不同灌溉量对绿洲-荒漠过渡带多枝柽柳幼苗根系生长和分布的影响

为了探讨绿洲-荒漠过渡带上受损柽柳群落幼苗适宜生长的土壤水分条件,在塔南策勒绿洲外围设置A（不灌溉）、B（适度灌溉）、C（充分灌溉）3个处理的田间试验,于7～10月份考察了各处理柽柳幼苗粗根（>2 mm）和细根（<2 mm）生物量积累、空间分布等变化特征。结果显示:（1）随着灌溉量的增加,柽柳根系生物量积累不断增加,且在生长季末（10月份）增速最大,同时细根占总根重的比例从20.5%上升到29.8%,显著提高了幼苗吸收养分和水分的能力。（2）干旱胁迫（处理A）下柽柳幼苗根系的下扎深度大,但水平根幅的扩展却有限;适度灌溉（处理B）的生物量较处理A大,但小于处理C;根系扎根深度表现为处理A>处理B>处理C,各指标均处于中间状态;水分条件最好（处理C）时虽然垂直扎根深度小,但水平根幅最大,可以更有效利用浅层土壤资源。（3）柽柳幼苗大量根系集中在0～40 cm的土壤表层,而且水分条件越好,这种集中趋势越明显;根系生物量随土壤深度的增加呈递减变化,细根的根长密度也有相似变化,但细根的比根长变化规律不明显,这可能与各层土壤微观环境的变化有关。研究表明,灌溉对柽柳幼苗根系的生长和分布有显著影响,充分灌溉下柽柳幼苗根系生物量积累最多且空间分布最大,该灌溉量有利于柽柳幼苗根系的正常生长和合理分布。     

陇东旱塬苹果根系分布规律及生理特性对地表覆盖的响应

为探明陇东旱塬区不同覆盖物对苹果园土壤理化性状、根系分布及根系生理活性的影响,以14年生苹果树为试材,采用土壤剖面分层取样法,调查根系空间分布,并对根系生物量、根长、表面积等进行分析,测定根系活力、抗氧化酶类、活性氧代谢等相关生理指标,同时测定不同深度土层土壤容重、孔隙度等.结果表明: 覆草可有效增大土壤含水量、孔隙度、有机质含量,增幅分别为2.7%～11.6%、3.2%～27.7%、5.1%～36.0%,但土壤容重降低,为清耕(CK)的88.7%～96.4%.CK根系主要分布在距树干30～120 cm范围内的0～60 cm深土层中;覆草、覆膜处理主要分布在距树干0～150 cm、0～60 cm水平范围内的0～100 cm深土层中,以20～40 cm根系最为密集;覆膜处理细根总量仅为CK的96.4%,根系水平分布范围较CK有所减小,0～60 cm内细根占根系总量的51.6%.不同覆盖处理显著增强0～80 cm土层根系活力及抗氧化酶活性,其中覆草处理根系活力为CK的111.3%～136.7%.综合分析根系生长分布与生理活性、土壤理化性状等,认为覆草处理是陇东旱塬区苹果园较为适宜的地表覆盖方式.     

黄土高原不同演替阶段草地植被细根垂直分布特征与土壤环境的关系

研究了黄土区不同演替阶段草地植被细根垂直分布特征与土壤环境的关系,结果表明不同演替阶段草地植被细根生物量、根长密度、表面积、直径和比根长均具有明显的垂直分布特征。细根生物量、根长密度和细根表面积一般随土层加深而逐渐减少,且集中分布于0-40cm土层;随着演替的进行,除20a弃耕地外,0—80cm土层细根生物量、根长密度和细根表面积逐渐增加;除25a弃耕地外,细根直径随演替进行逐渐减小。0～100cm土层土壤含水量随演替进行而增加,不同演替阶段深层土壤水分较表层稳定。土壤容重的变化趋势为9〈4〈15〈20〈25a弃耕地,根系对表层土壤水分和容重的影响较大,而对深层土壤水分与容重影响较少。不同演替阶段细根各参数和土壤水分、容重差异均达到显著水平。各弃耕地细根参数之间,细根参数和土壤环境因子之间存在不同程度的相关关系,土壤含水量在草本植被的不同演替阶段均是影响其细根垂直分布的关键因素。土壤容重在演替早期对草本植被根系的影响较小,随着演替进行其影响作用进一步增强。     

