冬枣对不同形态氮素的吸收与利用

以2年生盆栽鲁北冬枣为试材，研究了其对尿素、甘氨酸（Gly）和谷氨酸（Glu）的吸收利用与响应特性．结果表明：3种形态氮均可被冬枣吸收利用，与尿素相比，氨基酸态氮吸收的量较少．若尿素的吸收量以100％计，则叶片对Gly和Glu的相对吸收量分别为28．88％和11．73％，吸收到的氮素主要分配到叶片和枣头枝中；而根对Gly和Glu的相对吸收量则分别为50．48％和42．72％．冬枣吸收尿素、Gly和Glu后，叶片中的谷草转氨酶（GOT）和谷丙转氨酶（GPT）活性提高，可溶性蛋白质含量增加；但不同形态氮素处理对硝酸还原酶（NR）活性的影响存在差异，尿素可显著提高NR活性，Glu对NR活性影响不大，Gly降低了NR活性．与尿素相比，氨基酸态氮能明显提高冬枣果实的着色个数、着色面积以及果实中可溶性固形物含量．

Absorption and utilization of different applied nitrogen forms by winter jujube

With pot experiment, this paper studied the absorption and utilization of applied urea N, Gly N and Glu N by two years old winter jujube. The results showed that all of the three N forms could be absorbed by the winter jujube, but the absorption rate of Gly N and Glu N was less than that of urea N. Taking the absorption rate of urea N as 100% , the relative absorption rate of Gly N and Glu N by jujube leaves was 28. 88% and 11.73%, respectively, and the absorbed N was mainly allocated to the leaves and neonatal branches. Jujube roots could absorb 50. 48% of Gly N and 42. 72% of Glu N. The transaminase activity and soluble protein content in jujube leaves were increased after the application of these three N forms, but the leaf nitrate reductase activity was enhanced significantly by urea N, decreased by Gly N, and less affected by Glu N. Compared with urea N, amino acid N could significantly increase the number of colored fruits and their colored area, as well as the content of fruit soluble solid matter.