Affacts Of Nitrogen On Root Respiration Of Hydroponic Fraxinus Mandshurica Seedling

Root respiration is an energy source for plant root life, which is affected by environmental factors. Being one of the macro elements in plants, nitrogen has a close connection of forest root respiration.In order to study the regulation mechanism of nitrogen on root respiration, solution culture experiments were carried out to study Fraxinus mandshurica seedling treated with various nitrogen levels and nitrogen forms. Meanwhile, rate of CO2 efflux (respiration) on intact roots were measured using a Li-7000 system. And root nitrogen contents, root soluble protein, the key enzymes of nitrogen, carbonhydrate contents were determined. Results as following:There is a certain promotion on the development of root under the treatment of ammonium nutrition; root respiration has a certain seasonal change, and various nitrogen levels have a different effect on root respiration; under the stress of ammonium nutrition, root respiration was more sensitive to environment temperature; the difference of Q10 was not significant (P>0.05) between different treatments; the more nitrogen in the medium, the more accumulation of total N, there is a significant positive correlation between root respiration and the amount of root total N; with increasing of nitrate concentration, root respiration intends to increase; various organ has different sensitivity to the supply of nitrogen, the presence of ammonium nitrogen in medium may influence the absorption of nitrate, which affect the accumulation of soluble protein in plants; the activity of NR increased gradually with the increase of nitrogen concentration, but the activity of GS decreased, the solubility sugar including of glucose, fructose, sucrose of various organ expressed the phenomenon of enhanced ammonium, there was a positive correlation between root respiration of solubility sugar and starch.