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International Journal of Agronomy
Volume 2016 (2016), Article ID 6463826, 11 pages
http://dx.doi.org/10.1155/2016/6463826
Research Article

Phytotoxicity and Benzoxazinone Concentration in Field Grown Cereal Rye (Secale cereale L.)

1Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
2Avoca, Inc., P.O. Box 129, 841 Avoca Farm Road, Merry Hill, NC 27957, USA
3Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695, USA
4Department of Crop Science, North Carolina State University, Raleigh, NC 27695, USA
5USDA-ARS, Natural Products Utilization Research Unit, University, MS 38677, USA

Received 5 October 2015; Revised 8 December 2015; Accepted 10 December 2015

Academic Editor: Othmane Merah

Copyright © 2016 C. La Hovary et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Winter rye (Secale cereale L.) is used as a cover crop because of the weed suppression potential of its mulch. To gain insight into the more effective use of rye as a cover crop we assessed changes in benzoxazinone (BX) levels in rye shoot tissue over the growing season. Four rye varieties were planted in the fall and samples harvested at intervals the following spring. Two different measures of phytotoxic compound content were taken. Seed germination bioassays were used as an estimate of total phytotoxic potential. Dilutions of shoot extracts were tested using two indicator species to compare the relative toxicity of tissue. In addition, BX (DIBOA, DIBOA-glycoside, and BOA) levels were directly determined using gas chromatography. Results showed that rye tissue harvested in March was the most toxic to indicator species, with toxicity decreasing thereafter. Likewise the BX concentration in rye shoot tissue increased early in the season and then decreased over time. Thus, phytotoxicity measured by bioassay and BX levels measured by GC have a similar but not identical temporal profile. The observed decrease in phytotoxic potential and plant BX levels in rye later in the season appears to correlate with the transition from vegetative to reproductive growth.