甘氨酸浓度对普通白菜幼苗生长及氮代谢关键酶活性的影响

摘要

A hydroponic experiment was conducted to study the effects of different glycine(Gly) concentrations on bakchoi〔Brassica campestirs L. spp.chinensis(L.)Makino var.communis Tsen et Lee〕seedling growth and nitrogen metabolism.The differences of dry matter,total N content,total carbon content and key enzyme activities involved in nitrogen metabolism in 2 pakchoi cultivars(‘Huawang’and‘Wuyueman’) and under 4 Gly concentration(0,2.5,5.0,10.0,20.0 mmol·L-1)were compared.The results indicated that the dry matter,total N content,total carbon content and key enzyme activities involved in nitrogen metabolism first increased then decreased with the increase of Gly concentration.Under 2.5-10.0 mmol·L-1Gly treatment,the dry matters,total N contents,total carbon contents,the activities of glutamine synthetase and glutamate synthase, and root nitrate reductase,root glutamic-pyruvate transaminase,root glutamic oxalo-acetic transaminase of the 2 pakchoi cultivars were generally significantly higher than that of the contrast.Under 20.0 mmol·L-1Gly treatment,the dry matters,total contents of N and C and the activities of most enzymes for both cultivars showed no significant difference with those in the contrast,while the dry matter,total N and C content of‘Wuyueman’were lower than that of the contrast.These results clearly demonstrates that suitable Gly concentration can promote the accumulation of N and C and promote pakchoi growth with relatively greater activities of nitrate reductase,glutamic-pyruvate transaminase,glutamic oxalo-acetic transaminase in roots and GS-GOGAT cycle in both shoots and roots.%为了探讨不同浓度甘氨酸态氮对普通白菜幼苗生长和氮代谢的影响，在水培条件下比较了2个普通白菜品种（华王和五月慢）4个甘氨酸（Gly）浓度水平下（0、2.5、5.0、10.0、20.0 mmol·L-1）全株干质量、总氮含量、总碳含量及氮代谢关键酶活性的差异。结果表明，2个普通白菜品种幼苗干质量、总氮含量、总碳含量及氮代谢关键酶活性均随着甘氨酸浓度的增加呈先上升后降低的趋势；2.5～10.0 mmol·L-1处理下2个普通白菜品种幼苗干质量、总氮含量、总碳含量、谷氨酰胺合成酶活性、谷氨酸合成酶活性及根系硝酸还原酶活性、根系谷草转氨酶活性、根系谷丙转氨酶活性大多显著高于对照；20.0 mmol·L-1处理下2个普通白菜品种幼苗干质量、总碳含量、总氮含量及大部分酶活性基本与对照差异不显著，其中五月慢幼苗干质量、地上部总氮含量、地上部和根系总氮含量显著低于对照。综上，适宜浓度的甘氨酸态氮处理下植株较高的GS、GOGA活性及根系NR、GOT、GPT活性有利于普通白菜对甘氨酸的同化利用，从而促进普通白菜的生长和碳氮积累。