Predicting Blooming Day of Cut Lily through Wavelength Reflectance Analysis

Abstract

Domestic export cut lily flowers are expensive in Japan when they are in bud state that has not yet bloomed and when no leaf yellowing has occurred. Predicting the blooming day of domestic cut lily flowers is essential to increase their commodity value. Thermal imaging, spectroscopic technologies, and hyperspectral cameras have recently been used for quality prediction. This study uses a hyperspectral camera, reflectance of wavelength, and a support vector machine (SVM) to evaluate the predictability of blooming days of cut lily flowers. While examining spectra at wavelengths of 750–900 nm associated with pollination, the resultant reflectance was over 75% during six to four days before blooming and 30% on a blooming day, indicating a decline in their reflectance toward blooming. Furthermore, SVM classification models based on kernel function revealed that the quadratic SVM had the highest accuracy at 84.4%, while the coarse Gaussian SVM had the lowest accuracy at 34.4%. The most crucial wavelength for the quadratic SVM was 842.3 nm, which was associated with water. The quadratic SVM’s accuracy, verified using the area under the curve (ACU), was above 0.8, showing suitability for spectral classification based on blooming day prediction. Thus, this study shows that hyperspectral imaging can classify spectra based on the blooming day, indicating its potential to predict the blooming day, vase life, and quality of cut lily flowers.