Floral Induction and Development in Ochard Grass

Abstract

Floral induction in orchard grass, defined as the initial chemical differentiation of the ready-to-flower condition, requires both short days (< 13 hrs.) and low temps. (< 10[degree]C). The 2 can be separated provided the short-day exposure precedes the low temp. Floral initiation and development, in contrast, require long days and higher temps. In the latitude of Iowa this spring-flowering grass is induced in the fall, by Nov. 1-15, but shows no morphological evidence of flower development until spring, when the day length is 14 hours and more. Induced plants were held in vegetative growth for 45 short days, then flowered promptly on long days.