Early silique‐shedding wild radish (Raphanus raphanistrum L.) phenotypes persist in a long‐term harvest weed seed control managed field in Western Australia

Abstract

BACKGROUNDThis study introduces a wild radish population collected from Yelbeni in the Western Australian grainbelt that evolved an early silique abscission (shedding) trait to persist despite long‐term harvest weed seed control (HWSC) use. In 2017, field collected seed (known herein as Yelbeni) was compared to surrounding ruderal and field collected populations in a fully randomised common garden study.RESULTSThe Yelbeni population exhibited a higher rate of silique abscission when compared to the ruderal populations collected from the site before wheat (Triticum aestivum L.) harvest (assessed at soft dough stage, Zadoks 83). A similar common garden study was conducted in the subsequent season (2018) using progeny reproduced on a single site without stress. The HWSC selected progeny (Yelbeni P) shed 1048 (±288) siliques before wheat maturity at the soft dough stage (Zadoks 83) compared to 25 (±7) siliques from the pooled control populations. The Yelbeni P population only flowered 6 days earlier (FT50 as determined by log‐logistic analysis) than pooled control populations which is unlikely to fully account for the increased rate of silique abscission. The Yelbeni P population also located its lowest siliques below the lowest height for harvest interception (10 cm), which is likely to increase HWSC evasion. The mechanism inducing early silique shedding is yet to be determined, however wild radish is known for its significant genetic variability and has demonstrated its capacity to adapt to environmental and management stresses.CONCLUSIONThis study demonstrates that the repeated use of HWSC can lead to the selection of HWSC avoidance traits including early silique shedding before harvest and/or locating siliques below the harvest cutting height for interception.This article is protected by copyright. All rights reserved.