白三叶入侵对草地早熟禾功能性状及草坪质量的影响

【目的】白三叶入侵会挤占草坪草的生存空间,严重威胁草坪的质量和功能。明晰白三叶（Trifolium repens）入侵对草坪植物草地早熟禾（Poa pratensis）功能性状及草坪质量的影响,可深入了解白三叶入侵机制,为禾本科草坪的建植养护提供理论依据。【方法】以白三叶入侵草地早熟禾草坪为研究对象,采用样地调查方法,考察不同白三叶入侵程度下（对照及轻度、中度、重度入侵）草地早熟禾功能性状及草坪质量的差异特征,并通过隶属函数法综合评价各入侵程度下草坪质量。【结果】（1）随白三叶入侵程度的增加,草地早熟禾各器官碳含量、叶片建成成本及碳氮比、碳磷比和氮磷比逐渐降低,而比叶面积、各器官氮和磷含量增大。（2）同一入侵程度下,草地早熟禾各器官碳、氮和磷含量均表现为叶大于根和茎,碳氮比和碳磷比表现为根和茎大于叶,而其氮磷比表现为茎和叶大于根。（3）随白三叶入侵程度的增加,草地早熟禾草坪密度、质地、绿度指数和均一性降低,而地上生物量和地下生物量增大。（4）隶属函数法综合评价结果显示,草坪质量以白三叶未入侵时最优,重度入侵时最差,且叶碳含量对草坪质量的影响最大。【结论】白三叶入侵改变了草地早熟禾功能性状,降低了入侵区草坪质量,严重影响了草坪景观和功能。     

不同土壤水分条件下土壤容重对玉米根系生长的影响

用玉米作为实验材料进行分根实验。种子根平分在装有土娄土的分隔的白铁皮桶中。土壤容重分 4种处理 :低容重 (两边容重都为 1 .2 0 g· cm-3 )、中容重 (两边容重都为1 .33g· cm-3 )、高容重 (两边容重都为 1 .45g· cm-3 )和混合容重 (一边为 1 .2 0 g· cm-3 ,另一边为 1 .45g· cm-3 )。土壤水分控制在高基质势 (- 0 .1 7MPa)和低基质势 (- 0 .86MPa) 2个水平。结果表明 :当植株生长在高紧实土壤或土壤基质势从 - 0 .1 7MPa降到 - 0 .86 MPa时 ,根长和根干重都显著降低 ;紧实土壤使根长降低的同时还使根的直径增大。然而 ,当植株生长在混合容重土壤中时 ,处在低容重土壤中的根系生长得到加强 ,补偿甚至超补偿高容重土壤中根系生长的不足     

果农复合系统根系分布格局与生长动态研究

对苹果、小麦复合系统根系分布格局生长动态的研究表明：（１）４年生苹果根系垂直分布这１００ｃｍ,其主要分布在２０～６０ｃｍ,可占总根量的８０％以上;小麦根系垂直分布可达８０ｃｍ,０～１０ｃｍ占５５．２％,与苹果根系在空间尺度上不复重叠;而不间作时,苹果根系有上浮趋势。（２）苹果幼树根系的水平分布达２５０ｃｍ,大多在０～１００ｃｍ范围,占４２．４％;间作时两边各留１００ｃｍ的保护行,基本不影响小麦生长     

土壤水分胁迫对设施番茄根系及地上部生长的影响

为了研究土壤水分胁迫对番茄生长的影响,以番茄‘金粉2号’(Jingfen 2)品种为试材,于2013年5—8月间在南京信息工程大学可控试验温室设计正常灌溉(T1)、轻度胁迫(T2)、中度胁迫(T3)、重度胁迫(T4)4个土壤水分处理,观测不同处理番茄植株根系及地上部分的生长状况。结果表明:不同处理的番茄根系生长指标(根系总长度、总表面积、总平均直径、根尖数)的最大值均表现为:T2T3T1T4,比较峰值发现,T2、T3和T4的根系总长度分别为T1的1.8、1.0和0.4倍,总表面积分别为T1的2.3、1.1和0.4倍,总平均直径分别为T1的1.3、1.1和0.6倍,根尖数分别为T1的1.1、1.0和0.5倍;T1、T2和T3处理的番茄根系均集中分布在5—10 cm土层内,而在T4处理下根系集中分布在15—25 cm土层内;番茄的株高、茎粗和叶面积指数大小表现为:T1T2T3T4,T2、T3和T4的番茄株高分别比T1下降11.49%、28.6%和43.98%,茎粗以T4处理最低,为T1的73.57%,T2、T3和T4的叶面积指数分别为T1的81.33%、64.62%和43.37%,各处理间叶面积指数在5%水平下呈现显著性差异。相关分析表明,番茄地上部分和地下部分各项生长指标与土壤体积含水率呈正相关。研究认为轻度土壤水分胁迫对番茄植株地上部分的生长影响不显著,利于根系生长,中、重度土壤水分胁迫明显抑制了番茄植株地上部分的生长,降低根系在土壤中的分布层,研究为设施番茄水分管理提供科学依据。     

