Yield Estimation and Quality Evaluation of Sweet Potato Using Spectral Reflectance

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Yield Estimation and Quality Evaluation of Sweet
Potato Using Spectral Reflectance
SATO Muneharu, ISHIGURO Etsuji, ISHIKAWA Daitaro,
and SEKIOKA Shin-ichi Faculty of Agriculture,
Kagoshima University, Japan
Question Can we estimate yield quality of
sweet potato before harvest remotely? Answer
Yes. Observe spectral reflectance signatures and
use our model!
The total leaf areas, the numbers of leaves, the
nitrogen contents of leaves, and the root yields
of sweet potato plants were observed periodically
throughout their cultivation period. And before
digging up them, the spectral properties of their
canopies were measured with a handheld
spectroradiometer. Then the relationships among
these traits were analyzed. Some of the NDVI
models we had tried showed the close relation
with total leaf area, the amount of yield, and
the nitrogen content of leaves as well. This
result opens up the way for the practical use of
the spectral reflectance data in crop production.
Fig.1 Changes of the number of leaves of sweet
potato.
Fig.2. Relationship between the total leaf area
and the number of leaves.
Fig.3 Relationship between the total leaf area
and the yield.
NIVI Model ND520,710 (R520-R710)
/(R520R710)
Fig.4 Changes of spectral reflectance on the
leaves of sweet potato.
Fig.7. Relationship between the yield and
ND520,710 index
Fig.8. Relationship between the total leaf area
and ND520,710 index
Fig.5 First differential curves on spectral
reflectance.
Fig.9 Relationship between the nitrogen content
in leaf and ND770,660.
Fig.10 Relationship between the phosphorus
content in leaf and ND550,660.
Fig.11 Relationship between the potassium
content in leaf and ND740,660.
Fig.6 Secondary differential curves on spectral
reflectance.