PLANT-POPULATION AND HYBRID CONSIDERATIONS FOR DRYLAND CORN PRODUCTION ON DROUGHT-SUSCEPTIBLE SOILS

Selection of a target population for dryland corn (Zea mays) production on drought-susceptible soils is a difficult decision, as a stand appropriate for drought conditions may not fully utilize the environment during a non-stress year. One possible management strategy is to use a low seeding rate and hybrids with ear characteristics that promote yield stability over a range of environments and plant populations. To evaluate this strategy, a 2-yr field study was conducted on a Rumford loamy sand. The performance of four hybrids - 1) full season, flexible ear; 2) short season, flexible ear; 3) full season, prolific; and 4) short season, prolific - was evaluated at four populations - 29 600, 39 500, 49 400, and 59 300 plants ha(-1) - in two different growing seasons. Seasonal precipitation in 1988 was 14 cm below the average of 50 cm; 1989 seasonal precipitation was 37 cm above average. Average grain yields were 40% lower in 1988 than in 1989, and the yield loss was due primarily to a decrease in ear size. All hybrids demonstrated the ability to compensate for changes in population in 1988. Averaged across years, highest yields were produced with the two highest populations. The full-season, prolific hybrid was the most productive at every population.