Cytokinins: The key to differences in patterns of canopy senescence in Stay-Green and Fast Dry-Down sunflower hybrids

STRIKER GG; MANGIERI MA; CHIMENTI CA; HALL AJ

Edirne

Congreso; 19th International Sunflower Conference; 2016

Committee of the 19th International Sunflower Conference

This study documents the dynamics of cytokinin levels in leaves and their association with root functionality and leaf senescence in irrigated crops of two sunflower hybrids with different patterns of leaf senescence (stay-green[SG] and fast dry-down[FDD]) grown in two years. During grain filling-phase, green leaf area index (GLAI) and live root length density (LRLD) were followed, together with total chlorophyll content (CT), fluorescence (Fv/Fm), net photosynthesis (FN) and trans-zeatin (ZT) levels in leaves of positions H17, H20, H22 and H24. In all positions, hybrids and years the beginning of leaf senescence was associated with decreases in CT (first variable to decrease), followed by falls in Fv/Fm and FN. Differences (p