Fruiting efficiency: an alternative trait to further rise wheat yield

Abstract

Further improvements in wheat yields are critical, for which increases in grain number would be required. In the recent past, higher grain number was achieved through increased growth of the juvenile spikes before anthesis, due to the reduction in stem growth. As current cultivars have already an optimum height, alternatives must be identified for further increasing grain number. One of them is increasing fruiting efficiency (grains set per unit of spike dry weight at anthesis). Fruiting efficiency is the final outcome of the fate of floret development and differences in this trait within modern cultivars would be related to higher survival of floret primordia. Then there are two alternative physiological pathways to improve fruiting efficiency by allowing a normal development of most vulnerable floret primordia: an increased allocation of assimilates for the developing florets before anthesis, or reduced demand of the florets for maintaining their normal development. Both alternatives may be possible, and it might be critical to recognize which of them is the actual cause of differences in fruiting efficiency. When considering this trait in breeding we must be aware of potential trade‐offs and therefore it must be avoided that increases in fruiting efficiency be constitutively related to decreases in either spike dry weight at anthesis or grain weight. In this review we described fruiting efficiency and its physiological bases, analyzing genetic variation and considering potential drawbacks that must be taken into account to avoid increases in fruiting efficiency being compensated by other traits.

The effect of duration of the vegetative phase in irrigated semi-dwarf spring wheat on phenology, growth and potential yield across sowing dates at low latitude

“…Until now, this discussion has readily attributed differences between the cultivars to the initial differences in duration of the vegetative period. But fruiting efficiency, although a cultivar trait only recently studied in detail (Slafer et al, 2015), is considered to be determined by events during spike growth just before (20-30 days) and up to and for a few days after anthesis, and affecting the survival of growing florets and the setting of grains. However development appeared to be no slower in Cajeme in this period, despite the presence of PpdD1b, in fact it was slightly faster as judged by the interval flage leaf emergence to anthesis.…”

“…Spike dry matter at anthesis (SDM a ) points to a small (6%) but significant superiority of Cajeme relative to Yecora (Table 7); the values were highest with optimum sowings, and in favourable years (not shown), changes which were paralleled by those in GN. A more accurate measure of spike structure, owing to the larger sample size, could be chaff dry weight at maturity (Table 7), although the relationship of chaff dry weight to SDWa is subject to some poorly understood dry weight changes between SDW a and CDW (Abbate et al, 2012;Slafer et al, 2015). Thus going from the spikes just after anthesis to the chaff at maturity there was average 23% increase in weight.…”

“…This assumed an extinction coefficient of 0.40 for GAI and half of total solar radiation energy as being photosynthetically active; because of generally high GAI values RUE values were insensitive to the assumed value for the extinction coefficient. Following Abbate et al (2012) the ratio of GN to SDM a (grains/g) was calculated, this ratio now being defined as fruiting efficiency (Slafer et al, 2015). Finally in these experiments it was possible to calculate GDM as a% of the change in DM from anthesis to physiological maturity (DM pm − DMa).…”

Statistical Modeling of Phenotypic Plasticity under Abiotic Stress in Triticum durum L. and Triticum aestivum L. Genotypes

“…Although T. durum has better water and nutrients use efficiencies under high-yielding environments and it tolerates abiotic stress better than T. aestivum, it has lower grain yield than T. aestivum under low-yielding environments [21,40]; however, both wheat genotypes responded similarly to changes in abiotic stresses in this and other studies [20]. It was speculated [72] that the constitutively larger kernel weight in T. durum is associated with its lower fruiting efficiency when compared with T. aestivum; nevertheless, kernels m −2 in both genotypes was the most sensitive yield component to abiotic stress in this and other studies [39,73], presumably due to its larger plasticity and high heritability (Table 2). However, its negative relationships with grain protein content and micronutrients index (Figure 3) remains challenging.…”

Quantitative Trait Loci of Plant Attributes Related to Sorghum Grain Number Determination

“…This framework has been used in a number of previous studies to describe genotype and environmental differences in grain number in many species (Egli, 1998;Andrade et al, 1999;Vega et al, 2001). We also demonstrated that grain number was largely related to changes in P R and E G. While a number of studies have investigated variation in plant or canopy attributes linked to resource capture and growth and their relation to grain number (Blum et al, 1997;van Oosterom and Hammer, 2008;Hammer et al, 2010;George-Jaeggli et al, 2013), studies associated with P R and E G are limited Aisawi et al, 2015;Slafer et al, 2015). A relevant feature is that the ecophysiological model takes into account the common trade-off between grain number and individual grain weight (Sadras, 2007;Gambín and Borrás, 2011) by explicitly considering an individual assimilate availability per grain (Egli, 1998).…”