大气增温对杉木幼树根系生物量的影响

为揭示亚热带杉木人工林地下生物量对全球变暖的响应,本研究以杉木幼树为研究对象,在福建三明森林生态系统国家野外科学观测研究站利用开顶式(OTC)大气增温模拟气候变暖,研究增温对杉木幼树根系生物量的空间分布和不同径级分配的影响。结果表明：增温处理后总根系生物量、总细根生物量及总粗根生物量较对照均无显著差异;与对照相比,增温处理显著降低20～50 cm土层的细根生物量占比与0～10 cm土层的粗根生物量占比,但显著提高20～50 cm土层的粗根生物量占比;其余土层细根生物量和粗根生物量较对照均无显著差异;与对照相比,增温处理后0～2、2～5、5～10、10～20和>20 mm径级根系生物量均无显著变化。因此,增温处理下杉木幼树通过降低表层粗根生物量的占比,提高深层粗根生物量的占比以固定和支撑杉木生长,同时通过降低深层细根生物量的占比来维持表层细根生物量以保证水分和养分的吸收;大气增温影响根系生物量的垂直分布和不同径级的分配,在一定程度上影响地下碳分配,可能导致碳循环过程发生改变。     

毛乌素沙地臭柏（Sabina vulgaris）和油蒿（Artemisia ordosica）群落的细根分布特征

用根钻法和细根分级的方法研究了毛乌素沙地臭柏群落、臭柏灌丛、油蒿群落的细根(D≤2 mm, D为根直径)垂直分布,并用渐近线方程Y=1-βd[Y为从地表到一定深度的根量百分比累积值(0～1),d表示土层深度(cm),β为根系削弱系数]描述根系分布与土壤深度的关系.对不同径级臭柏、油蒿细根的β值、根长密度及根面积指数进行计算,结果表明:以15 cm为取样深度级,臭柏和油蒿群落活细根(D≤2 mm)的各月生物量平均值,在0～15 cm 范围内最大,并且随土壤深度增加而减少.臭柏群落、臭柏灌丛、油蒿群落细根生物量垂直分布的β值差异不显著(P＞0.5),但相应层次上的月平均细根生物量,臭柏群落是油蒿群落的6.7～14.6倍(P＜0.05),臭柏灌丛是油蒿群落的14.0～19.2倍(P＜0.05).D≤1 mm与1 mm＜D≤2 mm的细根重量百分比与土壤深度都呈对数关系,但D≤1 mm的细根与土壤深度的相关程度更高.根长密度与根面积指数在各土层的分布有极大的相似性.在臭柏群落、臭柏灌丛、油蒿群落中,D≤2 mm的细根根长密度和根面积指数随土壤深度的增加而减小.月平均值中, D≤2 mm、D≤1 mm、1 mm＜D≤2 mm的细根在0～90 cm的根面积指数总和的大小都是:臭柏灌丛＞臭柏群落＞油蒿群落.     

刺槐和侧柏人工林有效根系密度分布规律研究

通过分层分段挖掘法,对13龄刺槐、侧柏人工林,根区有效根长密度和根重密度的空间分布进行了研究。结果表明,尽管刺槐根系分布深度是侧柏的2倍多,但平均有效根长密度只有侧柏的44．5％。在垂直方向上,两树种有效根系主要分布在0～60cm土层内,然而最大有效根长密度却均位于距地表0～30cm以内。其中,刺槐0～30cm区域内有效根长占总有效根长的51．58％,侧柏占58．38％;刺槐有效根干重占总有效根干重的63．01％,侧柏占71．09％;两树种根系密度分布均随土层深度增加而呈指数形式递减。在水平方向上,刺槐有效根系密度呈二次抛物线型分布、最大有效根长或根密度以距树干30～90cm处最大;侧柏有效根系密度则随着距主干距离的增大而减小。非线性参数拟合分析表明,采用RD=EXP(A BX CZ)函数模型,能较好地反映人工林根系密度的空间分布。     

