NITROGEN FERTILIZATION AND PLANT GROWTH REGULATOR EFFECTS ON WINTER WHEAT YIELDS, GRAIN QUALITY, LODGING AND CHEMICAL COMPOSITION OF CULMS

JILL SUSAN KNAPP, Purdue University

Abstract

Proper rates and timing of nitrogen (N) fertilizer are necessary for maximum wheat (Triticum aestivum L. em Thell.) yields, lodging resistance and grain quality. Several rates and methods of N application were studied for two years to determine the most beneficial method of N application on soft red winter wheat in Indiana. The influence of plant growth regulators (PGR) on grain yield, grain quality, lodging and culm composition was studied to determine their effectiveness in maximizing grain production. Three cultivars of soft red winter wheat were treated with three rates of N and a combination of N timing and nitrapyrin application, giving six methods of N application. Optimum N rate varied but the highest rate was detrimental to yield and grain quality both years and increased lodging in one year. Method of application had no effect on yield although grain quality and lodging were affected by different treatments. Five cultivars of soft red winter wheat were treated with four rates of N and the plant growth regulators CCC and ethephon. Moderate N rates resulted in maximum yields and reduced lodging. Highest N rate reduced yields, grain quality and increased lodging both years. Growth regulators reduced plant height and lodging but had variable effects on yield and grain quality. Culm samples from three cultivars were taken from low and high N rates and plant growth regulator treatments shortly after anthesis both years. Sections of culms were analyzed for water-soluble carbohydrates, cellulose, hemicellulose, lignin, P and K. High N reduced cellulose, hemicellulose and lignin. Growth regulators had little effect on P and K. There appeared to be no consistent relationship between carbohydrates, lignin, P or K and lodging resistance.

Degree

Ph.D.

Subject Area

Agronomy

COinS