Spatial heterogeneity of fine root biomass of Pinus massoniana forests in the Three Gorges Reservoir Area, China

Environmental heterogeneity is a constant presence in the natural world that significantly affects plant behavior at a variety of levels of complexity. In order to estimate the spatial pattern of fine root biomass in the Three Gorges Reservoir Area, the spatial heterogeneity of fine root biomass in the upper layer of soils （0-10 cm） in three Mas- son pine （Pinus massoniana） stands in the Three Gorges Reservoir Area, China, was studied in 30 m x 30 m plots with geostatistical analysis. The results indicate that 1） both the live and dead fine root biomass of stand 2 were less than those of other stands, 2） the spatial variation of fine roots in the three stands was caused together by structural and ran- dom factors with moderate spatial dependence and 3） the magnitude of spatial heterogeneity of live fine roots ranked as： stand 3 〉 stand 1 〉 stand 2, while that of dead fine roots was similar in the three stands. These findings suggested that the range of spatial autocorrelation for fine root biomass varied considerably in the Three Gorges Reservoir Area, while soil properties, such as soil bulk density, organic matter and total nitrogen, may exhibit great effect on the spatial distribution of fine roots. Finally, we express our hope to be able to carry out further research on the quantitative relation- ship between the spatial heterogeneous patterns of plant and soil properties.

Response of density-related fine root production to soil and leaf traits in coniferous and broad-leaved plantations in the semiarid loess hilly region of China

Fine roots are the most active and functional component of root systems and play a significant role in the acquisition of soil resources. Density is an important structural factor in forest plantations but information on changes in fine roots along a density gradient is limited. In this study, plantations of black locust (Robinia pseudoacacia L.) and Chinese pine (Pinus tabuliformis Carr.) with four density classes were analyzed for the influence of soil and leaf traits on fine root growth. Fine root biomass increased with stand density. High fine root biomass was achieved through increases in the fine root production and turnover rate in the high-density black locust plantations and through an increase in fine root production in the pine plantations. In the high-density Chinese pine stand, there was a high fine root turnover which, coupled with high fine root production, contributed to a high fine root biomass. Overall, fine root production and turnover rate were closely related to soil volumetric water content in both kinds of plantations, while fine root biomass, especially the component of necromass, was related to soil nutrient status, which refers to phosphorous content in black locust plantations and nitrogen content in Chinese pine plantations. There was a close linkage between leaf area index and fine root dynamics in the black locust plantations but not in the pine plantations.

New Method for Measurement of Plant Roots Specific Surface

To provide enough space to carry all surface charges responsible for high cation exchange capacity of plant roots, large area of the root specific surface is necessary, however all experimental methods used up to date give too small surface area values. In this paper, we propose to measure the plant roots surface area using water vapor adsorption isotherm. This method gives roots specific surface areas compatible to CEC. Methodical aspects of the measurements are described along with theoretical background for calculating specific surface area on the example of roots of barley grown in nutrient solution.

Root Growth of the Annual Tillering Grass Panicum miliaceum in Heterogeneous Nutrient Environments

To study growth responses of the roots of Panicum miliaceum L. to heterogeneous supply of nutrients. The authors analyzed the effects of the nutrient levels in both original patches (O) and destination patches (D) on the root growth of P. miliaceum when its roots were allowed to extend from original patch into destination patch. When the nutrient levels in the original patches were low, coarse root biomass ratio (coarse root biomass in the D/total coarse root biomass), coarse root length ratio (coarse root length in the D/total coarse root length), coarse root surface area ratio (coarse root surface area in the D/total coarse root surface area) and fine root length ratio (fine root length in the D/total fine root length) were greater in the destination patches with lower nutrient levels than in the destination patches with higher nutrient levels, while fine root length, fine root length density, fine root surface index, and fine root surface area density were smaller in the former than in the latter. When the nutrient levels in the original patches were high, fine root length, fine root length density, fine root surface area index and fine root surface density were greater in the destination patches with lower nutrient levels than in the destination patches with higher nutrient levels, coarse roots did not respond to the nutrient levels in the destination patches significantly. When the roots extended from the original patches with the same nutrient level into the destination patches with contrasting nutrient levels, fine root biomass and its percentage allocation did not respond to the nutrient levels in the destination patches significantly, whereas both root length and root surface area did. This indicates that the fine roots of P. miliaceum responded to difference in nutrient supply by plasticity in their length and surface area, rather than in their root biomass.

