E3 Journal of Agricultural Research and Development
E3 Journal of Agricultural Research and Development Vol. 3 (1) pp. 007-013, March 2013; © E3 Journals; ISSN 2276-9897
Changes in cotton leaf pigmentation after abnormal exposure to sunlight
Ranjit Riar1 , Randy Wells1 * , Keith Edmisten1 , David Jordan1 , Jack Bacheler11 North Carolina State University, Department of Crop Science, Box 7620, Raleigh, NC 27695, USA
*Corresponding Author E-mail: Randy_Wells@ncsu.edu
Accepted 22 February 2013
Abstract
Leaves are adapted to respond differentially to changing light conditions and intensity. Cotton leaves are normally green during the growing season. However, mechanical manipulation or wind occasionally inverts leaves exposing the abaxial side to direct sunlight resulting in development of red pigmentation in otherwise green leaves. Based on this observation, this study was conducted to determine the effect of exposure of abaxial surface to direct sunlight on leaf pigmentation. Field experiments were conducted in 2007 and 2008. At 92 DAP, the quarter seized 0 to completely invert the leaf from its normal position. Inverting the T+2 leaves increased the anthocyanin concentration while causing a reduction in chlorophyll content. Chlorophyll to Anthocyanin ratio was lower in older inverted leaves with a reduced effect in the younger leaves. The abnormal exposure to direct sunlight caused the leaves to actively synthesize more anthocyanin. The data suggest that anthocyanin is synthesized as a photoprotectant that shields leaves from abnormal, excess radiation exposure.
Keywords: anthocyanin, chlorophyll. Cotton,
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