Effect of ammonium and nitrate sole supply and nitrogen levels on nitrogen, phosphorus and potassium content and accumulation of maize (Zea mays L.) under water-logging stress at seedling stage | 铵硝态氮单独供应对苗期淹水胁迫玉米氮磷钾累积的影响

Chinese. 研究不同供氮水平铵态氮（NH4+-N）、硝态氮（NO3--N）对苗期淹水胁迫玉米氮、磷、钾含量及累积的影响，为采取氮营养调控途径优化玉米的氮、磷、钾营养特性及提高玉米的抗涝性提供理论依据。采用室内砂砾培养及模拟淹水胁迫的方法，研究2个玉米品种（“利民15”和“皖玉9号”）分别在苗期单独供应不同水平（3, 7 mmol/L）NH4+-N和NO3--N时，根、茎、叶中氮、磷、钾含量及累积量对淹水胁迫的响应。在2种氮形态和供氮水平下，淹水胁迫分别对低供NH4+-N处理（A3F）和高供NO3--N处理（N7F）苗期玉米生长的影响相对较小，且淹水胁迫对根系生长的抑制效应明显大于地上部。在NH4+-N营养条件下，提高氮素供应水平对苗期淹水胁迫玉米氮、磷、钾的累积无显著影响，但根系氮含量显著增加而钾含量显著降低；在NO3--N营养条件下，提高氮素供应水平则可显著提高苗期淹水胁迫玉米对氮、磷、钾的累积与吸收。在模拟淹水胁迫条件下，提高NH4+-N供应水平可明显增加苗期玉米根系含氮量并降低其根系含钾量，导致氮、钾比例失调，进而降低其耐淹性；但提高NO3--N供应水平则可明显增加苗期玉米对氮、磷和钾的累积与吸收，相对增强了玉米的耐淹性。

English. Effect of water-logging stress on nitrogen, phosphorus and potassium content and accumulation was studied in a sand cultivation experiment, in order to provide a theoretical basis for enhancing water-logging stress tolerance by using nitrogen supply to optimize nitrogen, phosphorus and potassium nutrition. Response of nitrogen, phosphorus and potassium content, and accumulation of two maize cultivars (Wanyu 9 and Limin 15) to nitrogen forms (ammonium and nitrate) and nitrogen levels (3 mmol/L and 7 mmol/L) under water-logging stress at seedling stage were studied in the experiment. The results showed that, maize plants supplied with low level of ammonium-nitrogen (A3F) was higher than those supplied with high level (A7F). In contrast, inhibitory effect of water-logging stress on growth of nitrate-treated maize plants alleviated with increasing nitrate-nitrogen supply. Root appears suffering from much more reduction in biomass when compared with shoot (stem and sheath, and leaves) of maize plants under the stress conditions. Increase in ammonium-nitrogen showed no significant effect on nitrogen, phosphorus and potassium uptake and accumulation, while considerably increased nitrogen content, and reduced potassium content in the root of maize plants at the same time. By contrast, higher nitrate-nitrogen treated plants showed a pronounced increase in nutrients uptake and higher nutrients accumulation in the maize plants under water-logging stress. The presented data revealed that nitrogen form and nitrogen level are two major factors affecting maize plants responses to water-logging stress, and negative effects of the water-logging stress under higher ammonium-nitrogen supply led to the imbalance between nitrogen and potassium in the roots, probably due to the increase in nitrogen content and reduction in potassium content. Contrary to that observed for ammonium-treated plants, plants treated with higher nitrate supply accumulated much more nitrogen, phosphorus and potassium.