Innovative application of NIR-AOTF and MRI to study water behaviour in cut flower

Abstract

In order to study the water status of cut flowers, a comparison study was made between flowers stored in water and flowers stored «dry pack», by using a portable NIR (near infrared)-AOTF(acousto-optical tunable filter) instrument and MRI (magnetic resonance imaging). As model flower, Zantedeschia aethiopica (commercially known as Calla lily) was used. To predict the weight loss and water content by NIR-AOTF, cut flowers were dried in a cold room at 10°C (±1°C) and 85% (±5%) relative humidity (RH), and measured for weight loss. For MRI application, 4 and 20°C storage temperatures were used for flowers kept in water or dry; two stem sections, basal and middle, were measured. Significant correlation results for weight loss and water content ( R2 in calibration = 0.98 for estimated % of water loss and 0.96 for % of water content; R2 cv = 0.95 and 0.90) were obtained by NIR-AOTF spectra acquisitions. MRI detected vessel degradation in the stem of the water-stored flowers at 4°C but at 20°C in dry storage no vessel degradation appeared and images were correlated with dry matter values. The use of image software allowed the transformation of images in normalized population and pixel intensity, which gave hints about the potential use of these data to combine with NIR-AOTF data. NIR-AOTF, an easy-to-use and non destructive instrument, can be used to predict the vase life of cut flowers by measuring water content or weight loss. MRI is a powerful tool to identify the plugging of vessels but it is destructive; the image software used represents a useful tool to correlate MRI with NIR-AOTF to predict vessel plugging.