Study On Differences Of Dormancy Characteristic In Distinct Levels Of Virus-free Seed Potato And Technical Methods For Dormancy Breaking

With three levels of seed potato vzrieties (pre-basic seed, basic seed and certified seed) of the Favorita,Mira and Zhongshu No.2 as materials, the experiment was conducted to study the differences of dormancy characteristic in distinct levels of seed potato and technical methods for dormancy breaking. The results were as follows.1. The dormancy characteristic of potato cultivars and distinct levels of virus-free seed potato had some differences. In the three used cultivars, the dormancy time (harvest period to days of germinate) of Zhongshu No.2 was shortest, and Mira was longest, pre-basic seed's dormancy time was longest, certified seed was shortest. Breeder seed's dormancy time of Zhongshu No.2 was 14.33 days and 19 days than the basic seed and certified seed, pre-basic seed's dormancy time of Favorita was 10.67 days and 16.34 days than the basic seed and certified seed, pre-basic seed's dormancy time of Mira was 10 days and 17.66 days than the basic seed and certified seed. The differences of distinct levels of seed potato's dormancy amplitude was consistent with the dormancy time, positively that not only the dormancy time of certified seed was short, but it's sprout degrees was relatively closely consistent; the dormancy time of breeder seed was long, and it's sprout degrees was not orderly.2. Along with the storage period extend and dormant gradually through, the physiological and biochemical activities of tuber are gradually active. Glutamine syntheses rose at first and in a stable higher level gradually later. Alpha amylase and inverts activity was rose at first, then decreased (the breeder seed of Mira had been rising). Glutamine syntheses, alpha amylase and inverts activities were that basic seed was higher than breeder seed, the top bud was higher than base bud, and it showed some of the top advantage. The Alpha amylase activity of potato tuber was higher than dormancy bud.3. In the process of germination of seed potato, endogenous hormones would occur series of changes. GA3 and IAA content of seed potato's top bud emerge a trend which rose at first and then declined, ZR content had been rising, but ABA content had a slightly dropped, after that it rose. The GA3,IAA and ZR content represented that basic seed was higher than breeder seed, but ABA content was opposite, pre-basic seed was higher than basic seed. For the distinct cultivars and levels of seed potato,GA3 content came to the highest time was discrepancy, general rule was that basic seed was earlier than the breeder seed, and Zhongshu No.2 was earlier than Favorita and Mira.4. In potato storage and germination process, protein and starch content of potato buber were gradually reduced, species breeder seed's protein and starch content of different periods were larger than basic seed, and in this period, soluble sugar content present first increased and then decreased trend, in the early secondary, soluble sugar content was slight difference between breeder seed and basic seed, and in mid-late, soluble sugar content of breeder seed was larger than the basic seed.5. Using appropriate concentrations of GA3 and thiourea to seed can all break dormancy, shorten the dormancy time, and improved sprout uniformity (shorter dormancy amplitude), overall, the effect of GA3 was better than thiourea, the appropriate concentration of GA3 was 20mg/L, the effect of 1% thiourea+20mg/L GA3 planting was better than GA3 and thiourea for seeding alone, and it showed some of the coordination effect. In the distinct cultivars and levels of seed potato, the performance regularity of the above effect was consistent.