杉木硝酸还原酶活力、氮素贮藏与其生长的关系

Study on the Relationship between Nitrate Reductase Activity, Nitrogen Storage Contents and the Growth of Chinese Fir

以生长速率不同的两类杉木无性系为试材,研究其氮素同化的关键酶——硝酸还原酶(NR)活力、氮素贮藏量与生长的关系。结果表明:①速生无性系1～2年生苗以及3～5年生幼树的NR活力均高于慢生无性系。NR活力随生长过程变化,每年的生长初期NR活力较低,生长盛期活力最高,接近生长停止(封顶)期NR活力明显下降。②在生长期间,速生无性系叶片的总氮含量高于慢生无性系。追施氮肥可明显提高杉木NR活力,增加其总氮含量,并促进幼苗的生长。在杉木生长停止后,速生无性系1年生苗韧皮部的总氮含量、主干和侧枝的硝酸盐含量以及叶片和韧皮部的氨基酸含量都分别比慢生无性系苗高14％、25％和70％以上。③通过对采穗圃18个无性系测定,得知1年生苗叶片的NR活力与定植后5年生幼树的树高呈显著正相关。从而认为,NR活力是决定杉木速生性的重要因素之一。生长速率不同的无性系,对氮素的吸收同化和贮藏积累能力的差异,是NR活力与杉木速生性相关的生理基础。用NR活力作为杉木生长早期预测指标是可行的。

This paper deals with nitrate reductase (NR) activity and nitrogen storage contents (nitrate,amino acid and total nitrogen) in seedlings of Chinese Fir (Cunninghamia lanceolata Hook.) with different growing rates. The results showed that (1)the level of NR activity varied with the growing period. Generally, during the initial growing stage NR activity was low, and the maximum activity was observed at the peak of the growing season. The NR activity in seedlings of the fast growing clone was higher than that in the slow growing clone. NR activity in young seedlings of different age (1,2,3,4,5 years old) was higher in the fast growing clone than that in the slow growing clone. Positive relationship between NR activity in seedling (1-year old) and tree height (5-year-old) was observed. (2) the fast growing clone had higher ability of uptake and assimilation of nitrogen than that of the slow growing clone. Thus, during and after growing stage, the former contained higher contents of nitrate, amino acid and total nitrogen than the later did. Glutamic acid, aspartic acid and histidine contents in leaves and phloem are about 70% of the total amino acid contents.