青杨人工林根系生物量、表面积和根长密度变化

在植物生长季节,采用钻取土芯法对秦岭北坡50年生青杨人工林根径≤2 mm和2～5 mm根系的生物量、表面积和根长密度进行测定.结果表明：在青杨人工林根系(＜5 mm)中,根径≤2 mm根系占总生物量的77.8%,2～5 mm根系仅占22.2%;根径≤2 mm根系表面积和根长密度占根系总量的97%以上,而根径2～5 mm根系不足3%.随着土层的加深,根径≤2 mm根系生物量、表面积和根长密度数量减少,根径2～5 mm根系生物量、表面积和根长密度最小值均分布在20～30 cm土层.≤2 mm根系生物量、表面积和根长密度与土壤有机质、有效氮呈极显著相关,而根径2～5 mm根系的相关性不显著.     

干旱区绿洲灌溉条件下不同树龄轮台白杏根系的空间分布

采用田间分层挖掘法和图像扫描分析法,研究了干旱区绿洲灌溉条件下不同树龄轮台白杏根系的空间分布特征.结果表明:轮台白杏的根系主要由细根(d≤1 mm)构成,中粗根(1＜d≤2 mm)和粗根(d＞2 mm)所占比例较小,树龄5 a、10 a和15 a轮台白杏细根长度分别占根系总长度的90.9％、88.4％和79.9％.随树龄延长,根长密度增加,不同径级根长密度均为15 a＞10 a＞5 a.在垂直方向上,轮台白杏的根长密度呈现出先增加后减小的分布趋势,且各土层根系干质量密度差异显著,树龄5a、10 a和15 a轮台白杏根系干质量密度分布较集中的区域分别为距离树干200 cm以内的30 ～ 80 cm、30～100 cm和30～100 cm深度土层,轮台白杏根系的水平分布特征为距离树干越远根系干质量密度越小,且距树干不同距离处的差异显著.从减小相邻树行间树体根系的交错重叠和降低水肥竞争的角度考虑,在干旱区绿洲灌溉条件下,轮台白杏的栽植行距应≥6 m.     

刺槐和侧柏人工林有效根系密度分布规律研究

通过分层分段挖掘法 ,对 13龄刺槐、侧柏人工林 ,根区有效根长密度和根重密度的空间分布进行了研究 .结果表明 ,尽管刺槐根系分布深度是侧柏的 2倍多 ,但平均有效根长密度只有侧柏的 4 4 .5 % .在垂直方向上 ,两树种有效根系主要分布在 0～ 6 0 cm土层内 ,然而最大有效根长密度却均位于距地表 0～ 30 cm以内 .其中 ,刺槐 0～30 cm区域内有效根长占总有效根长的 5 1.5 8% ,侧柏占 5 8.38% ;刺槐有效根干重占总有效根干重的 6 3.0 1% ,侧柏占 71.0 9% ;两树种根系密度分布均随土层深度增加而呈指数形式递减 .在水平方向上 ,刺槐有效根系密度呈二次抛物线型分布、最大有效根长或根密度以距树干 30～ 90 cm处最大 ;侧柏有效根系密度则随着距主干距离的增大而减小 .非线性参数拟合分析表明 ,采用 RD=EXP A+BX +CZ 函数模型 ,能较好地反映人工林根系密度的空间分布     

毛竹细根分布特征研究

为了解毛竹(Phyllostachys edulis)细根的分布规律,对不同水平距离和土层深度0~1 mm和1~2 mm细根的生物量、比根长、组织密度和根长密度进行了分析。结果表明,随着毛竹年龄的增加,细根生物量和根长密度先上升后降低,根组织密度先降低后升高,比根长呈降低的趋势。细根生物量和根长密度以距竹秆60 cm处最大,根组织密度以20 cm处最大,比根长在40 cm处最大,但他们在距竹秆不同距离间的差异不显著。细根生物量以10~20 cm土层最大,根组织密度以20~30 cm土层最大,细根生物量、比根长、组织密度和根长密度在不同土层间的差异不显著。与1~2 mm细根相比,0~1 mm细根生物量和根组织密度更小,比根长和根长密度更大。因此,毛竹年龄对细根生长具有显著的影响,1年生毛竹有最大的比根长和较大的根组织密度,具有更强的资源利用率。毛竹细根在一定的土层范围内呈均匀分布状态,可更有效地利用特定区域的水肥资源。     

