Research On Seed Vigor And Changes Of Cotyledons Physiological Indexes During Seed Germination At Different Position Of Soybean Canopy

Using Jinong15 and Jinong24 as experimental materials that the canopy was divided into five parts according to plant weight, that is, lower, lower-middle, middle, upper-middle and upper. The study analyzed the 100-seed weight, seed vigor and the changes of cotyledons content of soluble protein, content of soluble sugar, MDA content, absolute conductivity and antioxidant enzyme activities during germination. The results were as follows:The soybean 100-seed weight increased slightly and then decreased gradually with the increasing canopy, the upper ones being the lightest. The germination rate and germination potential were higher in the low and lower-middle and their vigor indexes were significantly higher than in the upper-middle and upper. Germination of 7 days, the stem diameter of seedling in the lower and lower-middle were significantly greater than in the upper-middle and upper.During germination, cotyledons content of soluble protein increased first and then decreased, and the cotyledons content of soluble sugar increased gradually with seedling growth; cotyledons MDA content and POD activities increased gradually, and absolute conductivity increased, and SOD activities and CAT activities increased first and then decreased with seedling growth.During germination at different position of canopy, cotyledons content of soluble protein and the cotyledons content of soluble sugar increased gradually with canopy from down to up; cotyledons MDA content increased gradually, and POD activities increased first and then decreased, and absolute conductivity, SOD activities and CAT activities decreased gradually with canopy from down to up.This paper indicated that the low and lower-middle part was the best part as its seed vigor was high, the seedlings robust, and cotyledons’ metabolism vigorous.