Quantifying the Interactive Effects of Carbon Dioxide, Low Temperature, and Ultraviolet-B Radiation on Cotton Root Morphology and Seedling Growth.

Abstract

With the projected change in global climate in the future, the interactive effects of multiple environmental stresses are predicted to have a negative effect on cotton growth and development. The increasing risk of climatological extremes including high CO₂, UV-B, and temperature fluctuations at early stages of cotton growth could lead to poor fiber quality and lint yield. The objectives of this study were to test the hypothesis that cotton cultivars differ in their response to multiple environmental factors of (CO₂) [400 and 750 µmol mol⁻¹ (+(CO₂)], temperature [28/20 and 20/12 °C (-T)], and UV-B radiation [0 and 10 kJ m⁻² d⁻¹ (+UV-B)]. Four cotton cultivars (TM1, DP1522 B2XF, PHY 496 W3R, and ST 4747 GLB2) were grown in eight sunlit, controlled environment chambers in which control treatment had 400 µmol mol⁻¹ [CO₂], 28/21 °C temperature, and 0 kJ UV-B. The results showed significant differences among the cultivars for most of the shoot and root parameters. Plants grown under low temperature alone or combination with +UV-B treatment caused more detrimental effects on root and shoot vigor. Even though the elevated CO₂ treatments ameliorated the damaging effects of higher UV-B levels on cotton cultivars, increased CO₂ couldn’t mask the negative effects of low temperature. The cotton cultivar TM1 had the lowest values for all the traits under CO₂, UV-B, and low temperature either alone or combination with other treatments. Based on the total stress response index (TSRI) developed for each cultivar over all treatments, four cultivars were classified as tolerant (DP1522 B2XF), intermediate (PHY 496 W3R and ST 4747 GLB2) and sensitive (TM1) to multiple environmental stresses. The variability among the cotton cultivars in their responses to multiple environmental stresses indicates the possibility of selecting best cultivars having the ability to cope with future climate change for a higher lint yield.