土壤水分和氮磷营养对冬小麦根系生长及水分利用的调节

模拟试验研究结果表明：在土壤相对含水量为４０％￣７０％范围内,水分亏缺严重,根水势和蒸腾蒸发量显著降低,根系生长严重受阻,根长变短,根干重降低,随着土壤水分趋于良好,根水势和蒸腾蒸发量显著增加,根干重在土壤相对含水量为５５％￣６２％之间时最大,而土壤相对含水量在５５％上下时根长达最长;土壤水分趋于轻度干旱有利根系下扎,土壤水分趋于良好利于根量增长。氮磷营养对小麦根系生长具有明显的调节作用。磷营养可     

土壤水分和磷营养对小麦根系生长生理特性的影响

采用小偃６号小麦品种,在模拟田间原状土容重的条件下土培,研究了土壤水分和磷营养对小麦根系生长生理特性的效应。结果表明：在土壤相对含水量为４０％─７０％范围内,土壤水分亏缺,小麦根系生长受到限制,根系比表面积（ＲＡ）、根呼吸速率（Ｒｐ）、根水势（Ｒψｗ）和叶片蒸腾强度（ＥＩ）明显降低,根系干物重（ＲＤＷ）减少;轻度干旱有利于根系的延伸生长;在土壤干旱条件下,磷营养可以提高根系ＲＡ,降低根系Ｒｐ,提高Ｒψｗ、增加叶面ＥＩ,促进根系延伸生长,扩大小麦根系对土壤深层水分的吸收和利用,进而促进地下部生长,提高ＲＤＷ。磷除作为一种营养物质促进作物根系生长发育外,在水分胁迫条件下,磷营养可明显改善植株体内的水分关系,增强对干旱缺水环境的适应能力,提高作物抗旱性。促进根系生长,提高水分利用的有效方法是根据土壤水分状况调节磷的用量。     

干旱和盐胁迫对草地早熟禾草坪质量及其叶绿素荧光参数的影响

通过干旱、盐、盐 干旱3种胁迫处理对草地早熟禾草坪质量及叶绿素荧光参数的变化进行测定分析.结果显示,(1)与对照草地早熟禾草坪相比,3种处理均随胁迫时间的延长草坪质量持续下降,且叶片细胞膜完整性、净光合速率(Pn),光合色素含量以及叶片叶绿素荧光参数PSⅡ的最大光化学效率(Fv/Fm)、实际光能转换效率(Fv'/Fm')、PsⅡ反应中心非环式光合电子传递效率(фPSⅡ)和光化学淬灭系数(qP)均呈下降趋势,但不同胁迫处理的下降程度不同,总体表现为:干旱 盐胁迫>干旱胁迫>盐胁迫.(2)随着3种胁迫处理时间的延长,早熟禾叶片非光化学猝灭(NPQ)均有增加,但盐胁迫下变化不显著,而干旱和盐 干旱胁迫下变化显著.结果表明,0.3%的NaCl胁迫对早熟禾的草坪质量、叶片细胞膜完整性以及叶绿素荧光参数的影响较小,而干旱、特别是盐 干旱胁迫的影响较大.     

草地早熟禾种子产量构成因素的品种差异

对草地早熟禾 2 8个品种种子产量及性状进行了研究 .结果表明 ,2 8个品种间种子产量存在极显著差异 (P <0 .0 1) ,最高的品种为Balin和Monoply ,其产量达 6 4 3.4～ 6 5 0 .2kg·hm-2 ,为最低品种Elysee(90 .1kg·hm-2 )的 7.1倍 .生产性状相关分析表明 ,生殖枝数 /株、生殖枝高、花序长及小穗数 /生殖枝 4个性状为影响早熟禾种子产量的主要因素 .依据对种子产量及上述 4个性状测定值的聚类分析 ,可将 2 8个品种的种子生产性能分为极强、很强、强、中等、差和极差 6个类群 ,其中Monoply等 6品种为极强类群 ;Baronie、Balin和Sydsport、Entopper分别为很强和强类群 ;Nublue等 12品种为中等类群 ;Broadway等 4品种和Ram1、Elysee分别为差和极差类群     

