Studies on the Growth, Flowering, and Production of Female Sterile Flowers as Affected by Different Levels of Foliar Potassium in Solanum sisymbrifolium Lam: II. INTERACTION BETWEEN FOLIAR POTASSIUM AND APPLIED GIBBERELLIC ACID AND 6-FURFURYLAMINOPURINE

The morphogenetic effects including increased internode extensionand flowering with concomitant formation of female sterile flowersinduced by a relatively low content of potassium in S. sisymbrifoliumare enhanced by applying GA₃. In plants with a high K content,the growth regulator simulates all the effects of a low levelof K without influencing the K content. The morphogenetic effects induced by kinetin include a decreasein internode extension and flowering. The similarity betweenthe effects induced by applying kinetin and those resultingfrom a high level of K in the plant is evident from their mutualadditive effect observed. In plants with a low K content kinetininduced decrease in flowering, suppresses the formation of flowersremaining sterile, and there is a concomitant increment in fertileflowers.     

Studies on the Growth, Flowering, and Production of Female Sterile Flowers as Affected by Different Levels of Foliar Potassium in Solanum sisymbrifolium Lam: III. INTERACTION BETWEEN FOLIAR POTASSIUM AND APPLIED DAMINOZIDE, CHLORMEQUAT CHLORIDE, AND CHLORFLURECOL-METHYL

The extent of inhibition of stem elongation and the reducedflowering induced by growth retardants daminozide and chlormequatchloride depends upon the K content of the plants in S. sisymbrifolium.In plants with a low content of K, the decrease in length ofthe internodes and the enhanced development of the lateral shootsinduced by the two growth retardants is greater. In the reproductivephase, a decreased production of inflorescences and a diminutionin the number of flowers borne are accompanied by a slight increasein the number of fully developed flowers. The number of femalesterile flowers, characteristic of the low-K plants, drops significantly.Daminozide and chlormequat chloride not only reverse the morphogeneticeffects of a low level of K but they produce additive effectsin plants with a high K content. The chlorflurecol-methyl-induced elongation of the main axisis greater in the high-K plants but that of the lateral shootsis considerably more in the low-K plants. In the reproductivephase, flowering is slightly reduced but the development ofthe sterile flowers borne by plants with a low content of Kis not affected. Indeed, the effects of chlorflurecol-methylare inconsistent. The significance of these observations and of the results communicatedin Sections I and II of this report is discussed.     

Studies on the Production of Digitalis Cardenolides by Plant Tissue Culture: II. EFFECT OF LIGHT AND PLANT GROWTH SUBSTANCES ON DIGITOXIN FORMATION BY UNDIFFERENTIATED CELLS AND SHOOT-FORMING CULTURES OF DIGITALIS PURPUREA L. GROWN IN LIQUID MEDIA

Undifferentiated, highly chlorophyllous cell cultures; undifferentiated white cell cultures; green, shoot-forming cultures; and white, shoot-forming cultures of Digitalis purpurea L. were established and subcultured every 3 weeks in liquid media in the light or in the dark. The digitoxin content, the chlorophyll content, and the ribulose bisphosphate carboxylase activity of these cultures were assayed. The light-grown, green, shoot-forming cultures accumulated considerable amounts of digitoxin (about 20 to 40 micrograms per gram dry weight), and the white, shoot-forming cultures without chloroplasts accumulated about one-third that amount of digitoxin. The chlorophyll content and the ribulose bisphosphate carboxylase activity of the undifferentiated green cells were about the same as they were in the green, shoot-forming cultures, but the digitoxin content of the former was extremely low (about 0.05 to 0.2 microgram per gram dry weight), which is about the same as that in undifferentiated white cells without chloroplasts. Thus, it was concluded that the chloroplasts are not essential for the synthesis of digitoxin in Digitalis cells. The optimum concentrations of the tested compounds for accumulation of digitoxin were: benzyladenine, 0.01 to 1 milligram per liter; indoleacetic acid, 0.1 to 1 milligram per liter; α-naphthaleneacetic acid; 0.1 milligram per liter; and 2,4-dichlorophenoxyacetic acid, 0.01 milligram per liter.