不同耐氮肥烤烟品种质外体NH_4^+浓度差异和有关生理指标分析

Difference of Apoplastic NH_4^+ Concentration in Flue-Cured Tobacco Varieties with Different Tolerance to Nitrogen Nutrition and Assay of the Related Physiological Parameters

【目的】研究不同耐氮肥烤烟品种叶片质外体NH4+浓度差异与耐氮肥性关系,为筛选对氮素适应范围广的烤烟品种提供理论依据。【方法】以耐氮肥的烟草品种中烟90、中耐氮肥的K326和对氮肥敏感的NC89为试验材料,用盆栽法研究它们之间的质外体NH4+浓度差异。【结果】生育后期3个烤烟品种叶片质外体的NH4+浓度均呈现逐步升高的趋势,中烟90的质外体NH4+浓度最大,NC89最小.谷氨酰胺合成酶(GS)活性和总氮含量下降明显,质外体pH值急剧减小,谷氨酸脱氢酶(NADH-GDH)活性缓慢上升,质外体pH始终低于叶片pH;质外体NH4+浓度与GS活性和总氮都呈显著负相关,与GDH活性呈显著正相关。【结论】烤烟品种耐肥性与其生育后期质外体NH4+浓度,GS活性和GDH活性有关,耐肥性强的烤烟品种其质外体NH4+浓度高,GS活性低,GDH活性高,NH4+挥发多。

【Objective】 The objective of this study was to elucidate the relationship between the apoplastic NH4＋ concentration and the nitrogen tolerance of flue-cured tobacco varieties and to provide a theoretical basis for selecting tobacco variety with different tolerance to nitrogen nutrition.【Method】 A pot experiment was carried out to study the difference of apoplastic NH4＋ concentration in three flue-cured tobacco varieties,ZY90（tolerance to nitrogen）,K326（moderate tolerance to nitrogen） and NC89（sensitive to nitrogen）.【Result】 Apoplastic NH4＋ concentration exhibited a steady increase in the three varieties.ZY90 and NC89 had higher and lower apoplastic NH4＋ concentration,respectively.A sharp decrease in glutamine synthetase activity,apoplastic pH and total nitrogen content and a gradual increase glutamate dehydrogenase activity were also found.pH in apoplastic solution was lower than that in mesophyll throughout the experimental period.A significant positive correlation was found between glutamate dehydrogenase activity and apoplastic NH4＋ concentration.Both glutamine synthetase activity and total nitrogen had a significant negative correlation with apoplastic NH4＋ concentration.【Conclusion】 The tolerance to nitrogen nutrition of flue-cured tobacco variety had correlation with apoplastic NH4＋ concentration and the activity of glutamine synthetase and glutamate dehydrogenase at late growth stage.It was deduced that the tobacco variety with high tolerance to nitrogen nutrition has higher apoplastic NH4＋ concentration,glutamate dehydrogenase activity and ammonia volatilization and lower glutamine synthetase activity.