干旱胁迫对花生根系生长发育和生理特性的影响

以花育17号和唐科8号两个花生品种为试验材料,在防雨棚栽培池内进行土柱栽培试验,研究了中度干旱胁迫和正常供水处理下花生生育后期根系形态发育特征和生理特性.结果表明: 唐科8号具有较发达的根系及较高的产量和抗旱系数,花育17号根系对干旱胁迫的适应性小于唐科8号.两品种根长密度、根系生物量均主要分布于0～40 cm土层中,但同一土层内两品种根系性状存在差异.与正常供水处理相比,干旱胁迫处理使花育17号各生育期总根长、根系总表面积和总体积均降低,而唐科8号除花针期显著降低外,其余生育期均明显升高;干旱胁迫增加了两品种20～40 cm土层内根系生物量、根系表面积和体积,而降低了40 cm以下土层内各根系性状;干旱胁迫处理使两品种饱果期40 cm以下土层内根系活力降低,且花育17号降低幅度高于唐科8号.干旱胁迫下两品种生育后期根系发育和生理特性的差异表明其根系在干旱胁迫下对水分吸收和利用存在差异.     

ROOTMAP—a model in three-dimensional coordinates of the growth and structure of fibrous root systems

A model is described which simulates the growth of fibrous root systems. The root growth is specified in terms of growing time, numbers of axes, initiation times of axes, growth rates and branching characteristics of the roots, and characteristics governing the direction of root growth. The model generates a representation of the root system in which the locations of all branches and root tips are recorded in three-dimensional coordinates, and updates this representation in discrete time steps until the specified growing time is reached. Data are presented from a simulation of wheat root growth by the model. The simulated root system is represented pictorially and also graphically in the form of root length and root tip number profiles which are stratified by branching order class. The pictorial representations produced by the model are much more realistic than any which have been produced by past root growth models, and the graphical representations show trends in root length and root tip numbers which are the same as those commonly observed in real roots.     

Drip irrigation,soil characteristics and the root distribution and root activity of olive trees

A study was carried out on the root distribution and root activity of the olive tree (Olea Europaea, L., var. manzanillo) as influenced by drip irrigation and by several soil characteristics such as texture and depth. The experiments were conducted in two plots within a drip-irrigated grove of 20-year-old trees planted at 7×7 m spacing. One soil was a sandy loam, the other a clay-loam. Both cylinder and trench methods were used to determine root distribution. Labelling with ³²P was used to determine root activity. Under dryland conditions the adult tree adapted its rooting system, following the installation of a drip system, by concentrating the roots within the wet soil zones near the drippers. The highest root densities occur in those zones, down to a 0.6 m depth, the most abundant being the <0.5 mm diameter roots. The most intensive root activity was also found in that zone. For a given irrigation system, wet soil bulbs are more extensive and therefore root distribution expands to a larger soil volume when the soil is more clayey and with a hard calcareous pan present at about 0.8 m depth which prevents deep drainage.     

Phosphorylation and dephosphorylation of distinct isoforms of the heavy neurofilament protein NF-H

