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Germination of Kochia prostrata Seed¹

Kochia prostrata (L.) Schrad. has shown potential as a valuable forage species for Artemisia rangelands in the western United States. Stands are relatively difficult to establish by direct seeding, while transplanted plants persist and have proved adapted on numerous Sites. The effects of temperature on the germination of K. prostrata seeds was studied by determining the influence of 55 constant and alternating temperature regimes on seed germination. The constant temperatures were 0, 2, and 5-degree increments, 5 through 40 C. Alternating temperature regimes consisted of 16 hours at each constant temperature and 8 hours daily at each higher constant temperature. The phenology of germination in relation to incubation temperature and time was studied, and three criteria for germination were developed: (a) root tip uncoiled, (b) hypocotyl arch raised, and (c) cotyledons spmd. Quadratic response surfaces and estimated percent germination with confidence limits were developed for each germination criterion. Kochia prostrata seeds readily uncoiled at a wide range of moist incubation temperatures, but seedling development was very slow at low temperatures (0 to 5 C) and seedling mortality occurred at high temperatures (40 to 50 C). Raising of the hypocotyl arch was determined to be a more appropriate criterion by which to judge germination of this species because it could be recognized as actual growth rather than an indication of imbibition. By this criterion, K. prostrata seeds attained 42% germination at temperatures considered, based on field monitoring on Artemisia rangelands, to be moderate seedbed temperatures.

Key Words: Criteria for germination • Quadratic response surfaces • Germination in relation to temperature

² Range scientists, USDA, ARS, Reno, Nevada; game biologist, Utah Div. of Wildlife Resources, Ephraim, Utah; and range scientist, Intermountain Forest and Range Exp. Stn., USDA, FS Reno, Nevada.

Received for publication November 24, 1980.