Response of Three Oat Cultivars to N Fertilizer 1

Knowledge of cultivar response to N is helpful to the small grain grower, who can increase yields and profits, and to the small grain breeder, who can manipulate heritable traits to develop cultivars with improved response to N. The objective of this research was to identify morphological and physiological traits influencing grain yield response to N for three oat ( Avena sativa L.) cultivars that differed in height. The cultivars were grown at five rates of N fertilizer (0, 28, 56, 84, and 112 kg N/ha) in each of three environments. ‘Stout’ was relatively short and early‐maturing, while ‘Marathon’ and ‘Lodi’ were taller and later‐maturing. The experimental design was a split plot, with N rates as whole plots and cultivars as subpplots. Stout had the largest grain yield response to N (pattern of change across rates of N) because it had better responses for spikelets per panicle and weight per kernel. Consequently, Stout accumulated more dry matter after heading. Panicle number was not positively associated with differential grain yield response to N. Stout also had thicker, heavier leaves than Lodi and Marathon, but none of the three leaf traits measured appeared to contribute significantly to the differential grain yield response among the cultivars. Determining yield component responses to N could be useful in oat breeding programs that are attempting to release cultivars which respond well to highly productive environments. Lines with favorable responses for one or more yield components should be included in a crossing program for high yield response.