草地早熟禾假受精现象的研究

本文运用石蜡切片法、整体透明法研究了草地早熟禾的假受精现象。结果表明,草地早熟禾在两极核清晰可见时,卵细胞就已自发分裂成原胚,此现象占观察总数88％;但是,其极核必需经过受精过程才能发育为胚乳。     

草地早熟禾假受精现象的研究

本文运用石蜡切片法、整体透明法研究了草地早熟禾的假受精现象。结果表明,草地早熟禾在两极核清晰可见时,卵细胞就已自发分裂成原胚,此现象占观察总数８８％;但是,其极核必需经过受精过程才能发育为胚乳。     

Physiological mechanism of hypertolerance of cadmium in Kentucky bluegrass and tall fescue: Chemical forms and tissue distribution

Kentucky bluegrass (Poa pratensis) and tall fescue (Festuca arundinacea) are hypertolerant grasses to soil cadmium contamination. Little information is available on their tolerance mechanism. A sand culture and a hydroponic culture experiment were designed to investigate the Cd chemical form changes and its translocation in different tissues. The results showed that Kentucky bluegrass and tall fescue can tolerate 50–200 mg kg⁻¹ of soil Cd stresses and accumulate as high as 4275 and 2559 mg Cd kg⁻¹ DW, respectively, in their shoots without the loss of shoot biomass. Their Cd hypertolerance was correlated with an increase of the undissolved Cd phosphates in the leaves in both grass species, as determined by sequential solvent extraction procedures. The superior Cd tolerance of tall fescue to Kentucky bluegrass was associated with less Cd translocation into the stele of roots and less Cd transported to leaves. The pectate- and protein-integrated Cd forms may be involved in the symplastic translocation of Cd from cortex into stele, and this may lead the higher Cd concentrations in the stele of roots and then above ground leaves via long-distance transport in Kentucky bluegrass.     

耕作播种方式对稻茬小麦根系发育、土壤水分和硝态氮含量的影响

2016—2018年,以深旋耕播种模式为对照,研究了浅旋耕播种和免耕带旋播种模式对稻茬小麦根系发育、土壤水分和硝态氮含量的影响。结果表明: 孕穗期以前免耕带旋播种和浅旋耕播种处理耕层土壤含水量高于深旋耕播种处理,而硝态氮含量低于深旋耕播种处理。拔节和开花期根重密度和根表面积密度处理间差异不显著。2016—2017年,3种耕播方式的产量和地上部分氮吸收量无显著差异;2017—2018年,免耕带旋播种和浅旋耕播种处理的产量较深旋耕播种分别增加10.9%和10.5%,地上部分氮吸收量分别增加17.5%和12.0%。与深旋耕播种和浅旋耕播种处理相比,免耕带旋播种处理播种效率高、断垄率低。综上,免耕带旋播种处理可提高稻茬小麦的播种质量,增强土壤保墒能力,降低氮淋溶风险,促进产量和环境效益的协同提升。     

不同水分管理模式下免耕抛秧水稻立苗期根系生长特性

在免耕条件下,对3种水分管理模式(水层淹灌、干湿交替灌溉和湿润灌溉)的立苗期根系特性进行了研究。结果表明,除抛栽后第2天,无论晚季或早季,整个立苗期干湿交替灌溉处理的根冠比、单株根生物量、总根数、白根数、一次分枝数量、根系活力、发根力均显著或极显著高于水层淹灌和湿润灌溉处理。水层淹灌处理利于二次分枝根的发生与根系的伸长。湿润灌溉处理更能促进早季稻根毛区生长。     

不同树龄橡胶林土壤水分和细根生物量

采用根钻法,分析了橡胶幼树期(5 a)、初产期(9 a)和旺产期(16 a)林下土壤水分特征及橡胶树细根生物量.结果表明:橡胶树龄越大,土壤含水量越高,而橡胶树细根生物量越少;不同树龄橡胶林0～60 cm土壤含水量随着土层深度的增加而升高,年内变化则呈"双峰"型;不同树龄橡胶树细根生物量最大值均出现在10 cm土层,且随着土层深度的增加而减少,细根生物量年内变化同样呈"双峰"型,但不同树龄细根生物量峰值的出现时间不一致.土壤含水量和土层深度是橡胶树细根生物量的主要影响因子.     

