Pulsed laser ablation: A new approach to reveal wheat outer layer properties

A new methodology based on pulsed lasers has been developed in order to estimate wheat outer layer mechanical properties without sample preparation. Laser experiments were carried out with an Argon Fluoride (λ = 193 nm) excimer laser source delivering pulses of 15 ns duration. Wheat grains from two cultivars were irradiated by single laser pulses with a quasi-uniform irradiation and two fluences (2.5 and 5 J cm−2). The ablation flux was characterized by environmental scanning electron microscopy before measuring the removed material on cross-sections observed by confocal scanning laser microscopy. Specific image treatment was carried out to obtain the ablation flux (amount of removed matter per pulse). Pericarp, seed coat and aleurone layer were gradually ablated under the laser conditions used in this work. Their ablation thresholds were different and could be related to tissue cohesion. Specific behaviour of seed coat layer (8 μm) could be emphasised with this technique. Pulsed laser ablation could be a potential methodology to reveal indirectly wheat grain layer cohesion.