%A Experimental Cooperation Group of Seed-potato Production %T Studies on the Technique of Seed-Potato Production I. Production of Virus-free Initial Stock by Means of Stem Tip Culture Technique %0 Journal Article %D 1976 %J J Integr Plant Biol %R %P -${article.jieShuYe} %V 18 %N 3 %U {https://www.jipb.net/CN/abstract/article_24768.shtml} %8 %X This is a preliminary report on potato stem tip culture since 1974. It also presents how to carry out the socialist cooperation and a suggestion of prevention from potato degeneration by means of seed-potato production. Excised stem tips with 1–2 leaf primordia (usually less than 0.5 mm long) were cultured in vitro. The improved basic culture medium contained Muller's macro-nutrients plus micro-nutrients and onganic substances of "AES" A (Japanese Agricultural Experiment Station, Medium A) plus sucrose (20 g/l) and agar (7 g/l). The pH of the medium was adjusted to 5.7–5.8. GA3 (0.1 ppm), 6-BAP (0.05 ppm) and NAA (0.01–0.1 ppm) were added to the medium at the first cultural stage. Two weeks later, they were transfered to a basic medium minus plant growth regulators. The cul- tures were grown under a temperature between 20–30 ℃ and a light intensity of 1,000–3,000 Lux. Four types of developmental growth patterns were obtained. By using different methods for different growth patterns, better results could be achieved. Seedlings usually developed in three months. The rate of seedling formation was about 50% and sometimes even as high as 70%–80% in some varieties. By way of repeated systematic virus assays, including host plant test and serological test, eight varieties of virus-free potato plants are now available. After cutting the seedlings into segments (each segment bearing one leaf) and culturing them in the basic medium, the production of daughter plants was found to increase exponentially. The Production rate was 7–8 times per month. When 10 ppm B9 was added to the medium, the seedlings were found to be more healthy and much greener than those of the controls. This is beneficial for successive transplantation. The viability of the seedling was above 90%. Over ten thousands of virus-free seedlings and tubers have already distributed to several initial stook farm bases used as the basic stock.