ENVIRONMENTAL CONTROL OF INITIATION OF THE INFLORESCENCE,REPRODUCTIVE STRUCTURES,AND PROLIFERATIONS IN POA BULBOSA

Youngner , Victor B. (U. California, Los Angeles.) Environmental control of initiation of the inflorescence, reproductive structures, and proliferations in Poa bulbosa. Amer. Jour. Bot. 47(9): 753–757. Illus. 1960.—Environmental factors controlling inflorescence initiation and development of inflorescence proliferations were studied using controlled environments. Inflorescence initiation was promoted by long days (16 hr.) following vernalization of 1 wk. or more'at 10°C. Normal florets developed under high temperatures (21°–27°C.) and long days following initiation. Bulbils developed in place of normal florets at short days (8 hr.) and low temperatures (ca.20°C, or below). Long days and low temperatures or short days and high temperatures produced panicles containing both bulbils and normal florets. Two flower-promoting stimuli are proposed; one promoting inflorescence initiation and the second promoting floret differentiation. Both stimuli appear to be quantitative in their mode of action.