Antioxidant metabolism in cotton seedlings exposed to temperature stress in the field

Early season temperature stress adversely affects the growth and development of cotton (Gossypium hirsutum L.) seedlings. Oxidative damage resulting from temperature extremes is thought to be a cause of diminished seedling performance. Cotton (cv Fibermax 958) was planted at Lubbock, TX, in 2003 and 2004 to investigate the effect of low and high temperatures on oxidative stress and antioxidant metabolism in seedlings exposed to normal thermal variation. Early and late plantings in 2003 provided seedlings of different ages for comparisons. Malondialdehyde was slightly increased in response to low temperatures indicating some oxidative damage in the seedlings. The activities of ascorbate peroxidase and glutathione reductase were not altered in response to low or high temperatures. The glutathione pool was predominately reduced in all plantings in both years indicating sufficient reduced glutathione. It is concluded that the indicators of antioxidant metabolism varied in the seedlings but not in response to temperature variation. It is proposed that antioxidant metabolism in the seedlings was sufficient to mitigate oxidative damage with only minor alterations.