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item Ayala Silva, Tomas
item Akin, Danny
item Foulk, Jonn

Submitted to: Plant Growth Regulation Society of America Quarterly
Publication Type: Abstract Only
Publication Acceptance Date: 2/16/2004
Publication Date: 8/1/2004
Citation: Ayala Silva, T., Akin, D.E., Foulk, J.A., Dodd, R. 2004. Effect of growth regulators on yield and fiber quality and quantity in flax. 31st Annual Meeting Plant Growth Regulation Society of America. August 1-4, 2004. Charleston Riverview Hotel, Charleston, SC. p 26-27. ABSTRACT ONLY.

Interpretive Summary: The purpose of this study was to determine if growth regulators applied to flax plants were harmful or helpful to winter flax yields under South Atlantic conditions. Growth regulators have an important role in the biosynthesis of fiber in different crops, affecting both the quality and elongation. Preliminary data derived in this research has shown that the application of PGRs such as GA3 and IAA to flax could increase the yield and produce finer, stronger fiber. In particular, commerical application of 250 ppm of GA3 could be used to achieve higher yields and better quality of flax fiber even with less than optimal flax cultivars.

Technical Abstract: Growth regulators have an important role in the biosynthesis of fiber in different crops, affecting both the quality and elongation. In research on various fiber plants, Gibberellic acid (GA3) and indole-3-acetic acid (IAA) promoted growth in hemp, jute and kenaf and in cotton, especially fiber production and elongation. Application of IAA increased fiber elongation and lint yield in cotton. GA3 causes stem elongation and flowering inhibition in a variety of plants. Little information, however, is available on the effect of these growth promoters on flax. Growth regulators were diluted in a 10% ethanol solution to produce final working concentrations of 1.0 and 3.0 ppm for IAA and 125 and 250 ppm for GA3, containing 0.2% Tween-80. Control plants were sprayed with 10% ethanol solution. Two kg of dew-retted plants were processed through the USDA Flax Pilot Plant and Shirley Analyzer. The yield of fine fiber, as an assessment of retting efficiency, was calculated as a percent of the amount of carded fiber and of the initial amount of flax straw. Shirley-cleaned fibers were analyzed in triplicate for tensile strength, elongation, and fineness. Stem height was measured from shoot tip to soil surface and stem diameter was measured using a digital caliper at the mid-point of the stem. Data were also collected on chlorophyll content, yield, and flowering. GA3 treatment increased fine fiber yield by 13-14% and improved fiber fineness by 12-16% and decreased chlorophyll content, stem diameter, flowering and boll production over untreated controls. IAA increased fine fiber yield, chlorophyll content, and stem diameter, but decreased fiber strength, and fineness over untreated controls. Along with its effect on stem height and diameter, IAA also caused an increase in fiber yield but not as great as that of GA3. Fiber fineness of GA3 - treated samples was highly significant over those treated with IAA or the control. Spraying regulators GA3 or IAA increased flax fiber yield by 15-26% and fiber fineness by 20%. The prospect of increasing flax yield and fiber quality along with using growth regulators to compensate for shortcomings in the cultivars holds promise for improving flax production.