Yield components were only impacted in reproductive plant parts developed after the stress
Yield components were not drastically impacted by the high temperature sequences applied at GS72. Under HS, no effect of temperature was observed on yield of podsL≥5cm, meaning that the seeds from podsL≥5cm experienced a normal filling period. Therefore the impact of the heat sequences on total seed yield was the consequence of a yield reduction in seeds from podsL<5cm, which resulted from reductions in seed number and individual seed weight, even though neither component was significant. Indeed, abortions of young pods during the T-modality exposure and/or failure of pollination in the flowers present during this period might have occurred (Young et al. 2004). Changes in the reproductive strategy might also have reduced the incidence of late flowering (specific to indeterminate species) to the benefit of filling seeds in already developed pods. These observations are consistent with prior studies in pea (another indeterminate growth species) that demonstrated heat-stress modification of seed distribution along the main stem, which led to larger quantities of seeds on the basal parts than on the upper parts where reproductive organs are younger. These results explained the maintenance of seed yield from basal reproductive parts due to a higher allocation rate of carbohydrates and excluded the direct effects of heat stress on developing seeds (Guilioni, Wéry & Lecoeur 2003). The non-significant effect of S on seed yield components, other than the total seed number, indicates that the LS supply in our study satisfied growth rate and yield requirements. Nevertheless, LS conditions impacted a few quality criteria related to nutritional value such as seed S content, SFAs and UFAs (Figure 2), as well as the concentrations of phytohormones involved in stress-induced secondary seed dormancy.