Effects of Nano-Devices on Growth, Quality and Activities of Enzymes in Nitrogen Metabolism of Hydroponic Lettuce

To improve yield and quality of lettuce in hydroponic, the growth, quality and activities of enzymes in nitrogen metabolism of lettuce in hydroponics were studied with nanodevices. The results showed that the nitrate reductase activities (NRA) in plants with nanodevices were significantly higher than the control at 16rd day after transplanting (DAT). On the 25th DAT, the shoot fresh weight of lettuce treated with 5.6cm2/L nanodevices was 17.8% higher than the control, while there was no difference in dry weights of shoot among different treatments. The NRA of lettuce increased gradually with the amount of nanodevices increasing from 0 cm2/L to 5.6 cm2/L, then decreased with nanodevices amount increasing. There was no obvious difference in the activities of glutamate dehydrogenase (GDH) and glutamate synthase (GOGAT) among different treatments,while glutamine synthase (GS) activity was enhanced with the increasing of nanodevices amount. On the 34th DAT, the shoot fresh weight of lettuce treated by 5.6cm2/L nanodevices was 11.2% higher than the control. The activities of NR and GS treated by 11.2cm2/L increased 39.7%, 97.7%, respectively compared with CK, while the activities of GDH and GOGAT treated by 5.6cm2/L increased 89.0%, 77.3%, respectively. In treatment with 5.6 cm2/L nanodevices in nutrient solution, the contents of soluble protein, flavonoid, soluble phenolic and ascorbic acid (VC) in lettuce increased 92.8%, 19.8%, 36.7% and 61.5%, respectively.The nitrate content in lettuce significantly increased with the using of nanodevices, but did not exceed the national standard. In conclusion, the yield and quality of hydroponic lettuce were improved by nanodevices, and the activities of enzymes in nitrogen metabolism were enhanced, especially at 25th and 34th DAT and best dosage of nanodevices is 5.6 cm2/L.