Effects of Light and Temperature on Germination of Sideoats Grama

Abstract

Seed from three sources of sideoats grama (Bouteloua curtipendula (Michx.) Torr.) were planted on one- and two-way thermogradient plates to determine the effects of light, constant and alternating temperatures, and temperature duration on germination over a range of 10 to 40 degrees C. The direction of the temperature gradients was switched on various 24-hour cycles consisting of the following combinations: 4-20, 8-16, and 12-12 hours. Dormancy was not broken by any set of alternating temperature combinations. Light did not promote the rate or completeness of germination. The seed from various sources differed in the totality of germination over the entire thermogradient plate. The best germination over the entire plate was obtained with the 12-12 hour cycle, followed in turn by the 8-16 hour cycle and finally the 4-20 hour cycle for seed source 63, 1969 seed. As the imbalance of time cycles increased, the exposure of seed to continuous extreme temperatures increased also, thereby lowering total germination. Optimum temperatures for maximum germination of each source differed depending upon year of seed production and duration of the specific temperature.