Development of rapid vigor testing method using urine sugar analysis paper for soybean (Glycine max L.)

Abstract

Seed vigor is one of the seed parameters that determine the quality of seed for successful crop production. ISTA congress of 1995 adopted the definition of seed vigor as "the sum total of those properties of the seed which determine the level of activity and performance of the seed or seed lot during germination and seedling emergence". Seed deterioration resulting from production and storage factors is the major cause of the differences in seed vigor that results in low seedling emergence. This research was conducted from January 2021 to February 2022, intending to develop a rapid soybean vigor test using Urine Sugar Analysis Paper(USAP), and it was composed of three experiments. Twelve soybean seeds lots/ varieties were obtained from Indonesian Center for Agricultural Biotechnology and Genetic Resource Research and Development(ICABIOGRAD) used only for experiment 3. Experiment 1 was to determine seed moisture content and soaking period for USAP, whereas experiment 2 was to optimize the soaking period by seed number. Soybean seeds of the Biosoy1 variety consisted of three levels (low, medium, and high viability with 35%, 64%, and 94% germination percentages, respectively) were used for the first and second experiments. Experiment 3 was conducted for comparing USAP with other seed quality tests by analyzing correlation and regression by using twelve soybean seeds lots/ varieties. The first experiment determined moisture content and soaking period for the USAP seed vigor test. It was arranged in a completely randomized design with one factor as the combination of three seed lots, two levels of seed moisture content (10- 12% and 13-14%), and four levels of the soaking period (0, 6, 8, and 10 hours). The second experiment was the optimization of the soaking period by seed number. It was arranged in a completely randomized design with one factor: combinations of three seed lots, three levels of seed numbers (50, 75, and 100 seeds), and the soaking period (four levels as 0, 6, 8, and 10 hours). The data were analyzed statistically by the Minitab software. The result showed that both combinations of 10-12% and 13-14% moisture content with the soaking period of 10 hours effectively differentiated the three seed lots into two vigor levels using USAP. Experiment 2 optimized the soaking period from 10 hours to 8 hours using 100 seeds. The USAP test showed a high negative correlation with germination percentage (r = -0.95), vigor index (r = -0.98.), mean germination time (r = -0.96), radicle emergence (r = -0.94), and a high positive correlation with electrical conductivity (r =0.88).The USAP method was only successful in differentiating the low vigor seed lot from both medium and high vigor ones, mainly based on protein leakage concentration on USAP. However, USAP was not effective to differentiate soybean seed lots based on the leakage of sugar or pH color changes. The color changes from pale yellow-green for higher vigor seed lot to light greenish-blue for low vigor. The USAP was effective for the soybean vigor test for the seed lot with 10-14% moisture content by soaking 100 seeds into 50 ml of distilled water for 8 hours. The USAP is a promising rapid vigor test method but needs further development.