摘要
The effects of ammonium (NH4+-N) and nitrate (NO3- - N) were examined on Fe fractions and FeCN (ferricyanide) reductase activity in intact root tips (0-3 cm) of young maize (Zea mays L. cv. Lenz) in solution culture by using short-term experiment under controlled Fe deficiency conditions (containing high HCO3- concentration in pre-culture solution). The results showed that Fe(Ⅱ) concentrations in root tip apoplast of maize were only 20-40 nmol/g FW which accounted for 7%-13% of total Fe. Most of Fe in root tips existed as Fe(Ⅲ) compounds. Imposition of the roots to NH4+ - N or NO3- - N for 60 min led to an increase of Fe(Ⅱ) in root tip apoplast. NH4+ - N led to an increased concentration of Fe(Ⅱ) and exchangeable Fe (Fe(Ⅱ) and Fe (Ⅲ)) in root tips, while NO3- - N increased FeCN reductase activity. The relationship between pH and Fe fractions, FeCN reductase activity was also discussed.
The effects of ammonium (NH 4 + -N) and nitrate (NO 3 ? -N) were examined on Fe fractions and FeCN (ferricyanide) reductase activity in intact root tips (0–3 cm) of young maize (Zea mays L. cv. Lenz) in solution culture by using short-term experiment under controlled Fe deficiency conditions (containing high HCO 3 ? concentration in preculture solution). The results showed that Fe(II) concentrations in root tip apoplast of maize were only 20–40 nmol/g FW which accounted for 7%–13% of total Fe. Most of Fe in root tips existed as Fe(III) compounds. Imposition of the roots to NH 4 ±N or NO 3 ?N for 60 min led to an increase of Fe(II) in root tip apoplast. NH 4 ±N led to an increased concentration of Fe(II) and exchangeable Fe (Fe(II) and Fe (III)) in root tips, while NO 3 ? -N increased FeCN reductase activity. The relationship between pH and Fe fractions, FeCN reductase activity was also discussed.
基金
This work was supported by the National Natural Science Foundation of China (Grant Nos. 30000103 and 39870480)
the National Key Basic Research Special Funds (Grant No. G1999011707)
by the Deutsche Forschungsgemeinschaft (DFG) for a personal grant on th