2010

Seeds in the field experience wet-dry cycling that is akin to the well-studied commercial process of seed priming in which seeds are hydrated and then re-dried to standardise their germination characteristics.

Sequestration of paraquat away from its target site in the chloroplast has been proposed as a mechanism of paraquat resistance. However, no consensus has been reached as to where paraquat is sequestered. This study quantifies paraquat in leaf protoplasts of paraquat resistant (R) and susceptible (S) Lolium rigidum.

Twenty-two amino acid substitutions at seven conserved amino acid residues in the acetohydroxyacid synthase (AHAS) gene have been identified to date that confer target-site resistance to AHAS-inhibiting herbicides in biotypes of field-evolved resistant weed species.

Modern herbicides make major contributions to global food production by easily removing weeds and substituting for destructive soil cultivation. However, persistent herbicide selection of huge weed numbers across vast areas can result in the rapid evolution of herbicide resistance.

In a world of more than 6 billion people, humans heavily rely on the dependable cultivation of the global food grain crops: rice, wheat, soybeans, maize (and cotton for fiber). History shows that threats to food production have major repercussions, including famine, war, and civil unrest.

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.

Preventing the introduction of weeds into the farming system through sowing of clean seeds is an essential component of weed management. The weed seed contamination of cleaned grain and herbicide resistance levels of the recovered weed seeds were examined in a study conducted across 74 farms in the Western Australian grainbelt.

The smoke-derived compound karrikinolide (KAR1) shows significant potential as a trigger for the synchronous germination of seeds in a variety of plant-management contexts, from weed seeds in paddocks, to native seeds when restoring degraded lands. Understanding how KAR1 interacts with seed physiology is a necessary precursor to the development of the compound as an efficient and effective management tool. This study tested the ability of KAR1 to stimulate germination of seeds of the global agronomic weed Brassica tournefortii, at different hydration states, to gain insight into how the timing of KAR1 applications in the field should be managed relative to rain events.

Seed dormancy in wild Lolium rigidum Gaud (annual ryegrass) populations is highly variable and not well characterized at the biochemical level.

The physiological and biochemical bases of seed dormancy in Lolium rigidum (annual ryegrass) are largely unknown, and study of this process is complicated by the outcrossing nature of the species and the strong influence of environment on seed dormancy.