氮素形态和光照强度对烟草生长和H_2O_2清除酶活性的影响

EFFECT OF LIGHT INTENSITY AND NITROGEN FORM ON GROWTH AND ACTIVITIES OF H_2O_2-SCAVENGING ENZYMES IN TOBACCO

氮素形态和光照强度对烟草植株生长和H2O2清除酶活性影响的研究结果表明，在弱光下，氮素形态不影响植株生长，但在强光下，铵态氮明显抑制植株的生长。弱光下供应按态氮叶片叶绿素含量显著地高于供应硝态氮的叶片;而强光下供应铵态氮叶片单位鲜重叶绿素含量反而显著地低于供应硝态氮的叶片。强光下供应按态氮的叶片中MDA含量明显高于供应硝酸盐的叶片，但在弱光下则无明显的差异。供应硝态氮叶片中AsA含量高于供应铵态氮的叶片;但供应铵态氮叶片中DAsA含量高于供应硝态氮叶片，尤其是强光下其差异更大。光照强度的增加明显提高AsA-POD、MDAsA还原酶、DAsA还原酶和GSSG还原酶活性。强光下供应镀态氮叶片中AsA-POD和GSSG还原酶活性明显地高于供应硝态氮的叶片，而MDAsA还原酶活性则相反。弱光下供应铵态氮叶片AsA-POD和MDAsA还原酶活性明显高于供应硝态氮的叶片，而GSSG还原酶活性的差异则不显著。铵态氮不显著提高DAsA还原酶的活性。SOD和CAT活性在各处理之间差异不明显。增加光照强度和供应铵态氮都明显地提高AsA氧化酶活性。

The effects of light intensity and nitrogen form on plant growth and the activities of H2O2-scavenging enzymes in leaves of tobacco were studied. The results showed that the plant growth was not affected by nitrogen form under liw light intensity, but considerably inhibited by ammonium nutrition under high light intensity. The chlorophyll contents of leaves were significantly increased by ammonium nutrition under low light intensity, however, the chlorophyll content per fresh weight was significantly decreased by ammonium nutrition under high light intensity. The MDA content was greatly increased by ammonium nutrition under high light intensity, but not significantly increased under low light intensity. The ascorbate content was considerably increased by increased light intensity, but significantly decreased by ammonium nutrition. The content of dehydroascorbate was greatly promoted by ammonium nutrition, especially under high light intensity.The activities of AsA-POD, MDAsA reductase, DA sA reductase and GSSG reductese were greatly increased by increased light intensity. Under high light intensity the activities of AsA- POD and GSSG reductase were greatly increased by ammonium nutrition, however, the activity of MDASA reductase was considerably inhibited.Under low light intensity the activities of AsA-POD and MDAsA reductase were significantiy increased by ammonium nutrition and the activity of GSSG reductase was not significantly increased. The activities of DASA reductase were increased by ammonium nutrition, but not significantly. There were no significant differences of activities of SOD and CAT among the treatments.