PLANTING DATE AND MOISTURE EFFECTS ON YIELD, QUALITY, AND ALKALINE-PROCESSING CHARACTERISTICS OF FOOD-GRADE MAIZE

Grain quality specifications for maize (Zea mays L.) have been established for several processing industries. Our objective was to investigate the effects of planting date and moisture level on grain yield, physical grain quality, and alkaline-processing characteristics of food-grade maize. Field experiments were conducted in 1988 and 1989 at the Texas A&M University Farm, Burleson County, Texas. Seven food-grade maize hybrids and one nonprocessing hybrid were grown with two planting dates (normal and delayed) and two moisture levels (irrigated and dryland). Delayed planting, averaged across years, decreased grain yield 15.2%, kernel weight 6.8%, kernel density 1.8%, and kernel hardness 4.4%. In 1988, the dryland treatment decreased grain yield 30.0%, kernel weight 15.2%, and kernel density 1.8%, and increased kernel protein 5%, but had no effect in 1989. Kernel hardness decreased 2.8% in 1988 with dryland treatment, but increased 4.5% in 1989. Hybrid effects varied with year for kernel weight, density, hardness, and protein. The nonprocessing hybrid (B73 x Mo17) produced high grain yield (7911 kg ha-1) and average kernel protein (109 g kg-1), but relatively low kernel weight (270 mg), density (1.06 g cm-3), and hardness (45.4%). Of the food-quality hybrids, none consistently outperformed the others in all categories. Alkaline-processing characteristics of the grain were affected by agronomic inputs. In general, nixtamal (i.e., cooked grain after alkaline processing) moisture increased due to delayed plantings and reduced soil water availability. Dry-matter loss exhibited no discernible trends. Pericarp removal (qualitatively scored) was greatly affected by hybrid; RX404 consistently outperformed all other hybrids.