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Studies on the Assimilation of Nitrate-N and its Translocation within Plants, Fruit and Vegetables.

植物、水果和蔬菜中硝酸盐氮的同化及其转运的研究。

基本信息

批准号：
63560024
负责人：
TACHIBANA Shoji
金额：
$ 1.41万
依托单位：
Mie University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63560024/
关键词：
Cucumber Diurnal change Nitrate reductase Nitrate reduction Root Translocation 果実硝酸還元

项目摘要

Nitrate reduction takes place in all parts of plants but at different rates. It is known that nitrate-N hardly retranslocate within plants through phloem. Therefore, the organs low in nitrate reducive activity may depend on other organs high in the activity for reduced-N. This research work was conducted to see the relative contribution leaves, roots and fruits to the whole plant nitrate reduction, using cucumber as plant materials. The nitrate reductase activity of roots was much lower than that of leaves. But, the relative contribution of roots to the total nitrate reduction varied between the day and night, mainly due to the daily fluctuation of nitrate reductase activity in leaves.Retranslocation of reduced-N from leaves to roots took place at about the same rate in the day and night. When N was omitted in the rooting medium, roots grew well by utilizing N supplied from leaves. However, the amount of retranslocation of it was small when adequate N was present in the medium. It was concluded that cucumber roots normally acquire most of reduced-N by their own nitrate reduction.Nitrate reductase activity of cucumber fruits was low, compared with the activity in leaves, though peels of fruits possesed high activity comparable to the activity in leaves. Thus, cucumber fruits is able to reduce nitrate-N for their use in growth. On the other hand, it was found that cooling the peduncle and the foliar spray of agent which inhibits glutamine synthetese activity decreased greatly the fruit growth as well as the accumulation of N absorbed by the roots. This result indicates that growth of cucumber fruits depend, at least to some extent, on the supply of reduced-N by leaves. If this is the case, then growth of cucumber fruits can be influenced by the source-sink relationships to reduced-N between leaves and fruits.

硝酸盐还原发生在植物的所有部位，但速率不同。硝态氮在植物体内几乎不通过韧皮部再转运。因此，硝酸盐还原活性低的器官可能依赖于其他还原氮活性高的器官。以黄瓜为试材，研究了叶片、根系和果实对全株硝酸盐还原的相对贡献。根的硝酸还原酶活性远低于叶。但根系对硝酸盐还原总量的相对贡献在昼夜之间存在差异，主要是由于叶片硝酸还原酶活性的日变化，还原态氮从叶片向根系的再转运速率在昼夜之间基本相同。当生根培养基中不加氮时，根能充分利用叶片提供的氮素生长。但在氮素充足的情况下，其转运量较小。结果表明，黄瓜根系通过自身的硝酸还原作用吸收还原态氮，果实硝酸还原酶活性较低，果皮硝酸还原酶活性较高，与叶片相当。因此，黄瓜果实能够减少硝态氮用于生长。另一方面，冷却果梗和叶面喷施谷氨酰胺合成酶抑制剂，则大大降低了果实的生长和根系吸收氮的积累。这一结果表明，黄瓜果实的生长至少在一定程度上依赖于叶片还原态氮的供应。如果是这样的话，那么黄瓜果实的生长可能会受到叶片和果实之间的源库关系的影响。