淹涝胁迫和氮形态对苗期玉米糖、氮代谢底物量的影响

采用砂培培养方法,比较研究淹水和不同氮形态(铵态氮、硝态氮以及铵态氮︰硝态氮为1︰1)对苗期玉米根、茎鞘和叶的糖、氮代谢底物——可溶性糖、还原糖、硝态氮和游离氨基酸等物质含量的影响。结果表明,当淹涝胁迫持续7 d时,在非淹涝胁迫条件下,铵态氮处理的根、茎鞘和叶的可溶性糖和游离氨基酸含量均显著高于硝态氮处理(P<0.05);在淹涝胁迫条件下,硝态氮处理的根、茎鞘和叶的生物量干重显著低于铵态氮处理(P<0.05),其根和叶的生物量干重也显著低于铵态氮、硝态氮混合处理(P<0.05)。与非淹涝条件相比,在淹涝胁迫条件下,硝态氮处理的根系和叶的硝态氮含量显著降低(P<0.05),降低幅度分别高达62.6%和30.0%;此外,与非淹涝条件相比,在淹涝胁迫条件下,铵态氮处理的根的可溶性糖、还原糖以及游离氨基酸含量,茎鞘的可溶性糖和还原糖含量以及叶的可溶性糖和游离氨基酸含量均显著升高(P<0.05),而硝态氮处理仅根、茎鞘和叶的还原糖含量以及叶的游离氨基酸含量显著升高(P<0.05)。因此,在本试验条件下,由于糖、氮代谢底物含量充足,铵态氮处理的苗期玉米具有相对较强的耐淹涝胁迫能力。

Effect of water-logging and nitrogen form on substrates of sugar and nitrogen metabolism in maize (Zea mays L.) at seedling stage

The effects of water stress (water logging and non-water logging) and nitrogen forms (ammonium, nitrate and mixture of both) on concentrations of substrates in sugar and nitrogen metabolism (including nitrate, soluble sugar, reducing sugar and free amino acid) in roots, sheaths and stems, and leaves of maize at seedling stage were analyzed in a sand culture experiment. The results showed that under non-water logging conditions, ammonium treated maize had the highest concentration of soluble sugar and free amino acid in different parts of the plant. Dry biomass of different parts of nitrate-treated maize plants was significantly lower than that of ammonium-treated plants. Root and leaf dry biomasses were also significantly lower in ammonium-treated plants than plants treated with mixed nitrogen after seven days of water logging. Water logging significantly reduced nitrate concentration in roots and leaves of nitrate-treated maize plants by 62.6% and 30.0%, respectively. Furthermore, water logging significantly increased soluble/reducing sugar and free amino acid concentrations in roots, soluble/reducing sugar concentrations in sheaths and stems, and soluble sugar and free amino acid concentrations in leaves of ammonium-fed plants. It, however, increased reducing sugar concentration in roots, sheaths and stems and leaves, and free amino acid concentration in leaves of nitrate-fed plants. Ammonium rather than nitrate or mixed nitrogen alleviated therefore the negative effects of water logging resulting from more substrates of sugar and nitrogen metabolism when ammonium was the solely form of nitrogen.