Mid-Infrared Lifetime Imaging for Viability Evaluation of Lettuce Seeds Based on Time-Dependent Thermal Decay Characterization

Abstract

An infrared lifetime thermal imaging technique for the measurement of lettuce seed viability was evaluated. Thermal emission signals from mid-infrared images of healthy seeds and seeds aged for 24, 48, and 72 h were obtained and reconstructed using regression analysis. The emission signals were fitted with a two-term exponential model that had two amplitudes and two time variables as lifetime parameters. The lifetime thermal decay parameters were significantly different for seeds with different aging times. Single-seed viability was visualized using thermal lifetime images constructed from the calculated lifetime parameter values. The time-dependent thermal signal decay characteristics, along with the decay amplitude and delay time images, can be used to distinguish aged lettuce seeds from normal seeds.

Thermal and hyperspectral imaging for Norway spruce (Picea abies) seeds screening

“…Secondly, reflectance factor extraction is well defined in literature, whereas thermal imaging does not seem to have similar established background. For example, Kim et al (2013) have had similar infrared lifetime study with lettuce seeds where description of used data preprocessing and normalization methods lacked in detail. Here we performed normalization of thermal imaging data using similar approach as used in spectral reflectance factor estimations.…”

“…For those reasons, they are promising for various applications in seed industry and are already applied for quality assessment and product characterization (Tigabu et al, 2004;Ruiz-Altisent et al, 2010;Sankaran et al, 2010). Mid-infrared thermography has been proposed as a tool for viability evaluation of seeds (Kranner et al, 2010;Kim et al, 2013) while near infrared imaging can be used to determine several seed properties such as starch, protein, water, lignan contents (Kim et al, 2006;Cen and He, 2007), to differentiate cultivars and origins (Zhang et al, 2012;Gao et al, 2013;Kong et al, 2013) or to identify insect-damaged seeds (Singh et al, 2010).…”

Pest damage assessment in fruits and vegetables using thermal imaging

“…In particular, pest damage can be analysed either by generalized tests or specialized tests. Thermal imaging is a kind of non-destructive testing method for various agriculture products because of its simple, low cost, rapid assessment and reliable method [2,3].…”

Evaluation of wheat seeds by terahertz imaging

“…Conventional seed viability testing methods, such as the tetrazolium and standard germination tests, are destructive, time-consuming, and labor-intensive [3]. Seed producers and users are all looking for a fast and accurate detection method for the identification of seeds.…”

“…Area (1) and area (2) represent the germ of wheat seeds. Area(3) gives bad information about the third seed.…”