No abstract

Physiological index data and low-field nuclear magnetic resonance (LF-NMR) spectral data of rice seed samples from three varieties harvested in different years were collected through a combination of the standard germination test and an LF-NMR test. Three parameters of seed vigor: germination energy, germination percentage, and germination index, were calculated based on the physiological index data of the rice seed samples to determine their vigor over the years after harvest. LF-NMR Carr-Purcell-Meiboom-Gill (CPMG) sequence echo-peak data were used as the input, and rice seed vigor was used as the output to establish discriminative models using principal component analysis, support vector machine, logistic regression, K-nearest neighbor, artificial neural network, and Fisher’s linear discriminant. The results showed that models constructed using any algorithm, except for principal components analysis-algorithm distinguished between seeds with high and low vigor, while models constructed using Fisher’s linear discriminant algorithm gave the best results. This study provided a rapid, accurate, and non-destructive method to test rice seed vigor, offering theoretical support and a reference for rice seed-sorting and storage research.

This study aimed to investigate the effect of low-frequency high-voltage pulsed electric field (LFHV-PEF) treatment on the germination of aged rice seeds. Aged rice seeds were subjected to LFHV-PEF treatment with different electric field strengths, and low-field nuclear magnetic resonance (LF-NMR) was performed to acquire the LF-NMR data of rice seeds at different germination periods during a standard seed germination test to analyze their internal patterns of water state and distribution. Optimal treatment conditions were determined based on the physicochemical data collected during germination, and the improvements in seed vigor were verified. The findings indicated that during germination, the contents of bound and semi-bound water within the aged rice seeds initially increased and then decreased, whereas free water and total water contents increased continuously and rapidly. Side peaks were also observed within the seeds. Under the LFHV-PEF treatment, the semi-bound water within the seeds was more easily converted to free water, and the water absorption rate, germination potential, germination rate, germination index, and vigor index of these seeds improved. Further, the optimal electrical field strength was 12 kV. By analyzing the internal patterns of water state and distribution in seeds, the mechanism by which electric field treatment improved seed vigor was elucidated, thus, providing theoretical support and data evidence for research on water absorption during the germination of rice seeds, and methods for improving seed vigor.

To simplify the application of electrical impedance spectroscopy, the characteristic points were explored for noninvasive determination of the freezing damage in potatoes. Impedance experiments were conducted on the potato samples at room temperature (20°C), 0, −4, and −20°C. Samples of fresh, frozen, and freeze–thawed samples were analyzed. The results show that the shapes of the impedance spectroscopies were different in each of these samples. The characteristic points Zextra, Zintr, and Zcyt from electrical impedance spectroscopy are proposed to indicate the freezing damage level. The Zcyt value was considerably different for each state (1,939; 25,130; and 43 Ω, respectively). This indicates that Zcyt is a useful index for freezing damage classification and that Zcyt could indicate cell structure changes in thawed samples. Practical applications The morphological characteristic points of electrical impedance spectroscopy were used to evaluate the freezing injury of potatoes. This method provides a novel approach to study the changes in biological tissues. The method of using characteristic points is more convenient and effective than with an equivalent circuit. The Zcyt value could be used for detecting freezing injury in potatoes. Moreover, this method can be potentially applied for quality analysis of agricultural products.