Differential response of root morphology to potassium deficient stress among rice genotypes varying in potassium efficiency

Disparity in the root morphology of six rice(Oryza sativa L.) genotypes varying in potassium(K) efficiency was studied with three K levels:5 mg/L(low),10 mg/L(moderate) and 40 mg/L(adequate) in hydroponic culture. Morphological parameters included root length,surface area,volume and count of lateral roots,as well as fine(diameter<0.2 mm) and thick(diameter>0.2 mm) roots. The results indicate that the root growth of all genotypes was reduced under low K,but moderate K deficiency increased the root length of the efficient genotypes. At deficient and moderate K levels,all the efficient rice genotypes developed more fine roots(diameter<0.2 mm) than the inefficient ones. Both fine root count and root surface area were found to be the best parameters to portray K stress in rice. In accordance with the root morphology,higher K concentrations were noted in shoots of the efficient genotypes when grown at moderate and deficient K levels,indicating that root morphology parameters are involved in root uptake for K and in the translocation of K up to shoots. K deficiency affected not only the root morphology,but also the root ultra-structure. The roots of high-efficient genotypes had stronger tolerance to K deficient stress for root membrane damage,and could maintain the developed root architecture to adapt to the low K growth medium.

Root Physiological and Morphological Characteristics of Two Rice Cultivars with Different Nitrogen-Use Efficiency

The variation in nitrogen （N） uptake by rice has been widely studied but differences in rice root morphology that may contribute to this variation are not completely understood. Field and greenhouse experiments were carried out to study N accumulation, root dry weights, total root lengths, root surface areas, and root bleeding rates of two rice cultivars, Elio with low N-use efficiency and Nanguang with high N-use efficiency. Low （1 mmol N L^-1） and high （5 mmol N L^-1） N applications were established in the greenhouse experiment, and the N rates were 0, 120, and 240 kg ha^-1 in the field experiments at Jiangning and Jiangpu farms, Nanjing, China. The results showed that the N accumulation, root dry weight, total root length, and root surface area increased with an increase in N application. At the heading stage, N accumulation in the shoots and roots of Nanguang was greater than that of Elio in the field experiments and that of Elio at 5 mmol N L^-1 in the greenhouse experiment. After the heading stage, N accumulation was higher for Nanguang at both 1 and 5 mmol N L^-1 in the greenhouse experiment. The total root length and root surface area were significantly different between the two cultivars. Over the range of the fertilizer application rates, the root lengths of Nanguang at Jiangning Farm were 49%-6170 greater at booting and 26%-39% greater at heading than those of Elio, and at Jiangpu Farm they were 22%-42% and 26%-38% greater, respectively. Nanguang had a greater root bleeding rate than Elio. It was concluded that the N-use efficiency of the two rice cultivars studied depended to a great extent on the root morphological parameters and root physiological characteristics at different growth stages.

Soil nutrients in relation to vertical roots distribution in the riparian zone of Three Gorges Reservoir,China

Since the impoundment of the Three Gorges Reservoir(TGR), the riparian zone has been subjected to numerous environmental changes. This study was conducted to recognize the distribution of grass roots and its impacts on soil nutrients in the water level fluctuation zone of TGR. Roots of four predominant herbaceous plants in the study area, specifically, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, and their corresponding relation with soil nutrient contents were investigated. Root surface area density was determined with Win RHIZO, and the relationships of root distribution with soil depths and soil nutrient contents were studied. The results indicates that most roots are distributed in the top soil layer of 0-10 cm. Estimated root surface area density for the selected grass species ranges from 0.16 to 13.44 cm^2/cm^3, and decreases exponentially with an increase in soil depth. Soil organic matter and total nitrogen contents are significantly lower on bare control area than the corresponding values on the grasslands. Total nutrient contents on grasslands of C. dactylon and H. compressa are higher than those of other grass areas. Root length density and root surface area density are significantly correlated with soil organic matter and total nitrogen content for the four grasslands. The present results suggests that plant roots have significant effects on the distribution of soil nutrients in soil profiles in the riparian zone along the TGR. Nevertheless, additional investigations are needed to reveal the specific interactions between plant roots distribution, soil nutrients and water level fluctuations.

