| Potato is an all-purpose economic crop suitable to be as food, vegetable, feedstuff and industrial material. At the same time due to high yield, abundant nutrition and strong adaptability, potato distributes abroadly. However the yield and quality of potato would decline with its planting in successive years, which mainly results from degradation of potato for seed. To prevent from the degradation, using virus-free potato for seed is one of the effective measures. With industrializing course of potato quickening, more and more potato will be required, which could be solved effectively by industrializing produce of microtuber. Potato microtuber being of many merits, such as short producing cycle, easy controlling propagating process and so on, study on microtuber of potato has developed greatly. The experiment investigated into medium and photoperiod inducing microtuberization systematically, and main results are as follows.1. Effects of medium and methods of induction on microtuberizationA protocol by orthogonally design of L9 (34) is presented for investigation into the effects of table sugar, BA, B9, and NAA on microtuberization through direct and step-wise induction. The results indicated that under total darkness, as far as cv. Mira was concerned, the effect of step-wise induction was superior to that of direct induction in aspects of yield of microtuber, average weight per tuber and amount of tubers per flask. But compared with step-wise induction, the direct induction had an advantage of early tuberization. The medium of MS with 10% table sugar, 2mg/litre BA, 20mg/litre B9, and 1mg/litre NAA to induce microtuberization was the most optimum medium through step-wise induction. While through direct induction the medium of MS with 10% table sugar, 2mg/litre BA, 20mg/litre B9, and 1mg/litre NAA to induce microtuberization was the most optimum medium.2. Effect of photoperiod on microtuberizationThree varieties of Mira, Atlantic and Eshu-3 were induced to microtuberize under six different photoperiods of 0, 4, 8, 12, 16 and 24-hour in this experiment, whose results indicated that photoperiod had an effect on microtubers yield greatly. Optimum tuberization of Mira was obtained at 12-hour photoperiod and its number of microtubers per flask, weight per microbuber and yield perflask came to 13, 319mg and 4147mg respectively. And the lowest average weight per microtuber (187mg) and yield per flask (2543mg) were obtained in total darkness where its nuber of microtubers (13.6) per flask is the most. For cv. Atlantic the highest average number of microtubers (6.2) and yield (507mg) per flask were obtained in total darkness while the lowest average number of microtubers (1.3) in 16-hour photoperiod and yield (58 mg) per flask in total light were obtained. And for cv. Eshu-3 the highest average number of microtubers (6.2) in total darkness and the highest yield (1202mg) per flask under 4-hour photoperiod were obtained, while the lowest number (2.2) and yield (189 mg) per flask were obtained in total light. At the same time the effects of photoperiod on index of tuberization and ratio of R/T are same as effect of photoperiod on microtuber yield. The best photoperiods for Mira, Atlantic and Eshu-3 were 1 2-hour, 0-hour and 4-hour respectively.During inducing "tuberization conductance of medium became smaller with inductive time becoming longer. Under 0-hour, 4-hour, 8-hour photoperiods the longer photoperiod was, the higher the average chlorophyll content of plantlets was. While the difference of average chlorophyll contents between 12-hour, 16-hour, 24-hour photoperiods were not significant. Meanwhile time of induction becoming longer, chlorophyll content of plantlets in all photoperiods took on declining tendency. But the declining speed under 8-hour photoperiods was faster than that above 12-hour photoperiods.Furthermore the longer photoperiod was, the later initial time of tuberization of three cultivars was. That is to say, darkness was favorable to microtuberization but it was not one of nece...
|
PDF Full Text Request