湿地植物燕子花(Iris laevigata)对模拟施氮的响应研究

Responses of wetland plant Iris laevigatato simulated nitrogen additions

选取吉林龙湾自然保护区一种常见的湿地植物——燕子花(Iris laevigata Fisch.)为研究对象,通过模拟控制实验研究了其在不同氮素添加处理下形态、生理和繁殖三方面特征的响应规律.研究共设置3个氮素处理梯度,即对照(0)、低氮(5g/m2)和高氮(15g/m2).结果表明:随着氮素添加量的增加,燕子花株高、生物量呈现下降的趋势,对照组的株高和生物量均显著高于其他处理下的株高和生物量;而叶片数各处理间无显著差异(P>0.05).随着氮素添加量的增加,净光合作用速率和叶绿素含量也逐渐下降;而丙二醛、可溶性糖、脯氨酸等呈现增加的趋势.各处理间,植株的开花物候和花部综合特征有所差异,但开花持续时间、花粉数、胚珠数、花粉活力、柱头可授性均无显著差异(P>0.05).燕子花在氮元素增加的情况下,其生长表现并不佳,反而可能受到抑制.在今后湿地的保护管理中,应科学控制湿地周围农田耕作等人为活动过程中氮肥的使用,避免氮素通过地下途径进入湿地对燕子花种群更新和生长产生影响.

As an important environmental factor in wetland,nitrogen is an essential element for wetland plant growth.When the quantity of the exogenous nitrogen exceeds the threshold that the plant growth needed,it will not only restrict the growth of the wetland plant,but also affect the regeneration of wetland plant and the stability of wetland ecosystem system.It was important that understanding the response mechanism of wetland plant to nitrogen additions for wetland plant conservation and wetland restoration.Iris laevigata,a common plant in Jinchuan wetland within Jilin Longwan National Nature Reserve,was used as the experimental material to explore the response of morphology,physiology and reproduction under different nitrogen addition treatments：control（0）,low nitrogen（5 g/m^2）,high nitrogen（15 g/m^2）.With the increase of the amount of nitrogen addition,the plant height and biomass showed a decreasing trend.There was no significant difference in leaf number among different nitrogen addition treatments（P〉0.05）.The net photosynthesis rate and chlorophyll content also decreased,while the contents of malondialdehyde,soluble sugar,proline increased with the nitrogen additions.There were differences in flowering phenology and floral traits,but there were no significant differences in flowering duration,pollen and ovule number,pollen viability and stigma receptivity between different treatments（P〉0.05）.The response of the morphological characteristics,physiological characteristics and reproductive characteristics of the I.laevigatato nitrogen additions showed that in the case of increasing the quantity of nitrogen,I.laevigata’s growth performance was not promoted,but restricted.The use of nitrogen fertilizer in the farmland surrounding the Jinchuan wetland may have a certain impact on the I.laevigatapopulation in this wetland,so nitrogen fertilizer should be reasonable conducted in farming activity in order to conserve the I.laevigatapopulation and facilitate the growth and stability of this species.