The effects of rhizosphere inundation on the growth and physiology of red maple (Acer rubrum L.) seedlings derived from wet and dry sites
Red maple seedlings grown from fruits collected from matched wet and dry sites from three physiographic regions of Virginia were flooded to test whether red maple seedlings derived from wet sites are affected differently by flooding than are seedlings derived from dry sites.
Thirteen weeks of soil inundation on seedling growth found no interactions between flooding and maternal hydrologic condition. However, flooding significantly decreased leaf, stem, and root dry matter accumulation as well as height growth, leaf area growth, root to shoot ratio, mean relative growth rate, net assimilation rate, and mean leaf area ratio.
Thirteen days of rhizosphere inundation as well as six days of recovery on seedling gas exchange determined that flooding significantly decreased photosynthetic rate and leaf conductance. A larger decrease in photosynthetic rate than in leaf conductance resulted in decreased water use efficiency and leaf limitation. There were no interactions between flooding and maternal hydrologic condition.
Fourteen days of flooding decreased root aerobic respiratory capacity and root ethylene evolution, and caused shoot water potential to be less negative. As in the previous studies, no interaction between flooding and maternal hydrologic condition existed.
Although rhizosphere inundation negatively affected the growth and physiology of red maple seedlings, there does not appear to exist any genetic differentiation between wet site and dry site populations affording either of the populations enhanced flood tolerance. Rather, red maple appear to have the species wide phenotypic plasticity to survive flooded conditions.