Grain Weight Response to Different Postflowering Source:Sink Ratios in Modern High‐Yielding Argentinean Wheats Differing in Spike Fruiting Efficiency

Abstract

Improving wheat (Triticum aestivum L.) yield potential via higher grain number per unit area (GN) may reduce average grain weight and consequently the yield increment would be low. Thirty‐nine high‐yielding modern cultivars differing in spike fruiting efficiency (FE) (number of grains per gram of no‐grain spike) were grown under potential conditions during two temperature‐contrasting years to study the level of source limitation during grain filling and rank the main physiological determinants of potential grain weight (PGW) and actual grain weight. The response of grain weight to a 100% higher source ranged from 0 to 25%, depending on cultivar and year. No general relationship was observed between PGW and FE. The stabilized grain water content, which was partially correlated with the endosperm cell number per grain (r2 = 48%, p < 0.05), was the main variable associated to grain weight variation (r2 = 77%, p < 0.00001) in both temperate and warm years. Genetic improvement focused on increasing the sink strength through higher GN is still an alternative to increase yield potential in modern cultivars as no source limitation during grain filling was observed. The improvement of FE could be used to increase GN and yield as no general negative relationship was observed between PGW and FE.

Uncovering the Genetic Architecture of Fruiting Efficiency in Bread Wheat: A Viable Alternative to Increase Yield Potential

“…3d). These results are in line with those reported by González et al (2014), who tested a set of Argentinean high‐yielding cultivars. Our results are in disagreement with Ferrante et al (2012) and Terrile et al (2017), but these studies had low genetic diversity with only four and two cultivars, respectively.…”

“…This agreed with the earlier study performed by Neumann et al (2011), who reported wide phenotypic variation in this wheat panel for several agronomic traits in a different environment. Particularly, FE showed a range of variation greater than the ones recently reported (Lázaro and Abbate, 2012;González et al, 2014;Gonzalez-Navarro et al, 2016;Terrile et al, 2017). Interestingly, the yield-related traits not only exhibited large variation across all experiments and locations but also displayed that genetic effect was consistently larger than genotype ´ environment interaction, resulting in moderate to high heritability levels.…”

“…In addition, some phenotypic studies have reported a negative relationship between FE and yield-related traits such as spike weight at anthesis (SWA) or grain weight (Gaju et al, 2009;Ferrante et al, 2012;Lázaro and Abbate, 2012). In contrast, González et al (2011González et al ( , 2014 found no meaningful relationship between the mentioned traits. The possible presence of trade-offs between FE and SWA or grain weight per spike (GWS), depending on the nature of the relationship, might make improvements in FE either relevant or of little value to improve yield potential (Gonzalez-Navarro et al, 2016).…”

Wheat grain number: Identification of favourable physiological traits in an elite doubled-haploid population

“…Thus, the reduction in average grain weight might be simply the reflection of an increased proportion of distal grains (Miralles and Slafer, 1995), representing a non-competitive partial compensation between fruiting efficiency and final grain weight. A recent study with a large set of Argentinean high-yielding cultivars differing in fruiting efficiency did not report a negative relationship between this trait and potential grain weight, reinforcing the idea that the fruiting efficiency could be increased to improve GN in elite wheat cultivars (González et al, 2014).…”

A reductionist approach to dissecting grain weight and yield in wheat

“…grain cell elongation, grain filling rate). While grain filling is most commonly considered to be sink‐limited, events pre‐anthesis are most commonly considered to be source‐limited (Slafer and Savin ; Borrás et al ; Slafer et al ; Miralles and Slafer ; González et al ). Therefore, this suggests that it is important to consider interactions between source and sink tissues and understand how they can be simultaneously improved.…”