不同氨基酸以及赖氨酸与硝态氮不同配比对白菜生长和品质的影响

  【目的】  探究7种不同氨基酸对大白菜生长及品质的影响，选择影响较明显的氨基酸与硝态氮进行适宜配比，以期为提高白菜产量和品质提供理论依据。  【方法】  试验于2017年在浙江大学紫金港校区人工气候实验室内进行，供试品种为‘浙白6号’(Brassica pekinensis L.)，培育方法为局部无菌水培。试验Ⅰ:在含有1 mmol/L (NH₄)₂SO₄和1 mmol/L NaNO₃的营养液中分别添加7种氨基酸，浓度为0.2 mmol/L，7日龄白菜在该溶液中培养26天后，取样测定白菜生物量及品质。试验Ⅱ:通过试验Ⅰ结果选择对白菜生长和品质影响较明显的赖氨酸，在硝酸钠浓度为0.5、1和3 mmol/L (分别表示为A1、A2、A3处理) 的营养液中，分别加入赖氨酸0.2、0.5和1 mmol/L (分别表示为B1、B2、B3处理)，白菜培养21天后，取样测定白菜生物量及品质。  【结果】  赖氨酸处理白菜生物量、可溶性蛋白质含量和硝酸盐含量均最高，且与部分处理差异显著。丝氨酸处理白菜根系活力和叶绿素含量均最高，且与部分处理差异显著。7种氨基酸对根系鲜重、根冠比、维生素C (V_C) 含量和可溶性糖含量均无显著影响。赖氨酸与硝态氮不同配比试验表明，相同浓度硝态氮处理时，随着赖氨酸浓度的升高，地上部和根系鲜重 (除A2处理外) 均降低，部分处理间差异显著；A1B1、A3B1和A3B2处理的白菜鲜重显著高于其它处理；赖氨酸与硝态氮不同配比对白菜的可溶性蛋白质含量、V_C含量和叶片硝酸盐含量均无显著影响。  【结论】  赖氨酸对白菜生长和品质的影响较显著，且赖氨酸会抑制白菜生长。硝态氮浓度较低时，白菜吸收的赖氨酸可能起到补充氮素营养或调解代谢的作用，以维持白菜正常生长。

Effects of different amino acids and different ratios of lysine and nitrate on the growth and quality of Chinese cabbage (Brassica pekinensis L.)

  【Objectives】  The effects of seven amino acids on the growth and quality of Chinese cabbage were studied for the selection of efficient amino acids, and the suitable ratios of the selected amino acids and nitrate were further tested for the practical application.  【Methods】  Partial sterile hydroponic culture method was used for the hydroponic experiment, which was carried out in the artificial climate laboratory of Zijingang Campus of Zhejiang University in 2017, with the Chinese cabbage cultivar Brassica pekinensis L. as tested materials. In experiment I, seven amino acids were used to treat Chinese cabbage, and the index related to fresh weight and quality of Chinese cabbage were determined. In experiment Ⅱ, according to the results of Experiment 1, the lysine with more significant effects on the growth and quality of Chinese cabbage was selected, lysine concentrations were 0.2, 0.5 and 1 mmol/L (namely B1, B2, B3, respectively), and nitrate concentrations were 0.5, 1 and 3 mmol/L (namely A1, A2, A3, respectively). Lysine mixed with nitrate treated Chinese cabbage, and the index related to fresh weight and quality of Chinese cabbage were determined.  【Results】  The biomass, soluble protein content and nitrate content of lysine treated Chinese cabbage were the highest, and were significantly higher than some other treatments. The root activity and SPAD value of the Chinese cabbage treated with serine were the maximum, and the differences were significant with some other treatments. Different treatments had no significant effect on root fresh biomass, root to shoot ratio, V_C and soluble sugar contents. When nitrate concentration was fixed, the increased lysine concentration decreased shoots and root fresh biomass (except A2 treatment). The differences between some treatments were significant. The fresh biomass of Chinese cabbage treated with A1B1, A3B1 and A3B2 was obviously higher than other treatments. Different ratios of lysine and nitrate had no significant effect on soluble protein, V_C and nitrate contents in leaves of Chinese cabbage.  【Conclusions】  Among the seven necessary amino acids, lysine shows the best effect on the growth and quality of Chinese cabbage. However, amino acids do not show satisfactory effect on the quality of Chinese cabbage. Under normal N supply, high concentration of lysine will inhibit the growth of Chinese cabbage. Only when N nutrition is deficient, lysine might be a supplement nitrogen source for Chinese cabbage.