To meet global wheat demands it is important to expand our current understanding of how physiological traits are associated with genetic gains and to identify phenomic and genomic approaches to improve yield potential (Aisawi et al., 2015). Yield is directly related to both biological yield (above-ground dry-matter per unit area; AGDM) and harvest index (grain yield/AGDM; HI), but in recent years the rate of genetic progress in HI has not increased; indeed, there is evidence for decreases in CIMMYT spring wheat modern cultivars as a result of a trade-off with increasing biomass (Aisawi et al., 2015). Therefore, it is important to identify new avenues for optimal dry matter (DM) partitioning of assimilates in order to improve grain sink strength – grain number – and HI in high biomass backgrounds as well as further identify genetic markers for these traits for application in marker-assisted selection. A summary of the main DM partitioning data collected during 2015-16 in the CIMMYT high biomass spring wheat panel HiBAP (High Biomass Association Panel, 150 genotypes) is presented and discussed. The general aim is to identify combinations of novel DM partitioning traits to increase HI. Results showed a strong association amongst genotypes between grain yield and AGDM (R 2=0.49, P< 0.001), a trade-off between AGDM and HI (R 2=0.23, P< 0.001) and an association between enhanced HI and reduced length of internode 3 (peduncle -2) (P< 0.05) at anthesis (GS65 +7d).
Physiological traits to increase grain partitioning in high biomass cultivars in wheat