Some Factors Affecting the Growth of Young Embryo in Vitro (A. NATURAL SCIENCE)

1. For the growth of young embryos of Datura tatula in vitro, the optimum concentration of agar in the medium is 4.5g/l. 2. The optimum temperature is 35℃. 3. No effect of illumination of fluorescent lamps on the growth of the embryo is observed. 4. Embryos cultured on the agar surface of the medium develop the root more rapidly than those submerged in the medium do. 5. Among carbohydrates tested, sucrose is the best carbon source. Galactose, glucose, mannose, and raffinose are unfavorable. Fructose, lactose, maltose, mannitol, and xylose do not support the growth of the embryo. 6. The optimum pH value of the medium is 6.2. 7. Thiamine hydrochloride, riboflavin, para-aminobenzoic acid, folic acid, uracil, adenine sulfate, IAA, kinetin, and IAA-kinetin combinations have no growth-promoting activity in the young Datura embryo. A growth factor mixture (thiamine hydrochloride, pyridoxine hydrochloride, nicotinic acid, and glycine) added together with NH_4NO_3 is slightly effective. 8. Casein hydrolysate and vitamine- and salt-free one stimulate strongly the growth of embryo, peptone considerably, and tryptone and yeast extract slightly. Autoclaved DNA and RNA are rather inhibitory. The authors are indebted to Professor S. Imamura and Assistant Professor M. Hamada, Kyoto University, for their guidance and counsel during the course of this study