AGRONOMIC PRACTICES THAT AFFECT CORN KERNEL CHARACTERISTICS

Agronomic practices affect corn (Zea mays L.) grain yield and may affect physical and chemical characteristics of corn kernels. These characteristics affect feed, rood, and industrial uses of corn grain. Four Field experiments consisting of planting date and population combinations were conducted to determine the effect of these agronomic practices on grain yield, kernel N concentration, and kernel hardness. Kernel hardness was estimated by kernel weight, kernel density, and grinding resistance. A fixed ear hybrid, B73 x LH38, was used in all four experiments. Two of the four experiments also included LH119 x LH51, a flexible ear hybrid. Planting date affected yield in only one experiment. In this instance, delaying planting 4 wk decreased yield 55%. Yield reduction from planting delay was greater for B73 x LH38 than for LH119 x LH51. In two experiments, increasing population increased yield quadratrically; whereas, in the other two experiments the effect of population on yield was linear. No interaction between hybrid and population occurred. Delayed planting increased kernel N concentration in one experiment. In all four experiments, increasing population resulted in a linear decrease in kernel N concentration. Few effects from either planting date or population on kernel weight and density were found. Grinding resistance was increased by delayed planting in one experiment but was not affected by plant population in any of the four experiments. Inverse relationships between yield and important kernel physical and chemical characteristics were found. Emphasis on high yield may result in less desirable grain. End-users that require high grain quality may need to provide incentives to growers.