Abstract
AbstractDicamba-resistant (DR) kochia [Bassia scoparia(L.) A. J. Scott] has been reported in six U.S. states and one Canadian province. To develop effectiveB. scopariacontrol tactics, it is necessary to understand the seed germination pattern of DRB. scoparia. The objective of this study was to compare the germination characteristics of DR versus dicamba-susceptible (DS)B. scopariapopulations from Montana and Kansas under constant (5 to 35 C) and/or alternating temperatures (5/10 to 30/35 C). DRB. scoparialines from Montana were generated after three generations of recurrent selection of field-collected populations with dicamba. Seeds of DR or DS lines from Kansas were obtained after one generation of restricted self-pollination. DRB. scoparialines from both Montana and Kansas had a lower maximum cumulative germination than the DS lines across all temperature treatments. A majority of DRB. scoparialines from Montana showed a temperature-mediated seed germination response, with a higher thermal requirement (30 to 35 C or 25/30 to 30/35 C) to attain the maximum cumulative germination compared with DS lines. Germination rates at 5 to 30 C were lower for DR versus DSB. scoparialines from Kansas. All DR lines from Montana took more time than DS lines to initiate germination at 5 and 10 C or 5/10 and 20/25 C. Similarly, there was a delayed onset of germination of the DR versus DS line from Kansas at 5, 10, 15, and 20 C. Furthermore, the DRB. scopariafrom both Kansas and Montana had a slower germination pattern relative to the DSB. scoparia. Diversified crop rotations using winter wheat (Triticum aestivumL.), fall-sown cover crops, or early-spring planted crops (e.g., wheat or barley [Hordeum vulgareL.]) that are competitive against late-emergingB. scopariain conjunction with strategic tillage and late-season weed control tactics should be used to facilitate depletion of DRB. scopariaseedbanks.
Publisher
Cambridge University Press (CUP)
Subject
Plant Science,Agronomy and Crop Science