Electrical Conductivity and Ethanol Release to Assess Red Rice Seed Vigor1

Abstract

To evaluate seed vigor, electrical conductivity and ethanol tests are fast and efficient methodologies. They have the potential to be used in several species, such as red rice. However, there are no protocols or information about their efficiency. Thus, the objective was to evaluate the efficiency, and define parameters of execution for electrical conductivity and ethanol tests, to evaluate the vigor of red rice seeds. The study was conducted using four lots of ‘BRS 901’ red rice, which was subjected to a germination test, as well as first count, accelerated aging, and field seedling emergence tests. The electrical conductivity test was performed with 25, 50, and 100 seeds soaked in 50 mL and 75 mL of water, at 25 °C and 30 °C, for 3, 6, 20, and 24 hours, respectively. The ethanol test was performed with 50 and 100 seeds soaked in a volume of water equivalent to 1.0, 1.5, 2.0, 2.5, and 3.0× the mass of the seed sample. To assess the vigor of red rice seeds, the electrical conductivity test is an efficient method when conducted with 50 seeds soaked in 50 mL of water at 25 °C for 20 hours. Meanwhile, the ethanol test is most effective when performed with 50 seeds, in a volume of water that is 2.5× the mass of the sample, at 40 °C for 24 hours.

Ethanol test as a determinant of physiological potential of forest species seeds: The case of Plathymenia reticulata Benth. (Leguminosae-Mimosoideae), a tree of interest for Atlantic Forest restoration

“…When evaluating electrical conductivity, we observed that the quantity of leachates increased progressively in the direction of the more degraded lots. Inversely proportional to the damage to cellular membranes (Barbosa et al, 2021). The electrical conductivity increase indicates that there was a gradual reduction in seed vigor, this being observed at the level of membrane systems.…”

“…The first in the sequence of events during seed deterioration is degradation of the mitochondrial membrane. Therefore, the ideal vigor test should be able to identify reduced seed vigor in the first stages, detecting subtle changes between lots (Barbosa et al, 2021).…”

“…A vigor test based on loss of mitochondrial membrane integrity is the ethanol test, which supplies important information on physiological problems related to deterioration, given that more deteriorated seeds produce more ethanol than less deteriorated seeds (Buckley and Buckley, 2009). This test has demonstrated as a promising method compatible with other vigor tests on cabbage (Kodde et al, 2012), malted barley (Buckley et al, 2016), corn (Onwimol et al, 2019), melon (Ornellas et al, 2020), red rice (Barbosa et al, 2021), watermelon, pepper, and radish (Kucukhuseyin et al, 2021). Optimization of ethanol analysis protocols may be an efficient alternative to determine the physiological potential of seeds.…”