GRAIN AMARANTH SEEDING DATES IN THE NORTHERN GREAT-PLAINS

An understanding of crop response to planting date is essential when e valuating a potential new crop. A field study was designed to determin e the optimum range of planting dates for dryland grain amaranth (Amar anthus cruentus L. and A. hypochondriacus L, x A. hybridus L,) in the Northern Great Plains. Four grain amaranth cultivars, diverse for plan t height and branching, were evaluated over four consecutive years fro m 1989 to 1992 at Prosper (46 degrees 58' N, 97 degrees 4' W, elevatio n 220 m) in North Dakota. Soil types at the test site are a complex of Perella (fine-silty, mixed, superactive, frigid Typic Endoaquolls) an d Beardon (fine-silty, mixed, superactive, frigid Aeric Calciaquolls), Four or five planting dates were selected, ranging from 1 May to 1 Ju ly at approximately 15-d intervals. Year-to-year differences in weathe r influenced the response of amaranth to planting date for grain yield , days to anthesis, harvest index, plant height, final plant populatio n, and lodging. Plants sown in mid-June produced the greatest grain yi eld in 1989 and 1990, when near- or above-average temperatures occurre d throughout most of the growing season. Seedling survival was greater with later planting dates in all years except 1989, when excellent st ands were achieved with all planting dates. Greatest yields in 1992, a n unusually cool year, were produced with May planting dates; in that gear, most plants sown in mid-June did not mature before first frost. Material planted on 1 July failed to mature in both 1991 and 1992, In years with near- or above-average temperatures, the mid-June planting date was best for maximizing both stand establishment and grain yield. Given the uncertainty in predicting weather conditions, planting in e arly June in the Northern Great Plains should achieve good stands and produce high grain yields, while minimizing the risk of yield loss ass ociated with cool conditions.