Barley and Rigid Ryegrass (Lolium rigidum) Competition is Influenced by Crop Cultivar and Density

Abstract

Western Australian growers are adopting no-tillage farming systems, which have a greater reliance on integrated weed management systems that include competitive cultivars, high seeding rates, strategic fertilizer placement, and narrow row spacing. At the same time, they are sowing more of their barley area to cultivars with a semidwarf habit. This study compared six two-row, spring malting barley cultivars with different morphological traits at two dates of planting and three crop densities, with nil-added and added rigid ryegrass at five sites. Four cultivars, ‘Buloke’, ‘Flagship’, ‘Hamelin’, and ‘Vlamingh’, had an erect early growth habit; the other two, ‘Baudin’ and ‘Gairdner’, had a prostrate, semidwarf early growth habit. Increasing the density of rigid ryegrass plants from 16 to 125 plants/m2decreased barley grain yield by reducing crop biomass production, tiller number, grain number, and harvest index. Average grain weight was also reduced at most sites. The impact of competition on grain yield varied across sites and cultivars, but did not interact with date of planting. Baudin, Flagship, and Hamelin were more competitive with rigid ryegrass than Buloke, Gairdner, and Vlamingh. Differences in competitiveness between cultivars did not appear to be strongly related to morphological traits that affect light interception such as canopy closure, plant height, and tiller number. Differences in cultivar competitiveness were cultivar-specific and not generic. Rigid ryegrass productivity (dry matter and tiller number) tended to be lower under the more competitive cultivars. Increasing barley plant density increased grain yield, and reduced both rigid ryegrass dry matter and tiller number. Barley density had a larger impact on rigid ryegrass productivity than crop cultivar. The impact of barley density on reducing rigid ryegrass tiller number was larger with the first planting date than the second, and higher in the added rigid ryegrass plots than the nil-added plots. This study highlights the importance of high barley seeding rate for the integrated management of rigid ryegrass.

Occasional mouldboard ploughing slows evolution of resistance and reduces long-term weed populations in no-till systems

“…Weeds were maintained at relatively low levels (b10 plants m −2 ) for 20 years with the RMB treatment, highlighting its effectiveness for managing weed numbers in the long term (Medd et al, 1985;Lemerle et al, 1995;Paynter and Hills, 2009). There is little published information on the long-term effects of an occasional MB in the NT system on weed population dynamics.…”

Interferência de Raphanus sativus na produtividade de cultivares de soja

“…Estatura e índice de área foliar (IAF) elevados e rápida formação do dossel determinam, com grande frequência, culturas com HC superior (Callaway, 1992;Drews et al, 2009). Entretanto, diferenças na HC entre cultivares podem não se relacionar com características morfológicas que afetam a interceptação de luz, e sim serem específicas do cultivar e não genéricas (Paynter & Hills, 2009). …”

Wide Row Spacing and Rigid Ryegrass (Lolium rigidum) Competition Can Decrease Barley Yield

“…What we don't know is, do barley cultivars differ in their responsiveness to planting in wide rows and is the response influenced by weed competition? We know this to be the case in narrow rows (Paynter and Hills 2009), but not wide rows.…”

“…In particular, they are looking to manage rigid ryegrass, which is an important weed influencing the productivity of crops in Western Australia (Jones et al 2005). There are very few papers that report the competitiveness of different barley cultivars with rigid ryegrass other than Paynter and Hills (2009). Most weed competition studies have been done with oat (Avenua fatua L., Avena sativa L., or Avena sterilis L.).…”