Open AccessChlorophyll a Fluorescence Parameters do not Detect Yield-limiting Injury from Sub-lethal Rates of 2,4-Dichlorophenoxyacetic Acid (2,4-D) in Cotton (Gossypium hirsutum)
Author(s) -
Seth A. Byrd,
John L. Snider,
Timothy L. Grey,
A. Stanley Culpepper,
Jared R. Whitaker,
Phillip M. Roberts,
Daryl R. Chastain,
Wesley M. Porter,
Guy Collins
Publication year - 2020
Publication title -
journal of experimental agriculture international
Language(s) - English
Resource type - Journals
ISSN - 2457-0591
DOI - 10.9734/jeai/2020/v42i130449
Subject(s) - chlorophyll fluorescence , fluorometer , randomized block design , gossypium , zoology , 2,4 dichlorophenoxyacetic acid , gossypium hirsutum , horticulture , growing season , yield (engineering) , biology , malvaceae , chlorophyll , fluorescence , botany , materials science , physics , quantum mechanics , metallurgy
Aims: Determine if the use of novel chlorophyll a fluorescence parameters could be utilized to predict yield loss of cotton exposed to sublethal rates of 2,4-dichlorophenoxyacetic acid (2,4-D) at various growth stages.
Study Design: All trials were arranged in a randomized complete block design with four replications. Treatment means were subjected to analysis of variance and linear regression was utilized to determine relationship between chlorophyll a parameters and yield.
Place and Duration of Study: University of Georgia Gibbs Farm in Tifton, GA, USA and the Sunbelt Agricultural Exposition in Moultrie, GA, USA during the 2013 growing season.
Methodology: Two sublethal rates of 2,4-D were applied to cotton at six distinct growth stages. The rates consisted of 2 g and 40 g ae ha-1 equivalent to 1/421 and 1/21 of the full rate (0.532 kg ae ha-1), respectively. The sublethal rates were applied to cotton at six growth stages, including the four leaf, nine leaf, first bloom, two, four and six weeks after first bloom growth stages. A fluorometer was used to obtain the fluorescence parameters Fv/Fm, ΦEO and PIABS from the uppermost fully expanded leaves at various intervals after 2,4-D exposure.
Results: Despite yield losses ranging from 20 – 90% of the non-treated control, no consistent patterns resulted from utilizing fluorescence transients to detect 2,4-D injury and overall instances of significant difference were minimal and typically not biologically relevant. In many cases, treatments exposed to 2,4-D that exhibited yield loss showed evidence of greater photosynthetic efficiency than the non-treated control. In the majority of instances, many of fluorescence parameters measured fell within ranges observed in previous studies in cotton produced under typical or non-stressed conditions.
Conclusion: While it has been proven as a valuable tool in other plant screening endeavors, chlorophyll a fluorescence were not able to detect the effects of sub-lethal rates of 2,4-D on cotton, even in instances that resulted in severe yield loss.