不同小白菜器官对氮素形态响应的生理差异

Response of different varieties of Chinese cabbage to nitrogen forms

通过水培试验研究了不同形态氮素比例对 4个不结球小白菜品种单株生物量 ,叶片、叶柄及根系与整株的比例 ,叶片叶色值 (SPAD值 )以及不同器官硝酸盐含量的影响。结果表明 :在NH+4 N/NO-3 N为 2 5∶75时小白菜的单株生物量最大 ;随着NH+4 N/NO-3 N的变小 ,根重 /株重及叶重 /株重先减后增 ,而叶柄重 /株重则与前两者的变化规律完全相反 ;叶片SPAD值与营养液中的NH+4 N/NO-3 N的相关性达 0 9以上 ;叶片、叶柄及根的硝酸盐含量均随着营养液中硝态氮比例的增大而增加 ,以叶柄的硝酸盐含量最高 。

Four cultivars of Chinese cabbage were grown in nutrient solution with five different NH + 4 N/NO - 3 N ratios,i e., 100∶ 0,75∶25,50∶50,25∶75 and 0∶100,to study the effects of different NH + 4 N/NO - 3 N ratios on biomass of different organs in total plant,SPAD readings and nitrate content in different organs of Chinese cabbage.The result showed that the highest biomass was obtained when the NH + 4 N/NO - 3 N ratio was 25∶75.The correlation between SPAD readings and NH + 4 N/NO - 3 N ratio in the solution was over 0 9.With the decreasing NH + 4 N/NO - 3 N ratio,the percentages of root and leaf in total plant(fresh weight)were both decreased and thereafter increased,while the percentage of petiole in total plant(fresh weight)was totally different from the former two.All nitrate contents in the root,petiole and leaf increased as the fraction of nitrate in the solution increased and nitrate content in petiole was the highest but that in root was the lowest.