【摘要】 通过Hoagland营养液水培玉米 ,定量研究了供S水平对玉米根系活性和植株S、N代谢特性的影响 .当玉米缺S时 ,玉米根系活性和叶片硝酸还原酶 (NR)活性显著降低 ,植株冠 /根比增大 ;根系与地上部对S、N的吸收均减少 ,S在根系和新生叶中分配相对减少、在衰老叶和茎鞘中分配相对增多 ;N在根系中分配增多 ,新生叶和完全展开叶中分配相对减少 ;植株蛋白质、蛋白氮、蛋白硫、无机硫的含量均显著降低 ,非蛋白氮比率增多 ,无机硫占总S的比率变小 ,全N/全S比增大 ;蛋白质中的N/S比在地上部无显著变化 ,而在根系中显著增大 ;根系对S缺乏的反应更为敏感 .研究表明 ,缺S植株蛋白质含量与NR活性之间呈极显著正相关 ;S的缺乏或过量均影响玉米的N、S代谢 ;以根系作为S素营养诊断器官 ,以N/S比或无机S/全S比作为诊断指标较灵敏 ,正常条件下其数值分别为 10 .7和 0 .3 0 2 .更多还原

【Abstract】 The effects of different sulfate supply level on N and S metabolism and on root vigor of corn were quantitatively studied with Hoagland solution under greenhouse conditions.The results showed that in S deficient solution,root vigor and leaf nitrate reductase (NR) activity significantly rdduced,top root ratio (T/R) increased,and S and N accumulation in tops and roots decreased.The partition of S decreased in roots and incompletely expanded leaves,but increased in senescent leaves and sheaths stems ;while the partition of N increased in roots,but decreased in incompletely and fully expanded leaves.The content of protein,protein N,protein S,and sulfate S significantly reduced, percentage of non protein N increased,inorganic S/total S ratio decreased,and total N/total S ratio increased.The protein N/protein S ratio in tops had no observable changes.but increased significantly in roots,showing that root was a sensitive organ to S deficiency.There was a close relatioinship between protein content and NR activity in S deficiency.Deficient or excessive S supply limited N and S metabolism of corn plant.N/S or inorganic S/total S ratio in roots was a sensitive index to indicate the deficiency of S supply,which was 10.7 or 0.302 under normal condition,respectively.更多还原