| The potato is important vegetable and grain crop, which is vegetabively propagated by tuber, thus ensuring highly seed potato quality is the most important to improve potato production. Potato microtuber possess several characteristics, for example, the tuber produced throught out the year, easy to transport, easily stored for long time, high efficiency in disease-free etc., but having higher price and lower propagation coefficient on the potato microtuber that leads to difficult to meet the demand of the basic seed potato. In the study, the potato in-vitro plant of "Yanshu 3" cultivar were used as the ecperimental material have been carried out the following tests in order to improve the propagation cofficient of potato microtuber. Firstly, the suitable microtuberization seedling age was determined; Secondly, determined the acid stress pH value and days were appropriate for inducing microtuberization; Finally, discussed the changes of sucrose and starch content, the SS, SSS and AGPase activity in the different organs of potato plant treatment by pH 3.0 value of acid stress during the potato microtuberization. The results showed:The time of microtuber initiation was shoter with extended seedling age. The best performance in seedling age was 50 days, the stage of potato microtuber initiation was 9 d, the biggest average weight was 162.9 mg of microtuber and the highest (1.9) number of microtuber per plant.The disease free plant in seedling age was 50 days with different value of pH and the time of acid stress. In all the treatment, the best performance was the disease free plant in seedling age was 50 days with subjected to pH 3.0 aqueous solution and 1 d acid stress, the stage of potato mirotuber initiation was 4 d, the average weight was 162.9 mg and the number of microtuber per plant was 3.2 in MS medium containing 60 g·L-1 sucrose. Effect of sucrose concentrations on in vitro plant induced microtuberization with acid stress. The plant with acid treatment can induce microtuberization in MS medium containing 30 g·L sucrose, the time of microtuber initiation was 13 d, while the untreated plants instead, but form the more the number of shoots. The microtuber can form in MS medium containing 60 g·L-1 sucrose, regardless of acid treatment or not, and the throught acid treatment plant was earlier 5 days compared with untreatment.Acid stress and sucrose concentration had no significant effect on starch content in plant leaves. During in vitro plant subjected acid stress, there was no significant difference in content of sucrose at leaves, but the SS, SSS and AGPase activity in leaves were increased significantly. The concentration of sucrose in leaves with acid stress during microtuberization was higher than untreatment, but instead of the activity of SS in MS medium containing 30 g ·L-1 and 60 g·L-1 sucrose. The activity of SS in the leaves with acid stress in the process of inducing microtuber was altenatley decreased and increased in MS medium containing 30 g·L-1 sucrose. But the activity of SS in the leaves with acid stress reduced gradually during the first 5 days of inducing microtuber, at 5-10 d was declined dramatically and at 10-15 d was increased rapidly, after 15 d decreased significantly in MS medium containing 60 g·L-1 sucrose. The activity of SSS in the leaves with acid stress in the process of inducing microtuber for first 5 days had a tendency to decrease firstly and aftert rising, then that is stabilized in MS medium containing 30 g·L-1 sucrose; But the activity of SSS in the leaves was showed the activity declined firstly and then rised during the first 5 days of inducing microtuber, and after that it was significantly declined in MS medium containing 60 g ·L-1 sucrose. The activity of AGPase in the leaves with acid stress in the process of inducing microtuber was showed the activity rised firstly and after decreased, then increased again in MS medium containing 30 g·L-1 sucrose; But the activity of AGPase in the leaves was alternately tendency to decrease and increase during first 10 days, after that declined significantly in MS medium containing 60 g·L-1 sucrose. |
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