Application of a Computer–Aided Image Analysis System to Evaluate Seed Germination under Different Environmental Conditions

BACKGROUND. Computer–aided image analysis tech-niques have been recently developed in monitoring seed imbibition. Their integration with the standard germination test is needed to describe the germina-tion performance of a seed sample with high accura-cy. METHODS. The image analysis system consists of two sets of components: a), an environmental system, which includes a thermostatic cell, a timer controlled transilluminator and a Petri dish containing the im-bibition medium and seeds; b), a computer imaging unit, which comprises a CCD-camera, a commercial computer and a software package that is able to cap-ture time-lapsed seed images and perform related size and shape measurements. RESULTS. The swelling process and germination on-set in broccoli, radish, lentil, lettuce and carrot have been assessed by monitoring changes in the image analysis parameters of seed size (area, perimeter, length and width) and seed shape (roundness factor). The time-course for each descriptor is similar to that of the triphasic curve of water uptake. Image record-ing, increase of area and roundness factor are used to determine timing of radicle emergence. The sys-tem can be applied to different germination condi-tions, such as salt stress and different temperature regimes, or to deteriorated seeds. Area and round-ness factor are also useful to estimate radicle elon-gation rate from protrusion time to the stage of vis-ible germination. CONCLUSIONS. The versatility and sensitivity of the new technique, together with the easiness of the in-vestigation of the germination behaviour in individ-ual seeds within a population, suggest that image analysis has a high application potential in seed qual-ity testing and biology studies. Key-words: seed imbibition, image analysis parame-ters, Brassica oleracea, Raphanus sativus, Lens culi-naris, Lactuca sativa, Daucus carot