赤霉素对苋菜产量和营养品质的影响及其残留研究

探索赤霉素对苋菜产量和品质的影响以及残留动态,为建立苋菜生产中赤霉素安全、有效使用技术规程提供科学依据。[方法]广州地区夏季苋菜生长到5-6片真叶时,叶面喷施高(90 g/hm2)、中(60g/ hm2)、低(30 g/hm2)三种浓度赤霉素,喷施后测定不同时期的苋菜株高、产量以及维生素C、蛋白质、还原糖、可溶性固形物、粗纤维含量,研究不同剂量赤霉素对株高、产量、营养品质的影响；测定苋菜不同生长期赤霉素残留,获得残留动态以及最终残留。 [结果]中剂量赤霉素处理对株高和产量促进作用显著,喷施后3-10 d样品的平均株高比对照增加11.50 %,平均产量增加27.56 %,达显著水平。其中3、5、7 d样品株高比对照增加达显著水平,分别为10.59%、13.33%、12.71%；5、7、10 d样品产量比对照增加达显著水平,分别为33.41%、44.35%、17.41%。低剂量和中剂量处理后10 d样品中维生素C含量分别比对照增加67.44 %、44.50 %,达显著水平；蛋白质含量分别比对照组增加12.17 %、11.11 %,达显著水平。三种剂量处理后10 d后样品还原糖、粗纤维及可溶性固形物含量与对照组均无显著差异。赤霉素降解动态曲线符合一级动力方程,半衰期为1.24 d；三种剂量处理后5、7、10 d苋菜赤霉素最终残留均值在0.0012-0.0074 mg/kg之间(定量限只到0.01；有效数字过多),远低于日本限量标准0.2 mg/kg。 [结论] 广州地区夏季苋菜生长到5-6片真叶时,叶面喷施60 g/hm2的赤霉素溶液,喷施后10 d采收,赤霉素残留均值为0.002mg/kg,产量比对照增加17.41%,维生素C含量增加44.50%,蛋白质含量增加11.11%,可溶性固形物、还原糖、粗纤维含量差异不显著。建议可用日本肯定列表中的残最大留限量作为广州地区中国苋菜上赤霉素的残留限量标准。

Amaranthus tricolor: Effect of GA3 on Yield and Nutritional Quality and Its Residue Dynamic

To study the effect of GA3 on yield and nutritional quality of Amaranthus tricolor and its residue dynamic, and provide a scientific basis for establishment of technical regulations for safe and effective use of GA3 in edible amaranth cultivation, GA3 was applied at high, middle and low levels (90, 60 and 30 g/hm2) when the edible amaranth had 5-6 leaves in summer of Guangzhou. The height, yield, vitamin C, protein, reducing sugar, soluble solids and crude fiber of edible amaranth in different stages were investigated. Effect of GA3 in different dosages on height, yield and nutritional quality of edible amaranth was discussed. Terminal residues and dissipation dynamic of GA3 were also evaluated. The height and yield of edible amaranth rose significantly under the middle dosage level of GA3. 3-10 d after spray, the average height and yield increased by 11.50% and 27.56% respectively, in comparison with control. The height increased by 10.59%, 13.33%, 12.71% as for pre-harvest interval (PHI) of 3, 5, 7 d respectively. The yield increased by 33.41%, 44.35%, 17.41% as for PHI of 5, 7, 10 d, respectively. As for PHI of 10 d with low and middle dosage level of GA3, the vitamin C content increased significantly by 67.44% and 44.50% respectively, while the protein content increased by 12.17% and 11.11%, respectively. No significant difference was observed on content of reducing sugar, soluble solids and crude fiber with PHI of 10 d at all three dosage levels of GA3 in comparison with control. Thedissipation trend of GA3 in edible amaranth was fitted to a first order kinetics with half-life of 1.24 d. The terminal residues of GA3 in edible amaranth were 0.0012-0.0074 mg/kg with PHI of 5, 7, 10 d under the three application levels, which were far below 0.2 mg/kg, the maximum residue limit (MRL ) of GA3 in edible amaranth in Japan. GA3 was applied at the dosage of 60 g/hm2, when the edible amaranth had 5-6 leaves in summer of Guangzhou, the residue of GA3 was 0.002 mg/kg with PHI of 10 d. Compared with control, the plant yield, vitamin C content and protein content increased by 17.41% , 44.50% and 11.11% respectively. No significant difference was observed on the content of reducing sugar, soluble solids and crude fiber. It is suggested that theMRL of GA3 in edible amaranth from Japan Positive List can be applied in China.