NH_4^+-N部分代替NO_3^--N对番茄生育中后期氮代谢相关酶活性的影响

INFLUENCE OF PARTIAL REPLACEMENT OF NO_3^--N WITH NH_4^+-N IN NUTRIENT SOLUTION ON ENZYME ACTIVITY IN NITROGEN ASSIMILATION OF TOMATO AT DIFFERENT GROWING STAGES

采用砂培实验研究NH4+-N部分代替NO3--N对番茄的影响,结果表明:与全硝处理(100%NO3-)相比较,增铵处理(NH4+∶NO3-=25%∶75%)下番茄鲜果重显著提高;同时叶片内NO3--N含量随增铵而显著降低,叶片与果实内NH4+-N含量及果实的可溶性蛋白含量随增铵而升高;增铵条件抑制了叶片和果实的硝酸还原酶(NR)活性,提高了叶片和果实的磷酸烯醇式丙酮酸羧化酶(PEPcase)活性及叶片谷氨酰胺合成酶(GS)活性,但对果实的谷氨酰胺合成酶(GS)活性影响不大。上述结果表明,NH4+-N部分代替NO3--N可增加番茄产量,提高集约化基地的生产量。

Studies were carried out on influences of replacement of 25 % NO3^- -N with NH4^＋ -N in nutrient solution （ enhanced ammonium nutrition） on tomato growth and activity of such key enzymes in N assimilation and organic acids as nitrate reductase （NR）, glutamine synthetase（GS） and phosphoenolpyruvate carboxylase （PEPcase）in tomato leaves and fruits sampled at different developmental stages. The results showed that the replacement of 25 % NO3^--N with NH4^＋ -N led to a significant increase in fruit fresh weight, NH4^＋ -N content in both leaves and fruits and soluble protein content in fruits, while led to decrease significandy in NO3^--N content in tomato leaves. Meanwhile, significant enhancement of the activity of PEPcase in both leaves and fruits and of GS in leaves were observed but not much change in GS activity in tomato fruits was. NR activity was often observed to decrease dramatically in both fruit and leaves in enhanced ammonium treatment.