冬枣硝酸还原酶特性研究

Study on Nitrate Reductase of Winter Jujube(Ziziphus jujuba var.inermis)

在盆栽条件下,以沾化冬枣为试材,研究植株不同器官、不同时期NR活性的变化动态以及不同形态氮素对NR活性的影响。结果表明:叶片是冬枣NO3-还原的主要部位,NR活性以新生叶片中最高,其次为中部叶和基部叶;根系中NR活性以细根中较高,但明显低于叶片,而新生吸收根中几乎检测不到。日变化表明NR活性呈单峰曲线,以上午11:00左右最高。从NR活性的季节变化看:叶片NR活性先增加后下降,以夏季8月中旬较高;根系NR活性在6月、8月初和10月出现3次高峰。叶片涂抹不同浓度与不同形态氮素对NR活性的影响存在差异。涂抹40mmol.L-1KNO34h后,NR活性达到高峰,涂抹低浓度KNO3(<80mmol.L-1)可以显著提高NR活性,而高浓度KNO3(>80mmol.L-1)处理时NR活性不再升高,涂抹尿素也可提高NR活性,Glu和Gln对NR活性影响不大,Gly降低了NR活性。土壤施肥对NR的影响表明:追施尿素可以维持叶片较高的NR活性水平,提高叶片对NO3-的同化能力。

Experiments were conducted with potted jujube to study the changing of NR activity in different organs and periods as well as the effect of different nitrogen forms on NR activity. The result showed： leaf was the main organ which assimilated NO3^- The new-leaf has the highest NR activity, then was the mid-leaf. The activity of down-leaf was the lowest. NR activity of fine-root was higher than other roots but lower than leaves, the activity of absorption roots could not be observed. Further, the diurnal variation of NR activity in vivo showed a peak curve and maximal NR activity appeared at about 11：00 or so. The change of seasons showed NR activity in leaves was higher in August comparing with other seasons and NR activity of roots appeared three peak in Jun, Aug and Oct. In addition, the effect of different nitrogen forms on NR activity indicated a peak appeared after 4 h daubing leaves with 40 mmol·L^-1 KNO3. NR activity in vivo could be raised by lower concentration of KNO3 （ 〈 80 mmol·L^-1 ） and be increased no more with higner concentration of KNO3 （ 〉 80 mmol·L^-1 ）. NR activity could also be improved by daubing urea. In addition, NR activity was not significant effected after daubing Glu or Gin, however, was remarkablely decreased by Gly. Fertilization in soil showed urea could maintain the higher NR activity in leaves and increased the ability of assimilation NO3^- .