采用盆栽法,以甜菊(Stevia rebaudiana Bertoni)品种‘中山4 号’(‘Zhongshan No. 4’)当年生扦插苗为研究对象,研究不同形态氮肥(硫酸铵、硝酸钠和尿素)及不同施氮量(纯氮)、施磷量(P₂ O₅ )和施钾量(K₂ O)对幼苗生长及糖苷含量和单株积累量的影响。结果显示:随氮肥、磷肥和钾肥施用量的提高,甜菊幼苗的株高、茎粗、叶长、叶宽、单株叶干质量和单株茎干质量均呈先升后降的变化趋势,且总体上与对照无显著差异,仅施磷量300 mg·kg^-1处理组的叶长显著高于对照;根据施肥量与单株叶干质量的回归方程,确定硫酸铵、硝酸钠、尿素、磷肥和钾肥的施用量分别为64. 87、660. 21、735. 84、211. 54 和775. 92 mg·kg^-1 时,幼苗单株叶干质量最高。在硫酸铵处理组中,300mg·kg^-1 处理组甜菊叶片中的莱鲍迪苷A(R-A)含量及甜菊苷(St)、R-A 和总苷的单株积累量以及600 mg·kg-1处理组的St 单株积累量高于对照,多数处理组的St、R-A 和总苷含量及单株积累量均低于对照;在硝酸钠处理组中,1 200 mg·kg^-1处理组的R-A 和总苷含量、600 和900 mg·kg^-1 处理组的St 单株积累量以及300 ~900 mg·kg^-1处理组的R-A 和总苷单株积累量高于对照,其他处理组的St、R-A 和总苷含量及单株积累量均低于对照;在尿素处理组中,1 500 mg·kg^-1 处理组的R-A 和总苷的含量和单株积累量以及600 和900 mg·kg^-1 处理组的R-A 和总苷单株积累量高于对照,其他处理组的St、R-A 和总苷含量及单株积累量均低于对照;各施氮处理组中,仅1 500mg·kg^-1处理组的R-A 含量与对照差异显著,其他指标均与对照无显著差异。在施磷处理组中,100 mg·kg^-1 处理组的R-A 含量以及100 和200 mg·kg^-1处理组的St、R-A 和总苷的单株积累量高于对照,多数处理组的St、R-A和总苷含量及单株积累量低于对照且与对照均无显著差异。在施钾处理组中,各处理组的St、R-A 和总苷含量及单株积累量均高于对照,其中仅900 mg·kg^-1处理组的St、R-A 和总苷含量与对照显著差异。各施肥处理组的St含量占总苷含量的百分率均低于对照、R-A 含量占总苷含量的百分率均高于对照,且总体上与对照无显著差异。经过综合分析,建议在甜菊生育期内的施肥量为纯氮600 ~900 mg·kg^-1 、P₂ O₅ 200 ~300 mg·kg^-1 和K2 O 600 ~900mg·kg^-1,其中氮肥以尿素为宜。

Taking annual cutting seedlings of cultivar ‘Zhongshan No. 4’of Stevia rebaudiana Bertoni as research objects, effects of different forms of nitrogen fertilizer [(NH₄ )₂ SO₄, NaNO₃ and CO(NH₂ )₂ ]and different applying amounts of nitrogen (pure nitrogen), phosphate (P₂ O₅ ) and potassium (K₂ O)fertilizers on seedling growth, and content and accumulation per plant of glycoside were studied by pot method. The results show that with enhancing of applying amounts of nitrogen, phosphate and potassium fertilizers, height, stem diameter, leaf length, leaf width, leaf dry weight per plant and stem dry weight per plant of seedling all appear the trend of firstly increasing and then decreasing, and generally there is no significant difference with the control, only leaf length in the treatment group with applying amount of phosphate fertilizer of 300 mg · kg^-1 is significantly higher than that of the control. According to regression equation between applying fertilizer amount and leaf dry weight per plant, when applying amounts of (NH₄)₂SO₄, NaNO₃, CO(NH₂)₂, phosphate and potassium fertilizers are 64. 87, 660. 21,735. 84, 211. 54 and 775. 92 mg·kg^-1, respectively, leaf dry weight per plant of seedling is the highest. In (NH4)2SO4 treatment group, content of rebaudioside A (R-A) in leaf and accumulations per plant of stevioside (St), R-A and total glycosides of S. rebaudiana in the treatment group with 300 mg·kg-1 and accumulation per plant of St in the treatment group with 600 mg·kg^-1 are higher than those of the control, contents and accumulations per plant of St, R-A and total glycosides in most treatment groups are lower than those of the control. In NaNO₃ treatment group, contents of R-A and total glycosides in the treatment group with 1 200 mg·kg^-1, accumulation per plant of St in the treatment groups with 600 and 900 mg·kg^-1and accumulations per plant of R-A and total glycosides in the treatment groups with 300 - 900 mg ·kg^-1 are higher than those of the control, and contents and accumulations per plant of St, R-A and total glycosides in other treatment groups are lower than those of the control. In CO(NH₂ )₂ treatment group, contents and accumulations per plant of R-A and total glycosides in the treatment group with 1 500 mg·kg^-1 and accumulations per plant of R-A and total glycosides in the treatment groups with 600 and 900 mg·kg^-1 are higher than those of the control, and contents and accumulations per plant of St, R-A and total glycosides in other treatment groups are lower than those of the control. In all treatment group applying nitrogen fertilizer, only R-A content in the treatment group with 1 500 mg·kg^-1 is significantly higher than that of the control, and there is no significant difference between other indexes and the control. In the treatment group applying phosphate fertilizer, content of R-A in the treatment group with 100 mg·kg^-1and accumulations per plant of St, R-A and total glycosides in the treatment groups with 100 and 200 mg·kg^-1 are higher than those of the control, and contents and accumulations per plant of St, R-A and total glycosides in most treatment groups are lower than those of the control with no significant difference. In the treatment group applying potassium fertilizer, contents and accumulations per plant of St, R-A and total glycosides in all treatment groups are higher than those of the control, in which, only in the treatment group with 900 mg·kg^-1  there are significant differences in contents of St, R-A and total glycosides with those of the control. In all fertilizer treatment groups percentages of St content to total glycosides content are lower than those of the control, while those of R-A content to total glycosides content are higher than those of the control, and totally there is no significant difference with those of the control. Based on comprehensive analysis, it is suggested that during growth period of S. rebaudiana, the suitable fertilizer amount is pure nitrogen of 600-900 mg·kg^-1, P₂O₅ of 200-300 mg·kg^-1 and K₂ O of 600-900 mg·kg^-1, in which urea is the suitable nitrogen fertilizer for S. rebaudiana.