【摘要】 在盆栽条件下,研究了喷施KNO3对新高梨实生苗硝酸还原酶活性(NRA)和氮素积累的影响。结果表明,最高NRA(386.28nmolNO2-/g·hFW)出现在喷施10mmol/LKNO38h后。叶片和根系中(+NO3-)NRA均显著地高于(-NO3-)NRA,其中(+NO3-)NRA与KNO3喷施浓度不存在任何相关性,但(-NO3-)NRA与KNO3喷施浓度呈显著正相关。NRA在茎上各叶位中的分布由顶部向基部逐渐减少。叶片中全氮和还原氮含量随KNO3喷施浓度的增加而增加,但硝态氮含量相对稳定;根系中氮素含量变化与KNO3喷施浓度相关性不明显。叶片和根系中(+NO3-)NRA与氮素含量变化无任何关系;叶片中(-NO3-)NRA与全氮和还原氮含量呈正相关,而根系中(-NO3-)NRA与氮素含量变化不存在任何相关性。因此认为硝酸盐还原在叶片和根系中可能存在不同的酶调控机制。更多还原

【Abstract】 Effects of KNO3 spray on nitrate reductase activity (NRA) and nitrogen accumulation were studied in Pyrus pyrifolia cv. Niitaka seedlings grown in pots. A total of 386.28 nmoles NO2-/h/g FW NRA appeared after 8 h spraying with 10 mmol/L KNO3. The (+NO3-) NRA was significantly higher than the (-NO3-) NRA in leaves and roots. There was no any correlation between the (+NO3-) NRA and spraying concentrations of KNO3 in leaves and roots however a significant positive correlation was found between the (-NO3-) NRA and spraying concentrations of KNO3 in leaves and roots. The NRA decreased accordingly from the top to the base of the stem. Increasing concentrations of KNO3 increased the concentrations of total and reduced nitrogen in leaves but nitrate nitrogen remained relatively stable however there were no significant changes of nitrogen contents in roots after spraying KNO3. No any correlation was found between the (+NO3-) NRA and change of nitrogen contents in leaves and roots; there was a positive correlation between the (-NO3-) NRA and total and reduced nitrogen contents in leaves however, no any correlation was found between the (-NO3-) NRA and changes of nitrogen contents in roots. It is suggested that the enzyme system regulating nitrate reduction in leaf may be different from those in root.更多还原