Microstructure of Fine Clay Soils Stabilized with Sugarcane Molasses

Sugar cane molasses has proved cohesive and excellent performance on soil aggregates (fine particles). However, the microstructure of consolidated soil by the molasses is not yet subjected to research. The analysis results of sample without molasses (0%) and consolidated samples at 8%, 12%, and 16% show that the molasses acts on the structure of clayey fine soil developing its microstructure of airy matrix type (sample without molasses (0%) to a microstructure of a qualified type, more solid. Consolidated samples to 8%, 12%, 16% of molasses). We also observe the presence of inter-aggregate pores (mesopores) of similar size in all samples. The results of porosimetrical analyses (BJH) of the sample without molasses and consolidated samples to 8%, 12%, and 16% show that simultaneous porous volumes of samples are reduced with the increasing of molasses quantity. This latter, therefore, acts on the porous volume (micropore 2 nm and mesopore 9 nm) by reducing them which really means, molasses occupies the porous volume of the sample. However, this sample seems not to have any effect on the size of mesopores 9 nm. Thus, this product induces the evolution of the soil structure towards the highly dense and condensed structure. Consequently, materials in consolidated soil by molasses will have mechanical properties far superior to those of materials consolidated soil without molasses.

不同草本植物根系对土壤渗透性的影响

[目的]揭示当地排土场不同草本植物根系对土壤渗透性的影响,阐明预测草本植物根系提升土壤渗透性的最优指标,并得出草本植物根系提升土壤渗透性的最佳径级,为排土场生态修复植物选择提供重要依据。[方法]以海州露天矿排土场为研究地点,以轴根型紫花地丁、根蘖型苦荬菜和根茎型水麦冬为研究对象,采用图片像素换算法量化3种根系在不同土层深度范围内的根系分布特征;并结合渗透试验获取3种草本植物原状根土复合体的渗透参数,进而探究了根土复合体根系分布参数与渗透参数的关系。[结果]3种草本植物均能提升土壤的渗透性能,轴根型、根茎型和根蘖型根土复合体的初始入渗率、稳渗率、平均渗透速率、渗透总量相较于素土分别提升82.23%~254.99%,85.59%~307.63%,72.02%~325.91%,62.93%~246.98%。3种草本植物根系的根长密度和根表面积密度与根土复合体的渗透参数均呈现线性相关,根表面积密度的相关性强于根长密度。3种根系对土壤渗透性的增强作用主要归功于0.5 mm<D≤1.5 mm径级,它们均存在提升土壤渗透性的最佳径级。[结论]草本植物根系能够提升土壤渗透性,根表面积密度是最佳预测指标,且不同根系均存在最佳径级。

Influences of double aerial CO_2 concentration on plant root surface area and viability and infection intensity of vesicular-arbuscular mycorrhizal fungi

Using recently developed methods for root research, an investigation initiated concerning effects of doubled atmospheric CO2 concentration on root surface area and infection of vesicular-arbuscular mycorrhizal （VAM） fungi in seedlings of maize, wheat and soybean. Results showed that doubled CO2 concentration significantly extended root system surface area and promoted VAM fungal infection intensity and viability. However, interspecific variation existed in these responses. It is suggested that plant community succession would be changed due to altered characteristics of roots among species in the future climate.

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

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 cm 3)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。

水泥助磨剂助磨性能的表征方法研究

比表面积是水泥细度常用的表征方法之一,但其是否适合评价助磨剂的助磨性能有待商榷。选用了四种助磨剂进行了粉磨实验,分别测量了被粉磨水泥的负压筛余量、颗粒分布和比表面积。对比发现:各助磨剂都对水泥的负压筛余量和颗粒分布有规律性的影响,表现为负压筛余量变小,颗粒分布变窄,但比表面积没有表现出规律性的变化。根据透气法比表面积测量原理,分析了助磨剂对比表面积没有规律性影响的原因是:添加助磨剂后,空气流过速度增大和颗粒分布变窄。不建议采用比表面积作为助磨剂性能的表征方法。

