ABSTRACT

Yields across the Cotton Belt increased steadily throughout the 1980's, but leveled off and even decreased in the 1990's. Of more concern, however, is the increased year-to-year variability. A clear understanding of why yields have leveled off the past decade and why increased variability from year-to-year has occurred is urgently needed. It is speculated that the reason for this decrease in yield is a combination of adverse environmental conditions, particularly during boll development, coupled with changes in breeding directions over the past few decades. To test this assumption a randomized slit-plot study was designed and conducted in northeast Arkansas to evaluate yield development of modern versus obsolete cultivars as influenced by the environment. Two years data has shown differences in yield and components of yield as related to contrasting cultivars, but no significant correlations to irrigation has occurred. This is due in part to adequate rainfall during peak boll development.