Oxygen Requirements for Germination and Growth of Flood-Susceptible and Flood-Tolerant Corn Lines
This study determined the oxygen requirement for germination and growth of flood-susceptible and flood-tolerant corn (Zea mays L.) lines. Such information is necessary for the establishment of more efficient drainage design criteria. In addition, the role of adenylate energy charge (AEC) in corn tolerance to anoxia was also evaluated. Two seed lots of five corn inbreds and five corn hybrids were germinated at constant (0, 2.5, 4.8, 10.5, 14.5, and 20.9 kPa) or fluctuating (daily fluctuations between either 0 and 20.9 kPa, or 2.5 and 14.5 kPa) O2. Percent seed germination, the number of adventitious roots, and shoot and root dry weight were determined after 96 h of treatment. The adenylatenergy charge (AEC) of inbred seeds germinated under constant O2 concentration was assessed by luciferin-luciferase assay. The results indicated that flood-tolerant corn lines could germinate at lower O5 concentrations than flood-susceptible lines. The fluctuation between high and low O2 levels proved to be more damaging to germination and seedling growth than the compatible constant low O2 treatment. Corn plants apparently can tolerate prolonged anaerobic stress better than alternating periods of stress and nonstress. The germinated seeds from both flood-tolerant and flood-susceptible lines possessed similar adenylate energy charge (0.70 to 0.84). At low O2 concentrations, the number of seeds which possessed sufficient energy charge for germination was higher in the flood-tolerant than in the flood-susceptible lines. The positive correlation of adenylate energy charge and flooding tolerance indicated that flooding tolerance in corn is probably related to its ability to produce, or to conserve, metabolic energy under stress.
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