Midseason Stalk Breakage in Corn As Affected by Crop Rotation, Hybrid, and Nitrogen Fertilizer Rate

In July of 1993 and 1994, southern Nebraska experienced devastating windstorms, with winds estimated to exceed 45 m s⁻¹. These storms resulted in severe brittle-snap of corn (Zea mays L.), with stalks breaking near the primary ear node in the basal portion of an elongating internode. In the storm path were several experiments established on a Hord silt loam (Cumulic Haplustolls) to determine the effect of selected management practices (crop rotation, hybrid selection, planting date, and N fertilization) on nitrate leaching to ground water from irrigated cropland. After the storms, the number of broken plants was determined in these experiments to evaluate how management practices influenced severity of the damage. In 1993, crop rotation, hybrid, planting date, and N fertilization, and their interactions, all affected the amount of brittle-snap. Treatments that resulted in more rapid growth (optimum to excess N rates, corn rotated with soybean [Glycine max (L.) Merr.], and early planting) increased the severity of damage. In continuous corn, 7% of the plants broke, compared with 33% for rotated corn; damage ranged from 4 to 33% among hybrids; and percent broken plants increased quadratically, from 8% for the 0 kg N ha⁻¹ treatment to 24% at N rates equal to or greater than 80 kg N ha⁻¹. Only the hybrid factor was significant in 1994. Amount of brittle-snap was related to stage of development (r = 0.55, n = 160, P < 0.001). The great difference in severity of damage among hybrids indicates that the current best management strategy to limit brittle-snap losses is to plant hybrids less prone to breakage. Alternative management strategies, such as late planting, suboptimal N rates, and continuous cropping of corn, all are known to limit yield regardless of windstorms. There is a need for greater knowledge of cell and tissue characteristics that render hybrids susceptible or resistant to brittle-snap. Also, methods for simulating brittlesnap are needed to foster effective selection for resistant lines in breeding programs. Joint contribution of the USDA-ARS and the Agric. Res. Div. of the Univ. of Nebraska; published as Journal Series no. 12547.