Root Aerenchyma Development in Spartina Patens in Response to Flooding

Root aerenchyma, developed in response to flooding, was measured as specific gravity in previously existing (old) and newly developed (new) roots of Spartina patens in a 25-day greenhouse experiment. Root specific gravity was related to porosity (fractional volume of aerenchyma): porosity = 1.026 - 0.969 x specific gravity, over a wide range of specific gravities (0.5 to 0.9). The specific gravity of flooded roots (new and old) decreased from 0.78 to 0.58 between day 5 and 25, while the specific gravity of old roots that remained drained did not change. After 5 days growth, newly produced roots were found to have less aerenchyma than their older counterparts, but after 25 days the specific gravity of new roots equaled that of old roots. In addition, flooding increased mortality of preexisting roots and inhibited growth of new roots