Summary 1. Previous immunohistochemical studies led to the suggestion that distinctly phosphorylated neurofilament isoforms exist in different types of neurons. We have recently examined this hypothesis by direct biochemical experiments, which revealed that the heavy neurofilament protein NF-H of bovine ventral root cholinergic neurons is more acidic and markedly more phosphorylated than that of bovine dorsal root neurons.2. In the present study we employed this system to study the degree to which distinctly phosphorylated NF-H isoforms differ in the extents to which they can be phosphorylated and dephosphorylatedin vitro. This was performed utilizing alkaline phosphatase and protein kinase PK40^ERK, which is specific to serines of Lys-Ser-Pro (KSP) repeats. The results obtained reveal that:3. The more extensively phosphorylated ventral root NF-H is dephosphorylated more rapidly than dorsal root NF-H.4. Ventral root NF-H and dorsal root NF-H in their native form are both poor substrates of PK40^ERK.5. Following dephosphorylation, ventral root and dorsal root NF-H are phosphorylated extensively and differentially by this kinase. Under these conditions, PK40^ERK catalyzes the incorporation of, respectively, 4.2±1.3 and 2.8±0.6 mol of phosphate per molecule of ventral root NF-H and dorsal root NF-H. The ratio of phosphates incorporated into ventral root NF-H to those incorporated into dorsal root NF-H is 1.46±0.17.6. These findings support the hypothesis that different classes of neurons contain distinctly phosphorylated neurofilaments and show that ventral root and dorsal root neurons are a useful model system for studying the distinct characteristics of neurofilament phosphorylation in different types of neurons.     

Genotypic Variation in Root Morphological Characteristics of Common Bean in Relation to Phosphorus Efficiency (in English)

Root morphology in plants may be related to phosphorus (P) efficiency by affecting the absorption characteristics of the root system. However, genotypic variation in root morphological characteristics of common bean (Phaseolus vulgaris L.) as affected by P availability has not been well clarified. In the present study, systematic studies were conducted in a P-buffered sand culture system using three pairs of common bean parental materials with contrasting root traits in response to P deficiency. The results indicate that P availability significantly affects bean root morphology. Common bean tends to have smaller root system, shorter and coarser roots at low P availability. Genotypic variation in root morphology was observed among different genotypes in response to P availability. The P efficient genotypes appear to have larger, finer and longer root systems than the P inefficient genotypes, and such a variation was particularly obvious in the basal roots. From allomeric analysis, we found that morphological characteristics of the basal roots contribute more to P efficiency than those of the tap roots. Further studies with the F9 recombinant inbred lines derived from one of the most contrasting parental pairs, DOR364 and G19833, confirmed the above findings, indicating that those morphological characteristics are inheritable hence provide potential for genetic improvement. Root morphology in plants may be related to phosphorus (P) efficiency by affecting the absorption characteristics of the root system. However, genotypic variation in root morphological characteristics of common bean (Phaseolus vulgaris L.) as affected by P availability has not been well clarified. In the present study, systematic studies were conducted in a P-buffered sand culture system using three pairs of common bean parental materials with contrasting root traits in response to P deficiency. The results indicate that P availability significantly affects bean root morphology. Common bean tends to have smaller root system, shorter and coarser roots at low P availability. Genotypic variation in root morphology was observed among different genotypes in response to P availability. The P efficient genotypes appear to have larger, finer and longer root systems than the P inefficient genotypes, and such a variation was particularly obvious in the basal roots. From allomeric analysis, we found that morphological characteristics of the basal roots contribute more to P efficiency than those of the tap roots. Further studies with the F9 recombinant inbred lines derived from one of the most contrasting parental pairs, DOR364 and G19833, confirmed the above findings, indicating that those morphological characteristics are inheritable hence provide potential for genetic improvement.     

菜豆根形态特性的基因型差异与磷效率

应用磷控释砂培以及计算机图象分析技术,研究了磷效率差异显的菜豆（Phaseolus vulgaris L.)亲本及其重组自交系后代的根形态特性及其与磷效率的关系。试验结果表明,供磷状况显影响菜豆根系形态学特性。在低磷胁迫下,菜豆根系总根长变短、根部生物量减少,根直径增大。菜豆根形态特性对低磷有效性的适应性反应具有显的基因型差异。在低磷条件下磷高效率基因型的根系比磷低效率基因型相对根部生物量较大、总根长较长,根表面积较大。异计分析表明,菜豆基根根形态特性在低磷条件下的适应性变化对磷效率的贡献远远大于主根,并且这些适应性变化是可以遗传的,表明通过对菜豆根形态特性进行遗传改良来提高磷效率有一定的可行性。     

