Effects of calcium-ion concentration and ethylenediaminetetra-acetic acid on microbial retting of flax

Abstract

Treatment of flax stem sections with Ca2+ prior to inoculation with Epicoccum nigrum resulted in an increase in pectin lyase activity and the rate of retting was enhanced. Ca2+ applied 1 week after the herbicide glyphosate also enhanced the initial rate of pre-harvest retting of the standing crop but at the culmination of the experiment retting was not significantly different from that of the control stems which had only been treated with glyphosate. An increase in pectin lyase activity was detected in the Ca2+-treated standing crop, but both polygalacturonase and xylanase activities were suppressed. Treatment with EDTA significantly increased the rate of retting in vitro in stems inoculated with E. nigrum and also in the prematurely senescing standing crop. Enhanced polygalacturonase and xylanase activities were detected in EDTA-treated stems, with only an insignificant decrease in pectin lyase activity. No difference in types or frequencies (%) of fungi colonizing stems of the standing crop were detected between treatments.