fields (2 Hitomebore, 2 Manamusume and 1 Datemasayume) and 4 direct seeded fields(Hitomebore)of a juridical agricultural union in Sendai (total 72 test plots, the area of which was 3 x 3 m). The additional fertilizer increased the number of panicles. However, there were no significant effects on the yield components. Both LAI-2200-based and MS-image-based LGRs at the center of the plot revealed significant effects only for the transplanted Hitomebore. However, significant effects were detected in both transplanted and direct seeded test plots in LGRs between the center and outside area (2 m from center) based on MS images. These results imply that the MS image by UAV can be used to monitor the effects of the fertilizer applied. The method will be useful to determine the optimal amount of fertilizer for each field by optimizing LAI growth.

    Original languageEnglish
    Pages (from-to)211-221
    Number of pages11
    JournalJapanese Journal of Crop Science
    Volume90
    Issue number2
    DOIs
    Publication statusPublished - 2021

    Keywords

    • Effect of fertilizer
    • Leaf area index
    • Paddy field
    • Remote sensing
    • Unmanned aerial vehicle

    ASJC Scopus subject areas

    • Food Science
    • Agronomy and Crop Science
    • Genetics

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