Refractive index and spectral reflection in three leaf categories of strawberry (Fragaria x ananassa Duch.)

A study was carried out to examine the refractive index (RI) and red (R), green (G) and blue (B) colour spectral reflection of strawberry (Fragaria x ananassa Duch.) leaves. Digital photographs and their respective refractive indices of thirty trifoliate leaves from three leaf categories, i.e. most recently mature trifoliate leaves (MRTL), old trifoliate leaves (OTL) and leaf spot disease-infected trifoliate leaves (LSTL) of strawberry cv. Chandler were analysed. The highest RI was found in OTL. The spectral reflection of R, G, B (R+G+B) and spectral indices of B/R, (R-B)/(R+B) and B/(R+G+B) were not significantly different (p<0.05) among the three leaf categories. Higher values were reported for the indices G/R and R/(R+G+B), and a low value for G/(R+G+B) in LSTL compared to other two leaf categories. The normalized difference index of [(G-R)/(G+R)]2 was higher in MRTL than OTL. There was no any significant relationship among RI and spectral reflection of strawberry leaves.

Tropical Agricultural Research Vol. 25 (2): 261 – 265 (2014)