Abstract: In this paper, the biological traits, physiological parameters, and enzyme activities related to N assimilation and metabolism of wheat varieties with different nitrogen (N) efficiency were studied under low and high N supply. The results showed that under low N supply, the dry mass of root, leaf, and stem as well as the accumulated N amount in plant were in the order of high N efficiency variety>mid N efficiency variety>low N efficiency variety. The variety with high N uptake efficiency (Ji 97-6360) under low N supply had the highest root active absorption area and TTC-reductive activity and the highest leaf nitrate reductase activity and NO₃^-content, while the variety with high N physiological efficiency (Shixin 5418) had higher nitrite reductase and glutamine synthetase activities but lower NO₃^- content and NR activity in its leaf. There was a significant positive correlation between nitrogen use efficiency (NUE) and nitrogen uptake index (NUI) under low N supply. The biological traits, physiological parameters, and enzyme activities related to nitrogen assimilation and metabolism of test wheat varieties were not always the same under high and low N supply.

Key words: half-sib family, resistance to disease and insect, variance., fruiting, Pinus koraiensis, growth