不同氮素形态及其配比对水培叶用甜菜生长和品质的影响

Effects of different nitrogen forms on the growth and quality of leaf beet

以叶用黄甜菜为试材,采用水培方式,研究不同氮素形态及其配比对生长和品质的影响.结果表明:(1)叶用黄甜菜地上部和根系的生长对营养液中硝铵态氮配比(NO_3^--N∶NH_4^+-N)的需求不同,硝铵态氮配比≤1/2时,植株生长品质较好,硝铵态氮配比为4∶4和2∶6的处理较佳;营养液中的硝铵态氮配比≥1/2时,根系生长较好,硝铵态氮配比为6∶2和4∶4的处理较佳.(2)随着营养液中铵态氮比例的增大,植株的株高、茎粗、最大叶面积和生物量均呈先增后减的趋势,硝铵态氮配比为6∶2的处理较佳;各处理的硝酸盐含量均未超过无公害蔬菜标准;植株的可溶性糖、蛋白质和维生素C含量在硝铵态氮配比为4∶4和2∶6的处理下较佳.可见,叶用黄甜菜地上部与根系生长、地上部形态与品质均受到氮素形态及其配比的影响,且对硝铵态氮配比表现出不同的偏好.综合比较各项指标,铵态氮的比例不宜超过50%,硝铵态氮配比为6∶2和4∶4的营养液配方,可用于叶用黄甜菜的生产栽培.

The effect of different forums and ratios of nitrogen （N） on the growth and quality of leaf beet were investigated by hydro-ponic culture. The results showed that the requirement on NO3^--N and NH4^＋-N varied between the above ground part and root of leafbeet. When NO3^--N/NH4-N ratio was less than or equal to 0.5,plant grew with better quality,with NO3^--N/NH4^＋-N ratio being 4 ： 4 and 2 ： 6. When NO3^--N/NH4^＋-N ratio was more than or equal to 0.5,root developed better,especially with NO3^--N/NH4^＋-N ratio being 6 ：2 and 4：4. With increased NH4^＋-N ratio, plant height,stem width,maximum leaf area and biomass all increased first and then dropped. Their qualities were optimized when NO3^--N/NH4^＋-N ratio was 6：2,without compromising NO3^--N standard of pollution-free vegetables. Nevertheless,levels of soluble sugar,protein and vitamin C were optimal with NO3^--N/NH4^＋-N ratio 4 ： 4 and 2：6. To summarize,above ground part, root,and nutrient quality of leaf beet demonstrated different preferences over N form. Generally, NH4^＋-N ratio should not exceed 0.5 and hydroponic solution with NO3^--N/NH4^＋-N ratio being 6 ： 2 and 4 ：4 is applicable to leaf beet cultivation.