Barley and Durum Response to Seeding Rate at Maricopa and Yuma, 1996-97

Abstract

A poor stand as a result of a low seeding rate can cost the grower due to decreased yield potential. A seeding rate higher than optimum can also cost the grower not only due to increased seed cost but also due to increased susceptibility to water and nitrogen stress and frost damage. Seeding rates in small grains are usually expressed on a pound per acre basis, but since varieties differ in seed size, different amounts of seed can be planted at equivalent seeding rates. Defining optimum seeding rates are also complicated by the fact that the number of seeds that actually emerge can vary depending on planting conditions. In our studies, emergence varied from 50 to 100% emergence. At the Maricopa location, the optimum seeding rate was obtained with 12 seedlings per square foot, which corresponded to a seeding rate of 75 lbs /A for the small seeded Brooks wheat and 125 lbs seed /A for the large seeded Kronos durum. No differences in yield were detected at the Yuma Mesa location for barley seeding rates ranging from 75 to 150 lbs seed/A or at the Yuma - Valley location for durum seeding rates from 200 to 250 lbs seed/A. Growers generally seed at rates higher than the optimum suggested by this and other studies, but current commercial seeding rates are seen as cheap insurance against stand establishment problems and may or may not be warranted depending on seedbed conditions and percent emergence.