TITLE	Allelopathic interference of plant-water relationships by para-hydroxybenzoic acid
AUTHOR	Richard R. Barkosky Minot State University, 500 University Avenue West, Minot, North Dakota 58707, USA Frank A. Einhellig Southwest Missouri State University, 901 South National Avenue, Springfield, Missouri 65804, USA
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ABSTRACT	Soybean seedlings were used as the test species to investigate the effect of phydroxybenzoic acid (pHBA) on growth and plant-water relationships. Plants were grown in nutrient solution under greenhouse conditions and were subjected to pHBA through amendments to the growth medium. Treatments were initiated 10 days after germination and continued for either 14 or 28 days with stomatal conductance, water potential, and water use monitored periodically. At harvest, effects on growth were determined and, in the 28-day study, the carbon isotope ratio (13C : 12C) of leaf tissue was analyzed as an indicator of integrated effects on plant-water status. Soybean growth was significantly reduced by 0.5 mM pHBA, or higher concentrations, with the degree of inhibition being concentration dependent. Plants treated with 0.75 mM pHBA had significantly lower stomatal conductance, lower water potential, and less discrimination against 13C. Similar trends were apparent in 0.5 mM pHBA-treated plants. Interference with plant-water balance appears to be one mechanism of action of pHBA causing a reduction in plant growth.
KEYWORD	Allelochemical; Allelopathy; Carbon isotopes; phydroxybenzoic acid; Soybean; Water status;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 44 Number 1 January 2003, page 53-58, 6 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China