A Physiological Comparison of Modern Versus Obsolete Cultivars Under Water-Deficit Stress

There is a significant problem with the lack of uniformity in current yields. Recent literature and hypotheses indicate that the yield variability is mostly related to extreme environmental conditions but may also be influenced by a peak in genetic improvements for yield (Meredith, 1995). Comparative growth, dry matter partitioning, and yield of modern and obsolete cultivars have been studied (Meredith and Well, 1989); however little reference is made to the physiological differences between modern and obsolete cultivars. Therefore, the main objective of this study was to compare the physiological responses of modern versus obsolete cultivars to water-deficit stress conditions. This information may give additional insight into the development of cotton yields and help to formulate an explanation of why yields have become increasingly variable from year to year over the past few decades.