About
  PDF
Full Text
(214 K)

Evaluation of Physiological Responses of Modern versus Obsolete Cotton Cultivars under Water-Deficit Stress for Explaining Yield Variability

R.S. Brown, D.M. Oosterhuis, A. Bibi, M. Arevalo, and D.L. Coker

ABSTRACT

Year-to-year variability in yield is a major concern in U.S. cotton production. It is speculated that the reason for this variability in yield is a combination of adverse environmental conditions, particularly during boll development, coupled with changes in breeding objectives over the past few decades. Field studies were conducted in 2001 and 2002 in northeast Arkansas and in northeast and northwest Arkansas in 2003 to investigate physiological responses of modern versus obsolete cultivars under water-deficit stress to help explain yield development and variability in cotton. Treatments consisted of four modern and four obsolete cultivars subjected to both well-watered and water-deficit conditions. The cultivars evaluated were ST 474, DP NuCotn33B, SG 747, Acala Maxxa (modern) and ST213, DP 16, Rex, Acala SJ2 (obsolete). Results from 2001 and 2002 indicated no differences between obsolete and modern cultivars or differences between water treatments for altering physiological responses or yield development. However, the 2001 and 2002 seasons received above average rainfall making conditions to test the research problem in the field difficult. The 2003 season experienced a brief period of water-stress at the northwest Arkansas test location allowing for an assessment of the physiological responses of modern versus obsolete cultivars to that stress. A few physiological measurements such as leaf protein and leaf membrane integrity indicated that obsolete cultivars were better adapted to the brief water-stress than the modern cultivars, however the differences were not significant. We believe that if the water-stress would have lasted one to two weeks longer into boll development more physiological differences between modern and obsolete cultivars would have arisen. Also, differences would have been observed at harvest with lint yields being higher for obsolete cultivars under water-stress conditions. Future research will continue in growth chamber environments in which the amount of water-stress, duration of water-stress and timing of water-stress can be controlled. We anticipate that this information along with information already collected should help to explain why modern cultivars have increased potential for such variable yields from year-to-year.





[Main TOC] | [TOC] | [TOC by Section] | [Search] | [Help]
Previous Page [Previous] [Next] Next Page

Document last modified 04/27/04