Marine and fungal biostimulants (DPI4913 and AF086 Extracts) improve grain yield, plant nitrogen absorption and allocation to ear in durum wheat plants

International audience; Durum wheat culture requires a high fertilization rate to achieve sufficient protein concentration for semolina and pasta quality, contributing to losses through atmosphere and water. Optimizing plant capacity to use N could help improve its agroenvironmental balance Our objective was to study the impact of the marine extract DPI4913 and the fungal extract AF086 on growth, N absorption and fluxes in durum wheat.Three experiments were conducted in France: under standard N 25 fertilization in a first field (Carbonne, 43.333328 N, 1.33333 E), under varying N supply in a second field (Mervilla, 43.503451 N, 1.472316 E) and under varying water conditions in greenhouse (Toulouse, 43.527272 N, 1.501492 E). Various 15N labelling experiments were performed at flag leaf fully emerged stage to follow N fluxes until maturity. In Carbonne, 15NO3- and 15NH4+ were injected in the soil to investigate the effect of biostimulants on allocation to grains of soil mineral N. In greenhouse, some plants were 15NH4+ labelled on the flag-leaf to follow N remobilization. For other plants, flag-leaf was removed at flag-leaf fully emerged stage to characterize flag-leaf implication in N translocation to grains. Flag leaf senescence was studied estimating leaf chlorophyll concentration with the SPAD-502 meter. Under standard N conditions, biostimulants increased mean grain yield in the field (+1.8 % for DPI4913 and 4.0 % for AF086 in Carbonne; +5.5 % for DPI4913 and +3.9 % for AF086 in Mervilla; not significant). In greenhouse, under water standard conditions, biostimulants increased grain yield (+19.7% for DPI4913, +19.3 % for AF086), total N in plant and in ear (respectively +28.9 % and +44.6 % for DPI4913, +23.3 % and +32.7 % for AF086) and proportion of N in the ear (68.7 % for CONTROL, 77.1 % for DPI4913, 74.2 % for AF086). Biostimulants had no effect under N and water stress conditions. In the field, DPI4913 increased soil mineral N accumulated in grains at maturity (15N labelling). In greenhouse, flag leaf N was very mobile (15N resorption of 98.2 %). Biostimulants increased the proportion of 15N applied to the flag leaf recovered in grains (40.9 % for Control, 52.5 % for DPI4913, 47.2 % for AF086, p-value=0.09) and accelerated leaf senescence (SPAD-measurements). Flag leaf key-role in grain filling processes was revealed by the fact that flag leaf ablation decreased N amount in grains more than flag leaf N content at the time of ablation (respectively - 5.9 mg and - 2.7 mg). The increase in N remobilization from flag leaf represented 4.3 % of the supplementary amount of N found in grains for plants treated with DPI4913 and 0.6 % with AF086. Biostimulants mainly increased mineral N root uptake rather than remobilization. In conclusion, it is suggested that DPI4913 and to a lesser extent AF086 – which promote plant growth, N uptake and remobilization – could be used in standard N and water conditions to optimize durum wheat N fertilization.