The obvious evolutionary reality is that persistent use of harvest weed seed control (HWSC) is a selection pressure for any mechanisms enabling L. rigidum seed to avoid HWSC. For example, seed shatters before grain harvest or a greater percentage of retained seed at a height below that at which the crop is cut in the harvesting operation.
Light is an important resource that crops and weeds compete for and so increased light interception by the crop can be used as a method of weed suppression in cereal crops. This research investigated the impact of altered availability of photosynthetically active radiation (PAR) (from crop row orientation or seeding rate) on the growth and fecundity of Lolium rigidum.
Transgenic glyphosate-resistant canola was first commercially grown in Western Australia (WA) in 2010, providing an opportunity to obtain important baseline data regarding the level of glyphosate resistance in weeds following the exclusive use of glyphosate for in-crop weed control. In this study, two surveys (2010 and 2011) were conducted across the 14 Mha of the grainbelt of WA.
α-Amylase in grass caryopses (seeds) is usually expressed upon commencement of germination and is rarely seen in dry, mature seeds. A heat-stable α-amylase activity was unexpectedly selected for expression in dry annual ryegrass (Lolium rigidum) seeds during targeted selection for low primary dormancy.
Lolium rigidum (annual or rigid ryegrass) is a widespread annual weed in cropping systems of southern Australia. Seeds exhibit dormancy at dispersal and require a period of dry after-ripening to release dormancy, before germination and emergence can occur.
This study investigated a possible link between seed dormancy and herbicide resistance status of Lolium rigidum (annual or rigid ryegrass). Mature seeds were collected from 406 populations across the 14-million hectare grain belt of southern Western Australia.
Glyphosate-resistance evolution in weeds is evident globally, especially in areas where transgenic glyphosate-resistant crops dominate. Resistance to glyphosate is currently known in 16 weed species, including rigid ryegrass in Australia.
Crop rows oriented at a right angle to sunlight direction (i.e., east–west within the winter cropping system in Western Australia) may suppress weed growth through greater shading of weeds in the interrow spaces.