FOLIAR-APPLIED UREA MODULATES NITRIC OXIDE SYNTHESIS METABOLISM AND GLYCINEBETAINE ACCUMULATION IN DROUGHT-STRESSED MAIZE

摘要

Foliar urea has been proved to play a better positive role in enhancing accumulation of nitric oxide (NO) andglycinebetaine (GB) in maize (Zea mays L.) under drought stress (DS). However, it is unclear how foliar urea affectsbiosynthetic metabolism of NO and its relationship with GB accumulation. This study was on investigating the effect offoliar- applied urea on seedlings of maize cultivar Zhengdan 958 grown in a hydroponic medium under DS or No DS.Contents of NO and GB and nitric oxide synthase (NOS) activity increased and peaked 12 h after the treatment. Nitratereductase activity (NRA) followed the similar pattern 6h after the treatment. Under DS foliar urea application increased NRand NOS activity and, thereby, increased NO formation. Therefore, enhancement in activities of both NRA and NOSresulted in an increase of NO accumulation. Foliar- applied urea could induce an increased NO burst by enhanced NOsynthesis metabolism as a nitrogen signal, possibly resulting in GB accumulation under DS.