A significant part of wheat total biomass pre and post-anthesis is represented by soluble dry-matter-referred as water-soluble carbohydrates (WSC), accounting for up to 30% of overall biomass at anthesis. The concentration of these sugars shows wide variation for storage and remobilization to grains, even among elite lines. Direct contribution to yield under yield potential environments is estimated to be on average 15% which is significant, but the contribution rises, for example when the crop experiences a warm or dry finish to the cycle. Considering the magnitude of biomass investment in WSC and diversity among elite lines, we investigated the associations between stem and spike WSC and fertility related traits under optimal conditions, aiming to understand their potential exploitation in pre-breeding for yield potential. Four panels were studied in the field, CIMCOG in 2012 and 2013, HIBAP I in 2016 and 2017, HIBAP II in 2018 and 2019 and HIBAP III in 2020 and 2021, accounting for over 350 elite, synthetic derived and landrace derived lines. There was wide variation in stem WSC concentration across all panels, showing acceptable broad sense heritability values (~0.7). There were positive associations between stem and spike WSC concentration and grains per m2 and harvest index, suggesting an important role of WSC not only for grain filling but also for grain set. The mechanisms underpinning these associations are discussed. Although seasonal effects were observed across years in the HIBAP panels, site regressions using common lines showed stable rankings, underscoring the potential for the identification of lines with high WSC concentration to be selected as parental material for pre-breeding. Penalties for grain yield in the context of breeding for high WSC concentration are discussed.