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Research efforts have also focused on better understanding of the genetic basis of these phenotypic differences in early vigour and their interactions with the environment, with targeted breeding for more genetic improvement in cereal improvement programmes in Australia. These genes not only reduce plant height but also decrease cell size to reduce leaf size during early growth ( Botwright et al., 2005).Īgronomic improvement on early vigour is mainly through selection of larger seed size targeting bigger embryos and larger leaves (a wider and longer leaf) and longer coleoptiles. Besides this, the global deployment of gibberellin (GA)-insensitive dwarfing genes has been implicated in reductions in early vigour in modern cultivars ( Calderini et al., 1996 Ellis et al., 2004 Ellis et al., 2007). Rebetzke et al., 2008) and potentially large genotype×environment (G×E) interactions. Despite moderate heritability, all are influenced by strong environmental covariates through the maternal parent (e.g. Phenotypic differences in early vigour in wheat have largely been associated with variation in grain or embryo size, rate of seedling emergence, leaf dimensions (leaf width and leaf length) and specific leaf area (SLA) of seedling leaves, coleoptile length (for improved crop establishment), as well as coleoptile tiller production ( López-Castañeda et al., 1996 Richards and Lukacs, 2002). Numerous morphological factors of moderate-to-high heritability contribute to increased early vigour in wheat ( Richards, 2000 Rebetzke et al., 2008). Botwright et al., 2002), there is a lack of systematic quantification of the impact of early vigour across a range of climate conditions. Despite the promise of benefits through greater vigour (e.g. Whether early vigour leads to increased or decreased yield will depend on local climate conditions. However, greater early growth and water use may also reduce available soil water later in the season to worsen terminal drought, leading to reduced yields. Consequently, it has been shown that genotypes with higher early vigour produced higher biomass and grain yield ( Whan et al., 1991 Turner and Nicolas, 1998 Rebetzke and Richards, 1999 Botwright et al., 2002).
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Greater early vigour leads to faster leaf area development, reduces soil water loss via soil evaporation, increases competition with weeds ( López-Castañeda et al., 1995), and improves nutrient uptake ( Liao et al., 2004 Ryan et al., 2015). More efficient use of soil moisture at early wheat growing stages (before canopy closure) is considered crucial for higher grain yields.
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Wheat yield is often limited by insufficient rainfall around anthesis with a terminal drought during grain-filling ( Richards, 1991). In these regions, rainfall is winter dominant ( Rebetzke and Richards, 1999 Richards and Lukacs, 2002 Rebetzke et al., 2007) and coincides with early wheat growth (planted in mid-autumn to early winter). the amount of leaf area produced early in the season) has been considered an important trait for rainfed (water-limited) wheat especially in Mediterranean climate regions such as southern Australia. Soil PAWC could play a significant role in delivering the benefit of early vigour and would require particular attention.Įarly vigour or seedling vigour (i.e. Opportunities exists for development of early vigour wheat varieties for wetter sites.
#Asseng apsim rue wheat plus
Increase in yield was mainly from increase in biomass and grain number, and was reduced at sites with seasonal rainfall plus initial soil water <300 mm. Early vigour through selection of doubled early leaf sizes could increase yield by 16%. On a typical soil with plant available water capacity (PAWC) of 147 mm, simulated yield increase with early vigour associated with larger seed size was on average 4% higher compared with normal vigour wheat. Here, we present a modelling framework for simulating the impact of early vigour on wheat growth and yield at eight sites representing the major climate types in Australia. Whether early vigour can lead to improved water use efficiency and crop yields is strongly dependent on climate and management conditions across the entire growing season. However, early vigour is a genetically complex trait, and results from field experiments have been highly variable. Early vigour, or faster early leaf area development, has been considered an important trait for rainfed wheat in dryland regions such as Australia.