Submitted to: Physiologia Plantarum
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/5/2008
Publication Date: 8/1/2008
Citation: Deridder, B.P., Crafts-Brandner, S.J. 2008. Chilling stress response of post-emergent cotton seedlings. Physiologia Plantarum 134: 430-439 Interpretive Summary: Chilling temperatures often occur during the first few weeks after planting cotton in the arid Southwestern US. These episodes of cold temperature can negatively impact cotton during seed germination/emergence and during growth of post-emergent seedlings. We studied the chilling response specific to post-emergent 13-day-old cotton seedlings. We attempted to simulate field conditions by decreasing the air temperature gradually from 28 C to 10 C at the start of the night and then gradually rewarming the air temperature to 28 C during the first six hours of the day. Chilling for three consecutive cycles caused a reduction in growth that persisted even during a three day recovery period. Photosynthesis was impaired by chilling stress, but the biggest impact of chilling was on the expansion of the leaves. During the night-to-day transition the leaves of chilled plants wilted due to the inability of the roots to transport water to the shoots. This result was observed even when the roots were kept warm during the night. We conclude that leaf expansion was the most important factor determining the magnitude of the chilling response of post-emergent cotton seedlings. Selecting cultivars to withstand leaf wilting during the night-to-day transition may improve the chilling tolerance of cotton.
Technical Abstract: • Early season development of cotton is often impaired by sudden episodes of chilling temperature. We determined the chilling response specific to post-emergent 13-d-old cotton seedlings. • Seedlings were gradually chilled during the dark period and rewarmed during the night-to-day transition. For some chilled plants the soil temperature was maintained at control level. Plant growth, water relations, and net photosynthesis (Pn) were analyzed after 1 or 3 chilling cycles and after 3d of recovery. • Three chilling cycles led to lower relative growth rate (RGR) compared to controls during the recovery period, especially for plants with chilled shoots and roots. Treatment differences in RGR were associated with net assimilation rate rather than specific leaf area. Loss of leaf turgor during the night-to-day transition was closely associated with decreased leaf expansion for chilled seedlings. Pn was inhibited during chilling partially as a result of decreased Rubisco activation. However, Pn fully recovered after seedlings were returned to control conditions. • We conclude that leaf expansion was the most important factor determining the magnitude of the chilling response of post-emergent cotton seedlings.