| Zostera marina is a perennial marine seed plant of Magnoliaceae, commonly found in offshore shallows, river inlets, etc., and lives in submerged water. Eelgrass has important ecological services such as water purification, protection of biodiversity, dike protection and disaster mitigation, carbon sequestration. In recent years, by the increase in the intensity of marine development and utilization and the impact of global climate change, seagrass bed resources show signs of increasing decline, China's seagrass beds degradation rate is also accelerated year by year, in this context, the protection and restoration of seagrass bed resources can not be delayed. At present, in addition to taking effective management measures to protect the existing seagrass beds, scientific restoration of seagrass beds through human intervention is also one of the important ways. Transplanting artificially cultivated seagrass seedlings for seagrass bed restoration is also a way to utilize the seeds efficiently, in which the evaluation of seed vigor status is the key to determine the germination rate and seedling establishment rate. Seed vigor is an important index for screening high germination rate, high seedling emergence rate and other high-quality varieties, and it is also the main index reflecting the rapid and neat emergence of seeds as well as the normal growth of seedlings. At present, the commonly used test methods for eelgrass seed vigor are low-temperature germination assay, conductivity assay, enzyme vigor assay and TTCH content assay. Low-temperature germination test is a commonly used method to determine seed vigor, but the method has certain limitations, and cannot reflect the real vigor level of seeds well, especially in eelgrass seeds, because the germination time needs more than 2 weeks, so the timeliness is poor; seedling growth determination, germination rate determination and other traditional methods for detecting seed vigor need to be verified by a large number of repetitive experiments, which requires a large amount of manpower, material resources and time, and also requires a large amount of investment in the development and development of eelgrass seeds. Conductivity measurement, enzyme activity measurement and seedling growth rate measurement need to be validated by a large number of repetitive tests, which requires a large investment of labor, material and time, and may also cause damage to the sample. Conductivity measurement and enzyme activity measurement are destructive testing methods, causing damage to the seeds to be tested. With the rapid development of technology, various kinds of non-contact, non-destructive, rapid seed viability testing methods have begun to emerge, such as non-invasive micro-measurement technology, near-infrared spectroscopy scanning analysis technology, hyperspectral imaging technology, electronic nose detection technology, etc. Among them, non-invasive micro-measurement technology is used to determine the seed viability by means of the sample. Among them, the non-damaging micro-measurement technology is to determine the seed vigor by measuring the ion or molecular flow rate of drops on the seed surface. This technique has the advantages of non-damage, multi-electrode, multi-angle, high sensitivity, high resolution, etc., and has been applied in a variety of plant research fields, such as plant salt resistance, plant pathology, and plant heavy metal resistance. In this study, we determined the Ca2+ flow rate and flow direction within eelgrass seeds with different activities obtained from drying treatment by a non-invasive microbolometer system to investigate the relationship between Ca2+ flow rate and eelgrass seed vigor, and to provide a new method for rapid, non-invasive, in vivo identification of eelgrass seed vigor. Prior knowledge of seed viability status is a crucial aspect of all artificial seedling cultivation, including eelgrass. In this study, eelgrass seeds were subjected to different degrees of drought stress for their special recalcitrant properties, and the same batch of eelgrass seeds was artificially treated to create differences in vigor. While different indicators were used to describe the physiological state of the seeds after the drying treatment, non-invasive micrometry was used to determine the Ca2+ flow rate of the seeds in order to investigate the relationship between eelgrass seed vigor and the Ca2+ flow rate. In this study, drying treatments were used to artificially create viability differences in eelgrass seeds from the same batch, totaling five drying times (0h,1h,2h,4h,8h) and 20 groups of samples. Germination rate, relative conductivity, water content as well as CAT activity and MDA content were determined. The non-invasive micro-measurement technology was utilized to explore the detection of eelgrass seed vigor, so as to carry out preliminary experiments and demonstration for the feasibility of seed vigor grading, and to lay the foundation for the construction of eelgrass seed vigor grading standard system. The results showed that: with the growth of treatment time, the germination rate gradually decreased and the relative conductivity increased, and the germination rate of seeds after 4h of treatment was 12% lower than that of untreated seeds, and the germination rate after 8h of treatment was significantly reduced, 68.7% lower than that of untreated seeds;; the catalase activity also changed significantly with the change of the treatment time; the Ca2+ was effluxed, and the rate of effluxed increased with the growth of treatment time, and the rate of effluxed increased with the growth of treatment time, and the rate of efflux increased with the increase of treatment time, and the rate of efflux increased with the increase of treatment time. The Ca2+ efflux, efflux rate increased with the growth of treatment time, and the germination rate and Ca2+ efflux flow rate were significantly negatively correlated, and the fitted linear equation was y = -0.1922x + 94.09, with an R2 of 0.8606. It was proved that the Ca2+ flow rate has the potential to be put into practical production as a kind of eelgrass seed vigor detection index, which provides a basis for the rapid and non-destructive method of identifying eelgrass seed vigor. |
