Growth and Development in Range Grasses. IV. Photoperiodic Responses in Twelve Geographic Strains of Side-Oats Grama

Abstract

1. Twelve strains of side-oats grama (Bouteloua curtipendula), originating over a latitudinal range of approximately 17⚬ from San Antonio, Texas, to Cannonball, North Dakota, have been grown for a 2-year period in the greenhouses at the University of Chicago. Their responses on Chicago natural daylength and on 9-, 13-, 16-, and 20-hour photoperiods have been analyzed. 2. Vegetative and flowering responses on the different photoperiods showed that three strains from southern Texas and southern Arizona consist almost entirely of intermediate or short-day plants, with an upper critical photoperiod for flowering between 14 and 16 hours. These strains flowered more vigorously on a 13-hour than on a 9-hour photoperiod. A North Dakota strain consists largely of long-day plants with a critical photoperiod of about 14 hours. The other eight strains, from Nebraska, Oklahoma, Kansas, and New Mexico, also include numerous long-day individuals, although the data suggest that the length of the critical photoperiod for ...