Raising yield potential of wheat. I. Overview of a consortium approach and breeding strategies

Abstract

Theoretical considerations suggest that wheat yield potential could be increased by up to 50% through the genetic improvement of radiation use efficiency (RUE). However, to achieve agronomic impacts, structural and reproductive aspects of the crop must be improved in parallel. A Wheat Yield Consortium (WYC) has been convened that fosters linkage between ongoing research platforms in order to develop a cohesive portfolio of activities that will maximize the probability of impact in farmers' fields. Attempts to increase RUE will focus on improving the performance and regulation of Rubisco, introduction of C(4)-like traits such as CO(2)-concentrating mechanisms, improvement of light interception, and improvement of photosynthesis at the spike and whole canopy levels. For extra photo-assimilates to translate into increased grain yield, reproductive aspects of growth must be tailored to a range of agro-ecosystems to ensure that stable expression of a high harvest index (HI) is achieved. Adequate partitioning among plant organs will be critical to achieve favourable expression of HI, and to ensure that plants with heavier grain have strong enough stems and roots to avoid lodging. Trait-based hybridization strategies will aim to achieve their simultaneous expression in elite agronomic backgrounds, and wide crossing will be employed to augment genetic diversity where needed; for example, to introduce traits for improving RUE from wild species or C(4) crops. Genomic selection approaches will be employed, especially for difficult-to-phenotype traits. Genome-wide selection will be evaluated and is likely to complement crossing of complex but complementary traits by identifying favourable allele combinations among progeny. Products will be delivered to national wheat programmes worldwide via well-established international nursery systems and are expected to make a significant contribution to global food security.

Yield potential, potential yield and realized yield at farmer level of cereals with special reference to rice (<em>Oryza sativa</em> L.)

“…Yield potential (YP) can be expressed in its simplest form as a function of the light intercepted (LI) and radiation use efficiency (RUE), whose product is biomass and the partitioning of the biomass into grain yield; that is the harvest index (HI) (ratio of grains : above ground biomass): YP = LI × RUE × HI (Reynolds et al, 2011). Thus, estimation and the genetic enhancement of yield potential of crops are dependent on three basic parameters of LI, RUE and HI.…”

“…Poor adaptation can result in very low yield despite the expression of a significant crop biomass. The photosynthetic capacity of contemporary germplasm of wheat may not even be utilized efficiently if spike fertility is not optimized (Reynolds et al, 2011). Spike fertility of wheat can be improved by increasing the availability of assimilates to the developing spike (Fischer, 1985), thereby reducing the early abortion of grains (Miralles and Slafer, 2007) or by increasing grain weight (Duggen and Fowler, 2006).…”

“…In rice, 'source' limitation is indicated by insufficient provision of photosynthates at key developmental stages as only 40 % of the florets are fertilized and filled to become grains though potential spikelet number per panicle has increased markedly in new rice types (Reynolds et al, 2011). However, in wheat, while the 'sink' strength of grain and photosynthetic capacity may be more in balance, historic gains in wheat yield potential have been associated with increased photosynthesis (Fischer et al, 1998).…”

“…According to this definition, yield potential is not measured under ideal climatic environment so that yield potential may vary from region to region or environment to environment. Reynolds et al (2011) used the term potential yield instead of yield potential and defined it as 'the maximum yield of a given species or cultivar possible achievable under existing conditions of solar radiation flux density with all the other environmental factors considered to be optimal'. Thus, the potential yield is determined by the biological properties of the species or cultivar and radiation resources available for utilization.…”

Evaluations on the potential productivity of winter wheat based on agro-ecological zone in the world

“…Wheat provides one-fifth of the total caloric intake of the world population (Reynolds et al 2011) and is produced on an area of over 200 million hectares worldwide (Ortiz et al 2008). The area of winter wheat accounts for more than 80% of the total wheat-growing area.…”