淹涝和氮形态对苗期玉米伤流液流量及组分的影响

Effect of Water-logging Stress and Nitrogen Forms on Amount and Solutes Concentration of Bleeding Sap in Maize Plants at Seeding Stage

采用砂培培养方法,比较研究淹涝与否和不同氮形态(铵态氮、硝态氮以及铵硝态氮以1∶1混合)对苗期玉米伤流液流量及组分的影响。结果表明,与非淹涝胁迫条件相比,在淹涝胁迫处理的第3天,铵态氮处理玉米的根、茎鞘和整株的生物量干物质量显著增加,当胁迫延长至7 d时,其叶的生物量干质量的增加幅度也达差异显著性水平。此时,其根、茎鞘和叶的生物量干物质量明显高于硝态氮处理,且其中茎鞘的生物量干物质量也明显高于铵、硝混合处理。尽管在遭受淹涝胁迫3 d时,铵态氮处理的伤流液流量及其中的可溶性糖的量均明显降低,但当胁迫时间延长至7 d时,其根系活力明显增高,伤流液的流量及其中的可溶性糖的量也均恢复至非淹涝胁迫条件下的水平。相对而言,与非淹涝胁迫条件相比,为期3 d的淹涝胁迫显著提高硝态氮处理的玉米植株的根系活力,但降低其伤流液流量及其中的硝态氮的量;且随着胁迫时间的延长,其伤流液中的可溶性糖的量也由遭受淹涝胁迫3 d时的无明显变化的趋势,发展为呈明显的降低趋势;而其夜间伤流液中的氨基酸的量则由明显降低转变为与对照无明显差异;其根系活力也恢复至与对照无显著差异的水平。因此,在不同供氮形态下,苗期玉米的根系对淹涝胁迫的响应也存在阶段性差异,进而影响其对淹涝胁迫的适应性。

Effect of water conditions（water-logging stress and non-water-logging stress）and nitrogen forms（ammonium,nitrate and the mixture of nitrate and ammonium）on concentration and transport of components in bleeding sap of maize（Zea mays L.）plants at seeding stage was carried out by using sand culture experiment.The result showed that,dry weight of root,stem and sheath and total biomass of maize plants increased significantly,when compared with the control under three days of water-logging stress condition.So did the leaves from that time on.As a result,water-logging stress treatment and ammonium supply facilitated all of the roots,stem and sheath and leaves growth of maize plants when compared with nitrate.Furthermore,dry weight of stem and sheath of ammonium-fed plants was significantly higher than that of the mixed nitrogen forms-fed plants.Three days of water-logging stress obviously reduced the amount of bleeding sap and the soluble sugar translocation（exudation weight×concentration）in it.However,seven days of water-logging stressed maize plants supplied with ammonium did not exhibit any negative effect on soluble sugar and free amino acid translocation in the bleeding sap and showed the highest root activity.In contrast,water-logging stress significantly reduced the amount of bleeding sap at night and nitrate translocation to the shoot,and increased the root activity of nitrate-fed plants.The amount of soluble sugar in bleeding sap of nitrate-fed plants gradually reduced along with the increase of stress time,whereas,both of the trend of the reduction in the amount of free amino acid in bleeding sap at night and the increase in root activity of nitrate-fed plants disappeared at the same time.Therefore,it revealed that nitrogen form is a major factor affecting maize plants to adapt to water-logging stress,with the periodic difference existed in the responses of different nitrogen form-fed maize plants to the stress condition.