氮素水平对花生氮素代谢及相关酶活性的影响

 在大田高产条件下研究了氮素水平对花生(Arachis hypogaea)可溶性蛋白质、游离氨基酸含量及氮代谢相关酶活性的影响, 结果表明, 适当提高氮素水平既能增加花生各器官中可溶性蛋白质和游离氨基酸的含量, 又能提高硝酸还原酶、谷氨酰胺合成酶和谷氨酸脱氢酶等氮素同化酶的活性, 使其达到同步增加; 氮素水平过高虽能提高硝酸还原酶和籽仁蛋白质含量, 但谷氨酰胺合成酶(GS)和谷氨酸脱氢酶(GDH)的活性下降; N素施肥水平不改变花生植株各器官中可溶性蛋白质、游离氨基酸含量以及硝酸还原酶(NR)、谷氨酰胺合成酶、谷氨酸脱氢酶活性的变化趋势, 但适量施N (A2和A3处理)使花生各营养器官中GS、GDH活性提高; 氮素水平对花生各叶片和籽仁中GS、GDH活性的高低影响较大, 但对茎和根中GDH活性大小的影响较小。

EFFECTS OF NITROGEN LEVEL ON NITROGEN METABOLISM AND CORRELATING ENZYME ACTIVITY IN PEANUT

Aims Nitrogen is very important for improving the yield and quality of peanut. Nitrate reductase (NR), glutamine synthetase (GS) and glutamate dehydrogenase (GDH) are the main enzymes of nitrogen metabolism that would be affected by nitrogen level. Our objective was to study the effects of nitrogen level on soluble protein content, free amino acid content and correlating enzyme activities of nitrogen metabolism in peanut. Methods We carried out a field experiment of two cultivars under four nitrogen levels (0, 45, 90 and 180 N kg•hm^–2) and investigated the soluble protein content and free amino acid content in leaf, stem, root and pod of peanut, as well as the activities of the nitrate reductase (NR), glutamine synthetase (GS) and glutamate dehydrogenase (GDH) in these organs. Important findings With the nitrogen application, the soluble protein content and free amino acid content were increased, and the activities of the nitrate reductase (NR), glutamine synthetase (GS) and glutamate dehydrogenase (GDH) also increased. When excessive nitrogen was used, the NR activity and kernel protein content were increased, while the activities of GS and GDH were decreased. Soluble protein content, free amino acid content, NR, GS and GDH along with the growth periods were not affected by nitrogen level, but with suitable nitrogen the activities of NR and GS in different organs could be increased. Also, nitrogen level affected GDH activities in leaf and kernel, with lower effect on the GDH activities in stalk and root. In conclusion, nitrogen level could affect the correlating enzyme activities of nitrogen metabolism in peanut, which resulted in changes of soluble protein content and free amino acid content in organs. The best nitrogen level for peanut was 90 N kg•hm^–2.