Influence of Mineral Nitrogen and Glycine Concentrations On Growth and Nitrogen Assimilation Enzymes of Tomato (Solanum lycopersicum) Seedling Under Aseptic Hydroponic Cultivation

The experiments undertaken here were designed to determine different N forms applied as mineral nitrogen (NO^-₃-N, NH₄⁺-N) and organic N (glycine ) for the growth and nitrogen assimilation enzymes activities of tomatoes. A tissue culture flask experiment with sponge as substrate was established in tissue culture greenhouse with two different genotypes tomato (Lycopersicon esculentum, Shenfeng918 and Huying932) seedling in vitro hydroponic culture under aseptic conditions. N was applied in nutrient solutions at 3.0mM NO^-₃-N, 3.0mM NH₄⁺-N and and a control receiving no N , but glycine as organic N at 4 different N-application concentration (0, 1.5, 3.0, 6.0mM). Our results showed that the total plant N and biomass of the 2 tomato cultivars treated with mineral and organic N was significantly greater (P < 0.05) than the control treatment. the higher glycine concentration been given, the higher total N and biomass were observed. Tomato plants could grow well in conditions of glycine supply. The highest  dry matter weights and total N we detected in 6.0 mM glycine concentration.There had significant differences between two cultivars (Shengfen918 and huying932). After 21 days of sterile incubation, all treatments sinnificantly enhance soluble protein content in shoot and root compared with control which no N receiving treatment.  For TFAA, NH₄⁺-N or Gly-N treatments significantly increased in shoot and root, NO^-₃-N treatment had little significant effect compared with control treatment. Compared to control treatment, SN, AC and 3.0 Gly trearments all significantly decreased GS activity in shoot and root, NO^-₃-N treatment significantly decreased shoot GPT activity, while NH⁺₄-N and Gly-N treatments had no significant effect on it.while amino acid-N treatment significantly increased NADH-GDH, GOT  and GPT activity in root compared with minreal N (NO^-₃-N, NH⁺₄-N) treatment. NADH-GDH activity in shoot and root, GOT and GPT in root enhanced sharply when Gly-N concentration in the nutrient solutin increased. Furthermore, ammonic-assimilation enzymes activity in root were higher than that in shoot. These results strogenly suggest that agricultural plants (e.g. tomaoto) could effectively use organic nitrogen directly from organic nitrogen sources (e.g., glycine). Growth and nitrogen assimilation enzymes of tomato seedling response to organic nitrogen (e.g., glycine) supply might be related to genotypes and concentrations of organic nitrogen. Further studies such as the contribution of organic nitrogen uptake to the nitrogen nutrition and formation of the competitions between plants and microbes are recommended.