Germination, Seed Maturity and Viability, and Field Emergence of Rescuegrass

Abstract

Rescuegrass (Bromus catharticus Vahl) seed was collected at maturity in 1987 from Stillwater and Chickasha to characterize dormancy and field emergence. The effects of seed origin, seed coat conditions, substrate moistening agents, and a moist pre-chilling or dry pre-heating on seed germination were evaluated. In 1988, maturity and viability of freshly harvested rescuegrass seed were also evaluated. Seed appeared to be affected by a coat dormancy released by potassium nitrate and an embryo dormancy released by pre-chilling. A pre-heating of the seed reinforced both types of dormancy and only caryopses (bare seed) were able to recover from this reinforced dormancy. Percent emergence from bare soil conditions was highest with October plantings, but total forage dry weight and seed production were highest with September plantings. Field emergence of rescuegrass in alfalfa (Medicago sativa L.) was highest with September planting and decreased as the planting time proceeded into fall and winter. Cutting condition of alfalfa did not influence emergence but did affect growth and development of rescuegrass. Highest dry matter and seed production resulted with early fall planting into uncut alfalfa.