POTASSIUM UPTAKE CHARACTERISTICS OF TWO MAIZE HYBRIDS AND THEIR PARENTS UNDER THE STRESS FROM A LOW AMOUNT OF POTASSIUM

The objective was to study the relationship between maize hybrids and their parents in potassium ion (K+)-uptake characteristics under the stress from a low amount of potassium. Superoxide dismutase (SOD) activity, the malondialdehyde (MDA) content, the potassium utilization index (KUI), root volume, total and active root uptake area, Michaelis-Menten coefficient (Km), and the maximum rate of uptake (Vm) of different maize (Zea mays L.) genotypes were determined. SOD activity and MDA content in the leaves of Si144, Xianyu335 and PH4CV were significantly higher than the control, whereas for Jidan27, Si-287 and PH6WC, no differences were detected. Jidan27 showed a higher KUI than Xianyu335 under 0.1 mM potassium chloride (KCl), but no differences were observed under 3 mM KCl. Jidan27, Si287, and PH6WC had a greater root volume, total and active uptake areas, higher Vm and smaller Km than the other genotypes under 0.1 mM KCl. The differences in the KUI among maize genotypes resulted from variation in the Km ...