黄河口潮滩碱蓬种子萌发与幼苗生长对土壤中氮磷比的响应

Response of Germination and Seedling Growth of Suaeda salsa Seeds from Tidal Marshes in the Yellow River Estuary to N/P Ratio of Soil

由于人类活动的影响,近年来黄河口营养盐入海通量一直维持在较高水平。大量营养盐的输入不仅可对河口潮滩的氮、磷营养水平以及氮磷比产生重要影响,而且其对于湿地植物的种子萌发与幼苗发育亦可能产生深刻影响。为此,于2010年10~11月,在人工气候箱控制条件下,研究土壤中氮磷比对采自黄河口中潮滩和低潮滩的不同表现型的碱蓬(Suaeda salsa)种子萌发和幼苗生长的影响。结果表明,随着培养基盐分的增加,采自中潮滩和低潮滩的碱蓬种子的萌发率都在减小;当氮磷比为9.5时,在无或低盐分(0 m M和300 m M)胁迫下,中等浓度的氮磷配比(4.524 m M氮+0.476 m M磷)有利于采自中潮滩的碱蓬种子的萌发和幼苗生长,低浓度的氮磷配比(0.905 m M氮+0.095 m M磷)则有利于采自低潮滩的碱蓬种子的萌发和幼苗生长;在高盐分(600 m M)胁迫下,高浓度的氮磷配比(9.05 m M氮+0.95 m M磷)对于采自两种生境的碱蓬种子萌发和幼苗生长都具有明显促进作用;当氮磷比为17时,无论在高盐分还是在低盐分胁迫下,高浓度的氮磷配比(9.444 m M氮+0.556 m M磷)都有利于采自两种生境的碱蓬种子萌发和幼苗生长,说明高氮低磷的配比(氮磷比为17)可以有效减缓盐分胁迫对碱蓬种子萌发的危害,使得碱蓬种子可以更快地适应环境而萌发。研究发现,采用平均生长量来描述外界条件影响下碱蓬种子萌发和幼苗平均生长状况是可行的。平均生长量的引入可以真实还原碱蓬种子萌发和幼苗生长的整体状况,是对鲜质量和干质量等表征碱蓬幼苗生长状况指标的一个有益补充。当前,伴随着黄河口潮滩环境氮磷配比的改变,采自两种生境的碱蓬种子萌发的抗盐分胁迫能力都呈增强趋势,其中以采自中潮滩的碱蓬种子抗盐分胁迫能力的增强最为明显,说明下一步通过调控氮磷比可以有效提高采自中潮滩的碱蓬种子对高盐分胁迫环境的适应能力,进而可以将其应用于该区退化湿地的生态恢复。

The response of germination and seedling growth of Suaeda salsa seeds from the middle and low tidal marshes in the Yellow River estuary to N/P ratio of soil were investigated from October to November in 2010 un- der the controlling conditions in an artificial climate chest. The results showed that both the germination rates of the seeds from middle and low marshes decreased greatly with increasing salinity. Under N/P ratio was 9.5 and sa- linity stresses was low （0 mM and 300 mM）, the middle concentration of N and P supplement （4.524 mM nitro- gen＋0.476 mM phosphorus） was favorable for germination and seedling growth of seeds from the middle tidal marshes, while the low concentration of N and P supplement （0.905 mM nitrogen＋0.095 mM phosphorus） was beneficial to those from the low tidal marshes. Under high salinity stress （600 mM）, the germination and seedling growth of the seeds from the middle and low tidal marshes were greatly stimulated by high concentration of N and P supplement （9.05 mM nitrogen＋0.95 mM phosphorus）. As N/P ratio reached 17, high concentration of N and P supplement （9.444 mM nitrogen＋0.556 mM phosphorus） showed great promotion to the germination and seedling growth of the seeds from the middle and low tidal marshes regardless of high or low salinity stresses, indicating that the proportion of high N concentration and low P concentration （N/P ratio was 17） could effectively alleviate the harm for germination of the seeds caused by salinity stress. It was feasible to adopt the index of average growth production to describe the germination and seedling growth of the seeds as affected by external factors since it could truly recover the general status of germination and seeding growth of the seeds. Presently, accompanying with the variations of N and P proportions in the tidal marshes of the Yellow River estuary, the resistance of the seeds from the middle and low tidal marshes to salinity stresses （particularly for those from the middle tidal marsh- es） would show an increasing tendency, indicating that the adaptation capacity for high salinity stress could be pro- moted by controlling the N/P ratios which could be effectively applied for the restoration of regional marshes.