有机肥替代部分化肥氮对晋西南旱区玉米根系生长及其生理活性的影响

为探究玉米根系分布、生理活性及产量和品质对有机肥替代部分化肥氮的响应,于2021—2022年在山西省西南部旱区,以登海605为试验材料,设置当地农户施氮量(210 kg·hm^(-2),N1)、有机肥替代15%化学氮肥(施入化学氮178.5 kg·hm^(-2),N2)、有机肥替代30%化学氮肥(施入化学氮147 kg·hm^(-2),N3)、有机肥替代45%化学氮肥(施入化学氮115.5 kg·hm^(-2),N4)处理,有机肥施用量根据替代比例计算。通过测定玉米生育期内的土壤水分分布、根系生长特性、根系生理活性及籽粒产量和品质,探究不同比例的有机肥替代化学氮肥对土壤水分、根系生长和根系生理活性的影响,及其与收获期籽粒产量的关系。结果表明,有机肥替代化学氮肥提高了40~80 cm土层中的土壤含水量,尤其在N3处理下,40~60 cm土层中的土壤含水量比其他处理平均高出11.3%~22.6%;有机替代增加了0~40 cm土层中的根长和根表面积,其中,N3处理下的根干重较其他处理提高了6.4%~20.6%;此外,有机替代还通过提高根系活力和氮代谢酶活性促进水肥吸收利用,尤其是0~40 cm土层的根表面积、20~60 cm的根系活力以及氮代谢酶活性的提高对产量产生了正向效应,N3处理的籽粒产量、蛋白质和淀粉含量较其他处理分别提高了4.4%~9.3%、3.3%~12.7%和7.4%~22.4%。因此,在晋西南旱地玉米种植区,推荐将30%的无机氮替换为有机肥,该有机替代比例不仅可以改善土壤的贮水能力,还通过提高根系生长和根系的生理活性促进水肥吸收利用,提高籽粒产量和品质,这对该地区的玉米可持续性生产具有重要作用。

JLMS-54.4水泥立磨系统调试经验总结

某公司新型水泥立磨采用四辊高压设计,首次将单辊碾压力设计为2000 kN,并采用多种减振专利技术,调试期间对高熟料配比下的各比表面积水泥、运行模式进行了探索优化,运行效果良好。

磨细粉煤灰对高温水泥混凝土性能的影响研究

高温水泥直接应用于混凝土生产会对混凝土性能造成不良影响。本文研究了不同掺量和比表面积磨细粉煤灰对高温水泥拌合的混凝土性能的影响规律,结果表明:在保证相同工作性能的情况下,混凝土外加剂用量随着粉煤灰比表面积的增大而降低,但受粉煤灰掺量影响;当比表面积≤710 m^(2)/kg时,磨细粉煤灰可以改善高温水泥混凝土的经时保坍能力,提高磨细粉煤灰掺量,混凝土凝结时间延长,混凝土含气量则因掺量和比表面积表现出不同的规律;当磨细粉煤灰掺量为40%,比表面积为621 m^(2)/kg时,其对高温水泥混凝土的温升抑制较为明显;当磨细粉煤灰掺量为20%时,混凝土的长期抗压强度随着比表面积的减小而增大,增加磨细粉煤灰的掺量,当比表面积为≤621 m^(2)/kg时,高温混凝土的早期和长期强度持续增长。

黄土高原不同水分生态区刺槐细根垂直分布的差异

以生长在陕西黄土高原半干旱气候区安塞县和半湿润气候区长武县的刺槐人工林为研究对象,采用土钻法获取根样,研究不同气候区刺槐细根的垂直分布特征。结果表明:两地刺槐细根分布差异较大,安塞县刺槐细根平均分布深度为250cm,长武为200cm;安塞阴、阳坡立地上刺槐细根表面积特征值分别是长武的5.06和8.29倍。无论是在阴坡还是阳坡立地上,安塞刺槐细根表面积特征值均在土壤表层0～20cm处达到最大值,且随土层加深逐渐减小;长武刺槐细根表面积特征值峰值出现在较深的土层,阴、阳坡均在60cm左右。安塞刺槐细根约80%分布于0～150cm土层中,长武集中在0～100cm土层。此外,两地刺槐细根表面积特征值阴坡大于阳坡。水分条件不同是造成这种差异的主要原因。模型S=AhB(C+Dh+Eh2+Fh3)可以较好地拟合两地刺槐细根的垂直分布特征,安塞县不同立地的拟合决定系数R2均在0.94以上,长武县在0.80以上。

