Evaluation of chicory seeds maturity by chlorophyll fluorescence imaging

Abstract

Chicory (Cichorium intybus L.) seed production includes sorting to remove foreign materials and non-viable seeds. A machine vision system was developed to monitor the fluorescence in order to detect the immature chicory seeds. It comprised a monochromatic light source, a highpass filter and a monochromatic CCD camera sensitive to red and infrared. With this device, blue light reflected by the seeds was blocked whilst red fluorescence was measured by the camera. A segmentation algorithm was designed to estimate separately the fluorescence intensities of the pappus, a crown of scales, and the main body of the pericarp. Experiments were carried out on five clones of cross-pollinated chicory plants used for seed production. Two hundred flower heads were labelled at flowering and harvested at different times during the maturation process expressed in "days after flowering" (DAF). Germination tests were performed according to the recommendations of the International Seed Testing Association to measure the germination percentage (GP) and the germination rate (GR), an indicator of seed vigour. Seed chlorophyll content diminished during maturation following a different logistic trend for the pappus and the pericarp. The GP increased from 18 DAF to reach its maximum value at 21 DAF, but the GR remained low until 30 DAF and increased afterwards. The potential of chlorophyll fluorescence to be used as an indicator of chicory seed vigour was the greatest between 21 and 36 DAF. The fluorescence is relative to the reflectance signal of a reference paper and multiplied by 60.

Integrating Optical Imaging Tools for Rapid and Non-invasive Characterization of Seed Quality: Tomato (Solanum lycopersicum L.) and Carrot (Daucus carota L.) as Study Cases

“…Chlorophyll fluorescence-based technology is centered on the capacity of chlorophyll, which is often present in seeds during their development to emit light in a slightly longer wavelength in relation to the light that was absorbed (Misra et al, 2012;Smolikova et al, 2017). Because chlorophyll degradation is usually observed at late steps of seed maturation (Smolikova et al, 2020), chlorophyll content and its fluorescence are inversely proportional to the seed maturity and, consequently, to its quality (Ooms and Destain, 2011).…”

Chlorophyll fluorescence for classification of tomato fruits by their maturity stage

“…Although it has already been demonstrated that the chlorophyll fluorescence induction can be used to predict the maturity stage of mango [14], papaya fruit [15], lemons [16] and chicory seeds [17]. Our study proved that an accurate classification of tomato fruit according to the maturity stage could be achieved by using chlorophyll fluorescence induction.…”

Can chlorophyll fluorescence be used to determine the optimal time to harvest rice seeds for long-term genebank storage?

“…CF analysis of seeds of Brassica oleracea L. showed that germination increased as CF decreased (Jalink et al , 1998a, b). Ooms and Destain (2011) showed a similar relationship for chicory ( Cicorium intybus L.). CF analysis is now used to improve overall seed lot quality for a range of species, by removing individual seeds that are less mature (Nijënstein, 2014 and references therein).…”