多花木蓝根截面微观结构对其抗拉特性的影响

根截面微观结构由连通的骨架和相互贯通或封闭的孔洞构成, 其与根系抗拉力学特性有密切的联系。该文通过单根拉拔测试根系力学特性并采用扫描电镜获取根截面微观特征, 探讨根截面微观结构特征与根抗拉力学特性的关系。主要结果显示: 1)根系截面单位面积承受拉力和拉伸应变的能力均随根直径的增大而降低。2)根系抗拉强度和韧性随平均孔径的增加而降低, 其次孔径的均匀性对二者也存在一定的影响。3)导管排列方式随根直径的增加, 呈现单管孔→复管孔→管孔链→管孔团的排列方式, 导管排列方式和分布均匀性对根抗拉力学特性都有影响, 其中排列方式较分布均匀性的影响大。4)根截面管孔面积比对根抗拉特性的影响还受木质部和根皮及导管特征的影响。该研究从根系微观结构的角度揭示了根直径的增大影响截面微观结构进而影响根系的抗拉力学特性, 为进一步解析灌木根系固土力学机制提供了一定的理论基础。     

A plant root system architectural taxonomy: A framework for root nomenclature

Abstract

Research into root system morphology over the last two centuries has developed a diverse set of terminologies that are difficult to apply consistently across species and research specialties. In response to a need for better communication, a workshop held by the International Society for Root Research established some nomenclature standards for root research. These standards and their justification are presented in this study. A framework for a root system architectural taxonomy is created by defining four main classes of root: the tap root, that is, the first root to emerge from the seed; lateral roots, which are branches of other roots; shoot‐borne roots, which arise from shoot tissues; and basal roots, which develop from the hypocotyl, that is, the organ which is between the base of the shoot and the base of the tap root. It is concluded that adherence to the presented taxonomy will reduce confusion and eliminate some of the current confounding of results.     

小麦根系特征对干旱胁迫的响应

干旱胁迫时, 小麦(Triticum aestivum)根系率先产生应激响应, 同时向地上部发出信号, 诱导地上部发生生理反应, 从而提高植株抗旱能力。根系构型包括平面几何性状和立体几何结构(即拓扑构型), 具有遗传稳定性和可塑性。干旱胁迫影响根系理化特性, 如根源化学信号、根系细胞酶类和根系渗透作用的响应。根系通过调整其解剖学结构和水分吸收动力等来适应干旱胁迫。该文从根系构型、理化特性和解剖学结构3个方面, 系统阐述了小麦根系特征对干旱胁迫的响应, 并探讨了其与干旱胁迫的关系和当前研究中存在的问题, 以期为相关研究提供参考。     

典型黑土区主要树种根系构型特征及其对固土能力的影响

为量化典型黑土区主要树种根系构型特征,探究其对固土能力的影响,以该区分布较广的榆叶梅、小叶锦鸡儿、白桦、糖槭、红皮云杉、樟子松单株个体为研究对象,采用全根挖掘和WinRHIZO Pro LA2004分析系统相结合对其根系空间分布、几何形态、分形等特征进行测定,同时采用原位整株根系拉拔的方法量化根系垂直拉拔力。结果表明: 榆叶梅以倾斜根为主,小叶锦鸡儿、白桦、糖槭和红皮云杉以水平根为主,樟子松根系在水平和垂直分布上较为均衡;除白桦总根表面积和红皮云杉总根长外,灌木树种总根长、总根表面积显著大于乔木,落叶阔叶乔木总根长、总根表面积显著大于针叶常绿乔木,白桦总根体积显著大于小叶锦鸡儿、糖槭、红皮云杉和樟子松;榆叶梅、小叶锦鸡儿和白桦根系分形维数和分形丰度显著大于红皮云杉和樟子松;榆叶梅、小叶锦鸡儿和糖槭整株根系平均最大垂直拉拔力显著大于白桦、樟子松和红皮云杉。主要受根系总根长、总根表面积和倾斜根数量的影响,榆叶梅、小叶锦鸡儿和糖槭根系表现出较强的固土能力,可作为典型黑土区水土保持植被构建中优先选择的树种。