红砂幼苗根系形态特征和水分利用效率对土壤水分变化的响应

为探讨干旱与半干旱区受损红砂种群幼苗适宜生长的土壤水分条件,采用盆栽方法,研究了红砂幼苗在充分灌溉(FI)、适度灌溉(MI)、干旱处理(DT)3个水分处理下根系形态和水分利用效率的变化特征。结果表明:(1)红砂幼苗根系形态因水分条件和根序的不同而各异;随灌溉量的减少红砂幼苗根系直径和根体积均表现为FI>MI>DT,但干旱处理促进了根系的伸长生长和比表面积和比根长增加,根系形态的可塑性是红砂幼苗获取水分适应干旱环境的重要策略之一。(2)随根序的升高,各处理水平下红砂幼苗根长、比根长均显著减少,而其根直径和体积却显著增加,表明红砂幼苗根系内部具有高度的形态异质性。(3)与FI处理相比,MI和DT处理下红砂幼苗根系总生物量分别增加了50.00%、19.23%,但MI和DT处理却显著降低了红砂幼苗地上生物量,特别是叶片生物量下降幅度最大,分别降低了62.15%、83.28%,导致根冠比随灌溉量的减少而逐渐增加。(4)干旱处理显著提高了红砂幼苗的水分利用效率。研究认为,在灌溉量减少的情况下,红砂幼苗可通过根长、根系表面积和体积、直径等形态变化来优化其空间分布构型,以调节植株对水分的利用,提高水分利用效率。

第2代杉木林土壤有机碳、全氮对细根分布及形态特征的影响

以20年生杉木人工林为研究对象，分析了杉木细根的生长分布情况及形态学特征．结果表明：第2代杉木人工林的土壤有机碳与全氮主要分布在0～30cm土壤中，随着土壤深度的增加而明显减少；杉木细根生物量在不同土壤层次间差异显著，随土壤深度的增加而显著减少，主要分布在0～15cm的表层土壤中，占总量的50．35％，15～30cm层占30．04％，30～45cm层占19．61％；细根表面积在不同层次土壤间差异不显著，主要分布在0～30cm层中，为2．86m2·m^-3，占总量的79．88％；随着土壤深度的增加，杉木细根比根长增加不明显；土壤有机碳含量与杉木细根生物量、比根长和根表面积密度之间相关性均不显著；土壤全氮含量与杉木细根生物量和根表面积密度之间存在明显的正相关，与细根比根长存在不太明显的负相关．

沙漠人工植物群落的根系分布及动态

2004年植物生长季，利用根钻取样研究了沙漠4种不同配置类型油蒿与柠条植物群落的根系分布及生长动态；另外，采用挖沟分层取样研究了半固定沙丘两种植物的粗根剖面结构，结果表明：尽管4个样地高峰值和低峰值出现的时间不一致，但沙漠植物细根的生长动态表现为双峰型；整个生长季纯油蒿样地细根密集分布于0～40cm，其余样地密集分布于10～60cm；受一年生植物的影响，9月份4个样地表层（0～30cm）细根的根长密度和根重密度均出现最大值。采用边灌水边取样的办法获得4个样地300cm深的根系数据，4个样地90％以上的细根分布在0～200cm层次，其中纯油蒿样地的根系的最大深度是270cm，其余3个样地均在300cm以下；细根的根长密度和根重密度随深度而减小且呈指数递减形式（P〈0．01）。除纯油蒿样地外的其他3个样地，根瘤的最高值出现在4月份；粗根的根长密度远远小于细根的根长密度。挖沟分层取样研究表明，与柠条相比油蒿具有较高的根冠比；柠条的粗根长主要分布于0～60cm，粗根重主要分布在0～40cm；油蒿的粗根分布比柠条的更浅，粗根长主要分布于0～40cm，粗根重主要分布在0～20cm。

不同氮效率水稻品种根系生理生态指标的差异

以氮素利用效率差异大的两个水稻品种(氮高效品种南光和氮低效品种Elio)作为试验材料,设计高低两个供氮水平,在温室砂培条件下研究了不同氮效率水稻高效吸收利用氮素的根系生物学特性及生理机制。结果表明,在两个供氮水平下,氮高效水稻南光的产量均显著大于氮低效水稻,增幅在50%以上。随着供氮水平的提高,两个水稻品种植株的总吸氮量和干物质量随之增加,氮高效水稻南光的生育后期吸氮量和地上部及根系的生物量显著高于氮低效水稻Elio;氮高效水稻品种南光根系形态参数对氮素营养的响应度高于氮低效品种Elio,高氮处理下,南光较低氮处理分别增加127%(总根长)和114%(根系表面积),而Elio仅增加92%(总根长)和82%(根系表面积),而且Elio在齐穗期后根系形态参数水平下降显著;南光的根系伤流强度在拔节期较氮低效水稻Elio高出11%(1mmolL-1)和32%(5mmolL-1),灌浆期南光较Elio高出12%(1mmolL-1)和12%(5mmolL-1),差异均显著。由本试验结果可推断根系形态及根系活力的差异是造成水稻氮效率差异的重要原因之一。