https://iopscience.iop.org/article/10.1088/1755-1315/355/1/012073
Seed germination is a crucial process in the seed-plant life cycle and is also important for plant establishment in natural and agricultural ecosystems[8]. During germination, the seeds rapidly recover physically from maturation drying, resume a sustained intensity of metabolism, complete essential cellular events to allow the embryo to emerge and prepare for subsequent seedling growth[9]. Therefore, a germination test is an appropriate method to verify the ability of water containing UFBs water to promote physiological processes. Comparison experiments were performed using distilled water and water containing UFBs produced from each batch of distilled water[10]. Figure 1 shows the germination rate of soybean seed dipped in distilled water and distilled water containing UFBs for 1 h and 2 h.
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As shown in figure 1, three repetitive germination experiments showed that the germination rates of soybean seeds dipped in distilled water containing UFBs for 1 and 2 h were 10-20 percentage points greater than that of those dipped in distilled water; these results clearly verify the physiological effect of UFBs. The earlier germination might be explained by greater activities of germination-related enzymes, the early hydration of the membrane and greater molecular mobility of the bulk and hydration water fractions[11]. The difference reaches up to an average of 20-25% on the first day of germination. The dipped seed in distilled water containing UFBs was faster and more even germination. ROS (Reactive OxygenSpecies) caused by UFBs might play an important role in growth by facilitating the cell walls needed for cell extension [12]. As well as hydroxyl radicals produced in the cell wall during the extension of the radicle and the weakening of the endosperm in seeds [13]. On the other hand, ROS is capable of causing oxidative damage, against macromolecules so that it leads to lipid peroxidation, DNA damage and DNA breaking [14]. A sufficient amount of ROS is needed for practical applications. The appropriate amount of ROS will increase the physiological activity of living organisms. The increase in germination continued until the fifth day for the dipped seeds using UFB water. At day 3 to 5, the percentage of seed germination for those seeds dipped in distilled water containing UFBs reached about 10%. For those seeds dipped in distilled water containing UFBs with DO level of 20 ppm shows more uniform results. The growth of soybean seed are significant differences among the seed dipped in distilled water and dipped in distilled ware containing UFBs with DO level of 10 and 20 ppm. This is caused by the amount of ROS that has a positive correlation with the amount of oxygen UFBs in the water. Hydroxyl radicals formed by the collapse of microbubbles in dilute solutions and oxygen nanobubbles can also produce ROS in water [15].
Dipping treatments for 1 and 2h resulted in different results. Dipping seeds in both distilled water and distilled water containing UFBs for 2h resulted in higher results than 1 h. Soybean seeds are very susceptible to imbibition damage, which is influenced by a variety of seed characteristics. Soybean seeds with water content lower than 11% [16] or even 13% [17,18] are usually more susceptible to imbibition damage. Whereas the soybean seed cv. Argomulyo contained 8% of moisture content. The imbibition process is the process of absorption of water by seeds to completely hydrated. Seeds that experience dipping for more than 1 h might experience better hydration to reach the water requirements for germination than the lesser ones. Figure 2 shows the germination rate of soybean seed cv. Grobogan dipped in distilled water and distilled water containing UFBs for 1 h and 2 h. The germination rate in both treatments is less than 60%. Soybean seed cv. Grobogan is a soybean seed that has a long storage period. The longer storage period may result in a lower germination rate. Soybean seed germination decreases faster during storage than other grain crops [19]. Based on data from the Research Institute for Agricultural Biotechnology and Genetic Resources, seeds containing 12% moisture content have a shelf life of two years, the growth rate is 30%, while seeds containing 10% moisture content have 66% growth ability. The water content of the soybean seeds sample was 11%. It is considered that the water content and length of the storage period may relate to the growth ability. This result shows that on the first day the growth of the seed after being dipped in distilled water and distilled water containing UFBs are 0 and 1.3%. The higher germination rate was found for that seed dipped in distilled water containing UFBs 20 ppm at day 3 for 1h dipping time. There is no increase in germination rate after day 3. The similar result was found for those soybean seeds dipped in distilled water and distilled water containing UFBs for 2 h
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This study demonstrated the application of UFBs water for germination tests of seed. The germination rate of sample seeds dipped in the water containing UFBs were obviously higher than that in the distilled water. The use of UFBs water has a positive effect on enhancing germination rate for both different storage period of seeds.
