Floodwater oxygen content, ethylene production and lenticel hypertrophy in flooded mango (Mangifera indica L.) trees.
Larson K. D., Schaffer B., Davies F. S.
Author Affiliation: Tropical Research and Education Center, University of Florida, Homestead, FL 33031, USA.
Journal of Experimental Botany 44 : 665-671
Abstract : A system with 4 flooding chambers was developed to test the effects of floodwater O2 concentration on ethylene evolution and stem lenticel hypertrophy, and the effects of exogenous ethylene on stem lenticel hypertrophy in potted, 1.5- to 2-year-old mango cv. Peach trees. Dissolved O2 concentrations of 1-7 × 10-9 m³/m³ generally resulted in hypertrophy of stem lenticels within approx. 6 days of flooding, whereas O2 concentrations of 13-15 × 10-9 m³/m³ delayed hypertrophy until approx. day 9. After 14 days of flooding, there were more than twice the number of hypertrophied lenticels per tree with floodwater O2 concentrations of 1-7 × 10-9 m³/m³ than with O2 concentrations of 15 × 10-9 m³/m³. Ethylene evolution from stem tissue immediately above the floodline increased 4- to 8-fold from the start of treatment in trees exposed to floodwater O2 concentrations of 1-2 × 10-9 m³/m³, and 2-fold for trees exposed to floodwater O2 concentrations of 6-7 × 10-9 m³/m³, but remained constant with floodwater O2 concentrations of 13-15 × 10-9 m³/m³. Plants maintained in highly oxygenated floodwater (13-15 × 10-9 m³/m³) and given exogenous ethylene (2 × 10-3 m³/m³ for 10 s at 24-h intervals) developed many hypertrophied lenticels, whereas plants in highly oxygenated water and not given ethylene developed fewer or no hypertrophied lenticels. The data suggest that ethylene plays a role in promoting stem lenticel hypertrophy in flooded mango trees, and that floodwater dissolved oxygen concentration can regulate stem lenticel hypertrophy and ethylene evolution.