In-Field Assessment of Foliar Cytokinin Timing and Dosage Effects on Morphological Traits, Photosynthesis, Yield and Quality in Common Wheat

The increasing frequency of heat waves and drought during wheat ripening undermines yield potential and grain quality by accelerating plant senescence. This study investigated the effects of late foliar cytokinin (6-benzyladenine, 6-BA) application timing and dosage on leaf greenness, photosynthesis, yield, and grain quality in openfield wheat cultivation in NE Italy. Four application timings were evaluated: at flowering (T1), and at 10 (T2), 20 (T3), and 30 (T4) days after flowering, and two double applications (T1+T3; T2+T3), at three 6-BA doses (25, 50 and 150 g ha􀀀 1) compared with untreated controls (C). T1 application significantly prolonged canopy greenness (p ≤ 0.05), while increases in CO2 assimilation (+15 %) and yield (+6 %) were non-significant. Grain protein content improved significantly, and gluten composition shifted toward a higher glutenins/gliadins ratio. Later applications, especially T3, significantly increased leaf chlorophyll content, the glutenins/gliadins ratio, and lowmolecular- weight glutenins, whereas double applications mainly enhanced root development in the upper soil profile (+20 to +33 %) without yield benefits. T2 and T4 were largely ineffective for canopy greenness, but showed selective positive effects on protein or root traits. Overall, yield responses remained non-significant, but cytokinin effects were stage-dependent, with treatments at flowering providing the most consistent benefits at doses ≥50 g ha􀀀 1. Taken together, these findings support a dual-role model of cytokinin action: early 6-BA sprays delay senescence and enhance N remobilization, while later sprays alter gluten composition, highlighting the potential of cytokinin treatments to improve wheat resilience and quality under field conditions; validation across environments and genotypes is still required.