Nitrogen Fertilization and Plant Growth Regulator Effects on Yield and Quality of Four Wheat Cultivars

Abstract

High rates of N fertilizer and the use of plant growth regulators (PGRs) to control lodging have combined to improve wheat (Triticum aestivum L.) yields in some studies and are often considered a part of intensive management systems. Our objective was to determine the effect of N rate and PGRs—chlormequat chloride (CCC) and ethephon—on soft red winter wheat yields, yield components, lodging, and baking and milling quality for flour characteristics under Indiana conditions. A split-split plot design was used with four soft red winter wheat cultivars—‘Arthur 71’, ‘Auburn’, ‘Caldwell’, and ‘Compton’—as whole plots; N rates 40, 80, 120, and 160 lb N/acre as subplots; and PGRs—CCC and ethephon—as sub-subplots. The studies were conducted on Parr silt loam (fine-loamy, mixed, mesic Typic Argiudolls). Cultivars varied in yield and yield components between the two years. Lodging was most severe with Arthur 71 and was minimal with Auburn both years. Nitrogen rates above 80 lb/acre were not beneficial in 1984. No yield response to N rates greater than 40 lb/acre occurred in 1985. N rates greater than 80 lb/acre increased lodging, decreased kernel size, and apparently reduced baking quality. Chlormequat chloride increased yields but only reduced lodging one year. Ethephon reduced lodging both years, but its detrimental effect on yield, kernel size, and baking quality detracted from its beneficial effect on lodging. Wheat yields were not increased when N rates were increased above recommended rates and PGRs were applied to control lodging.