Difference On Seed Vigor Of Spring Wheat With Different Grain Weight

In order to explore the difference of seed vigor of spring wheat with different grain weight, the(2013-2014) experiment was conducted to study growth and evaluation of seedlings, PEG osmotic stress and artificial accelerated aging on seeds, researched the growth characteristics of spring wheat on different grain weight, discussed the germination characteristics, biological characteristics, drought resistance characteristics and storage capacity of spring wheat seed with different grain weight on two altitudes. It provided theoretical basis for the selection of high quality seed in production. The main results were as follows:1. The different varieties and different seeds weight had the significant difference on germination rate, germination index, vigor index and biological traits(P < 0.05). The germination rate in grain weight was: Medium seeds > Large seeds > Small seeds, the regular of Germination index was: Medium seeds > Small seeds > Large seeds, Vigor index presented: Medium seeds > Large seeds > Small seeds. The speed of germination rate of small seeds was faster, and that of germination rate was low, and that of seedling was smaller; The speed of germination rate of small seeds was low, that of germination rate was faster, and that of seedling was faster; Compared with the large seeds, the germination speed of medium grain seeds was relatively faster, the germination rate was higher and the seedling was larger. So the optimum seed type was medium grain seed.2. Studied drought resistance of Xinchun 26 with different seed weight on 1523 m. It showed that under the CK, 5 % and 25 % drought stress, seed germination index were as follows: medium seed > small seed > big seed; Germination rate had no obvious regularity; the higher the seed, the higher the activity index; Under the same concentration, root length was negatively correlated with seed size, leaf area and vice versa. The drought stress on grain weight of seedling showed obvious inhibitory effect; Low concentration of drought stress promoted the growth of wheat roots, High concentration inhibited seedling root length. In addition, the relational models were established between the concentration and the main components of different sizes seed. So the resistant to drought stress of large and medium seeds was higher than small seeds' drought tolerance.3. Vidor index, leaf area and root length in different sizes under two altitudes were reduced significantly, germination rate also decreased, but not significantly; Root length was the highest in 5%, root length of different size seeds were treated with 5 % and 15 % was significantly increased compared with control under high altitude, in the 5 % and 15 % were also longer than the control under low altitude, but there was no significant difference between 15 % and control; Root length was significantly decreased in the treatment of 25 % under low altitude. Vigor index and leaf area showed large grain > medium grain > small grain in different PEG treats under two altitude, and there were significant differences among the different size seeds; The root length is small grain > medium grain > large grain. The indexes at high altitude were significantly higher than those at low altitude in the same concentration and same size seeds. Different mass fraction of PEG stress inhibited seed germination of Xinchun 11. The ability of large grain seeds to resist drought stress was stronger than other seeds. High altitude seeds had higher drought resistance.4. Artificial accelerated ageing test showed that germination factors and biological traits significantly decreased with extended of aging time about different spring wheat with different grain weight both two altitude. Where large seeds germination rate, germination index and vigor index was declined biggest in aging nine-day', respectively it was decreased by 20 %, 36.67 %, 47.08 %, 67.37 % compared with the CK at high altitude, was reduced by 22 %?47.33 %?46.67 %?65.61 % at low altitude. The germination rate, germination potential and germination index of the seeds with the same aging time at two altitudes were: small seeds > medium seeds > large seeds, vigor index was: medium seeds > large seeds > small seeds, leaf length, leaf perimeter, root diameter, root surface area and root and shoot dry weight were: small seeds > medium seeds > large seeds. Indicators of high altitude were higher than the low altitude. It showed that medium seeds were the most suitable seed type in seed production. The vigor of altitude 1523 m was higher and the resistance to aging was stronger than that at 795 m altitude.