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Abstract
Yields of the glucosinolate breakdown products, goitrin, volatile isothiocyanates, and thiocyanate were determined in long-stored roots of ‘Laurentian’ rutabaga [Brassica napus L. (Napobrassica group)] after preharvest treatments with 2 defoliants, ammonium peroxydisulfate (persulfate) at 0%, 0.5%, 0.75%, and 1.0% and (2-chloroethyl)phosphonic acid (ethephon) at 0 and 1000 mg/liter, applied in all combinations. Root fresh weight and the 3 glucosinolate breakdown products were significantly influenced by persulfate applications (main effects), but not by ethephon. While the volatile isothiocyanates decreased progressively with increasing persulfate concentrations, goitrin was increased with applications of 0.5% persulfate. Thiocyanate was increased by applications of 0.5% persulfate and by 0.75% persulfate combined with ethephon.
Abstract
The addition of 1.0% (wt/vol) ammonium peroxydisulfate to 0.125%, 0.25%, and 0.50% (wt/vol) ethephon sprays, applied before harvest to rutabaga (Brassica napus, Group Napobrassica Mill. cv. Laurentian) nearing commercial size, defoliated a greater percentage of leaves than would be anticipated from the effects of the individual components. Defoliation expressed on the logit scale was a linear function of the square root of the ethephon concentration, if ethephon was applied with or without ammonium peroxydisulfate. Chemical name used: (2-chloroethyl) phosphonic acid (ethephon).