Mineral nutrition associated with flower color in hydrangea

Abstract

Analysis of blue and pink flowers of Hydrangea macrophylla DC growing in gardens in Los Angeles gave poor differentiation by concentration of Al in them in contrast to the effect reported in literature. Blue flowers usually associated with acid soils contained 510 μg Al/g dry weight while pink flowers usually associated with alkaline soils contained 481 μg/g. Pink flowers contained 322, 18, 1793, 42, 1.1, 0.6 and 4. 7 μg/g respectively of Fe, Mn, Si, Ti, Mo, Cr and Sn. Blue flowers simultaneously contained respectively of the same elements, 146, 27, 622, 22, 0.4, 0.3, and 2.8. Some of these differences may relate to flower color. Hydrangea cuttings grown in a glasshouse in soils of different pH values had blue flowers at soil pH 3.5 and these flowers were higher in Al, Mn, Mg and Si than flowers which were pink or pinkish blue on plants grown at higher soil pH values.

Key words:

• Soil pH
• iron
• aluminum
• silicon
• micronutrients
• flower color