2.4 Mineral and inorganic phosphorus concentrations
The mineral and Pi concentrations in the root tips (the first 10-mm)
after 2, 6, 24 and 72 h of 5 μM Al treatments were
determined.
Al and P concentrations in whole root of 12 Tibetan wild barley
accessions after 24 h of 5 μM Al treatment were also measured to
determine their correlations with relative root growth under Al stress.
The Al-treated roots were washed with distilled water for three times,
and dried in the oven at 110 °C. Dry sample was digested with
HNO3 using microwave digestion system Microwave 300
(Anton PAAR, Austria). The mineral concentrations were determined using
inductively coupled plasma atomic emission spectrometer (ICP-AES)
(Thermo Jarrel Ash, USA). The Pi concentration was determined according
to Zhou et al (2008) with some modifications. Approximately 50 mg of
fresh root sample was homogenized in 1 ml of 5% (w/v) perchloric acid
and placed on ice for 30 min. After centrifugation at 10,000 g for 10
min at 4 ○C, the supernatant was used for Pi
measurement.