Long‐term effect of different tillage systems on the emergence and demography of Bromus diandrus in rainfed cereal fields

Abstract

Summary The adoption of no‐tillage systems in semi‐arid cereal fields in northern Europe has resulted in difficulties in controlling Bromus diandrus. However, in some fields, lower densities are observed in continuous long‐term no‐tillage management than in other reduced tillage systems. A cumulative effect on the seedbank could promote changes in the period of seedling emergence and in population demography. This study evaluated the effect of long‐term mouldboard plough (MbP), chisel plough (ChP), subsoiler (SS) and no‐tillage (NT) on the population dynamics of B. diandrus. The work was carried out in a barley (Hordeum vulgare)–wheat (Triticum aestivum)–barley rotation during three seasons where these soil management systems had been applied for the last 22 years. Cumulative emergence (CE) and densities of B. diandrus followed a gradient of ChP > SS > NT > MbP. This cumulative effect over time resulted in significant differences in population demography. A previous hydrothermal emergence model developed for this species estimated the percentage of emergence prior to the date of sowing to be: 71%, 92% and 53% for the seasons 2008–2009, 2009–2010 and 2010–2011 respectively. Furthermore, the reduction in CE observed was on average 53% in SS, 92% in NT and 98% in MbP in comparison with that recorded in ChP. The long‐term effect of different tillage systems tended to cause changes to soil characteristics (photo‐inhibition of germination, soil temperature, water availability) affecting B. diandrus demography, reaching equilibrium in weed densities over years, which were significantly lower in MbP and NT than in ChP or SS.

Changes in weed flora under the influence of long term application of liming and reduced soil tillage

“…Furthermore, desirable effects of conservation tillage may include the reduction of energy requirements for weed control, carbon sequestration and mitigation of greenhouse gas emissions (Meyer-Aurich et al, 2006), because consequences of this intensive agriculture are now well known with an important increase of atmospheric CO 2 concentrations, water pollution and biodiversity loss (Gaba et al, 2014). Guinjuan et al (2016) indicate that no-tillage has resulted in difficulties in controlling certain weed species. Decreasing tillage intensity increased the amounts of weeds, particularly of meadow grass (Poa annua L.) (Seehusen et al, 2017).…”

Causative factors influencing epizoochorous dispersal of weed seeds by sheep and associated carcass contamination in southern Australia

“…Such conditions are also likely to expedite the growth and subsequent sale of lambs prior to the time of inflorescence emergence in causal weed species. Furthermore, cereal cropping practices, which create conditions favourable for annual grass invasion (Fleet and Gill, 2012; Recasens et al , 2016), tend to be less commonly used in TAS than in other states (Llewellyn et al , 2016). The interaction between temperature and state was an unexpected finding, possibly explained in part by the variation in abattoir data collection processes between states, since differences in temperature across Australia do not typically correspond with state boundaries.…”

“…(Fleet and Gill, 2012) and Bromus spp. (specifically B. diandrus ) proliferation (Recasens et al , 2016). Herbicide resistance is fast developing in many populations (Owen et al , 2015; Shergill et al , 2015), while increased seed dormancy in both species facilitates escape from pre‐sowing control, supporting germination within‐crop (Kleemann and Gill, 2013; Shergill et al , 2015).…”

“…(brome grass) have obtained greatest notoriety, due to their sharp seed rachis and long, fibrous awns (Kelly et al , 2018). Furthermore, herbicide resistance (Owen et al , 2015; Shergill et al , 2015), variable dormancy patterns (Fleet and Gill, 2012; Kleemann and Gill, 2013) and adaptation to farming practices in both species (Fleet and Gill, 2012; Recasens et al , 2016) have resulted in the spread of Hordeum spp. and Bromus spp.…”

Weed Dynamics in No-Till Rainfed Crops in Chaouia, Semi-Arid Morocco

“…Assuming no seed input into the system, germinable seedbanks under no-till decrease more rapidly than under conventional tillage. Reducing tillage may shift seedbank densities and weed communities from annual broadleaves to annual grasses and/or perennials (Aibar, 2006;El Brahli & Mrabet, 2000;Gulden et al, 2011;Jose Maria & Sans, 2011;Murphy et al, 2006;Nichols et al, 2015;Recasens et al, 2016).…”