氮磷添加对滨海新围垦区大叶女贞细根形态特征和生物量的影响

Effects of nitrogen and phosphorus addition on fine root morphological characteristics and biomass of Ligustrum lucidum in coastal new reclamation area

关键词:  氮磷添加, 细根形态, 生物量, 大叶女贞, 新围垦区, 上海

Key words:  nitrogen and phosphorus addition, fine root morphology, biomass, Ligustrum lucidum, new reclamation area, Shanghai

摘要:

为探究氮(N)磷(P)养分梯度分别对滨海新围垦区植物表层(0～10 cm)细根(≤2 mm)形态特征和生物量的影响,该实验以大叶女贞为试材,采用内生长土芯(体积196.25 cm³)施肥法对大叶女贞土壤表层(0～10 cm)的土芯分别进行氮、磷添加实验,分别设每穴0、1、3、5、7、9、11、13、15、17、20 g的施肥梯度,研究N、P养分分别对土壤表层细根功能性状的影响。结果表明:(1)与对照相比,施入3 g N时,细根的长度、表面积、体积、根长密度、根表面积密度、生物量显著增加,增幅分别为62.39%、120.87%、169.97%、59.19%、106.99%和102.75%; 施入5～11 g N时,以上各指标逐渐降低,当N施入量大于11 g时,无根系生长。(2)施入3 g P时,根系的总长度、表面积、体积、根长密度、根表面积密度和生物量显著增加,增幅分别为77.37%、111.15%、147.50%、73.87%、97.88%和98.05%。当P施入量大于5 g时,细根的以上指标逐渐降低,但未出现无根系的状况。施肥促使细根的形态指标和生物量发生了显著变化,植物通过改变细根构型来提高土壤养分的获取能力。综上认为,在距离树干1 m位置的表层土壤中分别施加3 g N或P可显著促进大叶女贞细根的生长。

Abstract:

To explore the effects of nitrogen(N)and phosphorus(P)nutrient gradients on morphological characteristics and biomass of fine root(≤2 mm)of plant surface layer(0-10 cm)in new coastal reclamation areas, Ligustrum lucidum was used as the test material and the fertilization method of ingrown soil cores(volume 196.25 cm³)was used to conduct nitrogen and phosphorus addition experiments on the soil core of the soil surface layer(0-10 cm)of L. lucidum. Suppose the fertilization gradient was 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 20 g per hole. The effects of N and P nutrients on the functional traits of fine roots in the soil surface were studied. The results were as follows:(1)Compared with the control, when 3 g N was applied, the length, surface area, volume, root length density, root surface area density, and biomass of fine roots increased significantly, with the increases of 62.39%, 120.87%, 169.97%, 59.19%, 106.99% and 102.75%, respectively; when 5-11 g N was applied, the above indicators gradually decreased. When the amount of N was applied greater than 11 g, no root grew.(2)When 3 g P was applied, the total length, surface area, volume, root length density, root surface area density and biomass of the root system significantly increased, with the increases of 77.37%, 111.15%, 147.50%, 73.87%, 97.88% and 98.05%. When the amount of P was applied greater than 5 g, the above indicators of fine roots gradually decreased, but there was no rootless situation. Fertilization caused significant changes in the morphological indicators and biomass of fine roots, and plants improved the ability to acquire soil nutrients by changing the structure of fine roots. Therefore, applying 3 g of N or P respectively to the surface soil 1 m away from the trunk significantly can promote the growth of fine roots of L. lucidum.