氮素形态对菠菜硝酸盐及草酸含量的影响

Effects of Nitrogen Forms on Content and Distribution of Nitrate and Oxalate Forms in Spinach Plants

采用水培试验,研究了不同铵硝配比对菠菜体内硝酸盐和各形态草酸含量及分布的影响。结果表明,生物量随供铵比例的增加先显著升高,后显著下降,在铵硝比为25/75和50/50时具有最高生物量。各器官的硝酸盐含量随着供铵比例的升高而显著下降,叶片的草酸总量和可溶态草酸随营养液中铵态氮比例的升高显著降低,而叶柄和侧根的草酸含量在铵硝比为50/50时最低,主根的草酸含量也随铵态氮比例的增加而下降。草酸在菠菜各器官的含量为叶片>主根>叶柄>侧根,并且叶片含量要远远高于其它器官。菠菜体内的草酸以可溶态为主,除在单独供铵处理的叶片中仅占总草酸含量的38%以外,其它处理的均占草酸总量的69%以上。可见,调节营养液中铵硝比例可以调控菠菜体内各形态的草酸含量。铵硝比为25/75和50/50时不仅有利于菠菜生长,而且可降低菠菜体内的可溶态草酸和草酸总量。

A hydroponic experiment was carried out to study effects of different ammonium/nitrate ratios on content and distribution of nitrate and oxalate in spinach. The results showed that biomass increased with increased ammonium proportion firstly, then decreased obviously and spinach had the highest biomass as ammonium/nitrate ratios were 25/75 and 50/50. Nitrate content of different tissues decreased markedly with ammonium proportion increasing. Total oxalate and soluble oxalate content of leaf decreased obviously in response to elevating ammonium proportion, while oxalate content of petiole and lateral root was the lowest as ammonium/nitrate ratio was 50/50, oxalate content of tap root decreased with increasing ammonium proportion, too. Distribution of oxalate in different tissues of spinach was uneven, and decreased in the following order： leaf 〉 tap root 〉 petiole 〉 lateral root, and oxalate content of leaf was far higher than that of other tissues. Soluble oxalate was predominant form of oxalate in spinach, which occupied up to more than 69% of total oxalate in the other treatments except that soluble oxalate constituted 38% of total oxalate in leaves as ammonium is sole nitrogen resource. Therefore, ammonium/nitrate ratios of 25/75 and 50/50 are benefit for growth of spinach and can reduce soluble oxalate and total oxalate content in spinach.