不同氮用量对香稻幼苗生长及生理指标的影响OACSTPCD

In order to explore the effects of different nitrogen application amounts on growth and physio-logical indexes of fragrant rice at seedling stage,the experiment was conducted under sand culture conditions with fragrant japonica rice variety Daohuaxiang 2 as test material.Five nitrogen treatments were set as N20(20 mg/L),N30(30 mg/L),N40(40 mg/L),N50(50 mg/L)and N60(60 mg/L),and their effects on growth of fragrant rice seedlings and activities of key enzymes related to nitrogen metabolism and antioxidant enzymes and soluble protein content in leaves were studied.The Z-score comprehensive evaluation was also carried out based on the indicators significantly related to nitrogen level and the morphological indexes.The re-sults showed that with the increase of exogenous nitrogen concentration,the activities of nitrate reductase(NR),nitrite reductase(NIR),glutamine synthetase(GS),glutamate dehydrogenase(GDH)and gluta-mate synthetase(GOGAT)and the soluble protein content increased firstly and then decreased,and all of them were the highest in N50 treatment.With the increase of nitrogen concentration,the activity of superoxide dismutase(SOD)and peroxide dismutase(POD)showed a trend of first decreasing and then increasing with the lowest value in N40 and N30 treatments respectively.Malondialdehyde(MDA)content at low nitrogen lev-el(below 30 mg/L)was significantly higher than that at high nitrogen levels(above 40 mg/L).The compre-hensive evaluation value(∑Zi)of N40,N50 and N60 treatments were positive,and that of N50 treatment was the highest(10.201).In general,40～60 mg/L nitrogen could ensure the normal growth and development of Daohuaxiang 2 seedlings.But below or over 50 mg/L nitrogen inhibited nitrogen metabolism-related enzymes activities,and below 40 mg/L nitrogen significantly increased the accumulation of MDA.It concluded that 50 mg/L nitrogen was the most benefit to the growth and development of Daohuaxiang 2 rice seedlings.