Soil types with different texture affects development of Rhizoctonia root rot of wheat seedlings

The effect of different soil textures, sandy (97.5% sand, 1.6% silt, 0.9% clay), loamy sand (77% sand, 11% silt, 12% clay) and a sandy clay loam (69% sand, 7% silt, 24% clay), on root rot of wheat caused by Rhizoctonia solani Kühn Anastomosis Group (AG) 8 was studied under glasshouse conditions. The reduction in root and shoot biomass following inoculation with AG-8 was greater in sand than in loamy sand or sandy clay loam. Dry root weight of wheat in the sand, loamy sand and sandy clay loam soils infested with AG-8 was 91%, 55% and 28% less than in control uninfested soils. There was greater moisture retention in the loamy sand and sandy clay loam soils as compared to the sand in the upper 10–20 cm. Root penetration resistance was greater in loamy sand and sandy clay loam than in sand. Root growth in the uninfested soil column was faster in the sand than in the loamy sand and sandy clay loam soils, the roots in the sandy soil being thinner than in the other two soils. Radial spread of the pathogen in these soils in seedling trays was twice as fast in the sand in comparison to the loamy sand which in turn was more than twice that in the sandy clay loam soil. There was no evidence that differences among soils in pathogenicity or soil spread of the pathogen was related to their nutrient status. This behaviour may be related to the severity of the disease in fields with sandy soils as compared to those with loam or clay soils. This revised version was published online in June 2006 with corrections to the Cover Date.     

黄土高原21种造林树种的苗木根系活力与土壤含水量关系的研究

通过盆栽试验,测定了不同水分条件下21种苗木的根系活力状况,结果表明：各种苗木可以在一定的土壤干旱范围内适应环境变化。但当土壤含水量低于一定的临界值后,苗木根系将逐步丧失其活力和功能,最终地上部分死亡。苗木的根系活力不仅与土壤含水量有关,而且能在短时间内适应干旱,从而维持较高的根活力水平。在试验苗木当中,耐旱性较强的树种有：山杏、软枣、核桃、枣树、桑树等(经济树种)和国槐(阔叶树种)、侧柏(针叶树种)及紫穗槐、大叶黄杨(灌木)等,其中山杏、软枣、核桃、桑树、侧柏则表现更为突出。     

The phenology of fine root growth in a maple-dominated ecosystem: relationships with some soil properties

A two-year study was undertaken in a maple-dominated watershed of southern Québec, Canada, to examine relationships between trends in fine root growth, stem diameter growth, soil moisture, soil temperature, mineralized-N and extractable-P. Until September, soil temperature was consistently higher in 1995 than in 1994. Apart from the first sampling in mid-May, soil moisture was higher in 1994 than in 1995. In 1994, most fine roots were produced before leaf expansion, whereas in 1995, fine root production peaked in July. Annual fine root production was estimated to be 2.7 times higher in 1994 than in 1995. Stem growth was strongly associated with the seasonal and annual variation in soil temperature. Root and diameter growth were asynchronous in 1994 but not in 1995. Fine root production was associated with two groups of variables: a soil fertility (mineralized-N and extractable-P) group and a physical soil environment (moisture and temperature) group. Our results are consistent with the negative effect of high soil-N fertility on fine root production but are inconclusive as to the positive effect of high soil-P fertility. Soil conditions that are detrimental to root growth such as high N availability and anaerobiosis could modify the normal dynamics of fine root growth.     

中国根层与表层土壤水分关系分析

根层与表层土壤水分的关系, 是由较易获取的表层土壤水分信息去探讨较难获取的深层土壤水分信息的重要桥梁。已有的根层与表层土壤水分关系(简称根表关系)大都基于一种作物或一种生态系统。该文根据我国生态系统研究网络, 包括森林、草地、农田、荒漠和沼泽生态系统的31个站点109个观测场2006年全年3437对根层和表层土壤水分数据, 研究了根表关系以及生态系统、土壤质地、湿润度、植被、土壤厚度和土壤水分量级对根表关系的影响。研究发现, 表层和根层土壤水分存在着线性关系。森林和沼泽的根层与表层土壤水分相关程度较高, 无论是率定段还是校核段, 其决定系数(R²)均大于0.79。农田和草地生态系统的率定段相关性较好, R ²均大于0.80, 校核段相关性稍弱, R ²分别为0.70和0.50。荒漠生态系统的相关关系最弱, 率定段的R²为0.62, 校核段的R²为0.49。土壤质地和生态系统因素对根表关系的影响较为一致。半湿润带、半干旱带和干旱带的根表关系空间分异性最强; 十分湿润带的根表关系与壤土和森林生态系统的根表关系相对应。湿润带内部的根表关系较为一致。将植被对根表关系的影响分为4类, 前两类为根表关系微弱的植被, 由植被本身或者植被以外的地域因素导致, 不适合用根表关系去由表层推算根层土壤水分; 后两类为根表关系良好植被, 区别为服从和不服从关系总线, 可分别用各自的根表关系或者关系总线从表层土壤水分获取根层土壤水分。表层土壤水分与0-20、0-30、……、0-100 cm土层的土壤水分均分别具有较好的相关关系, 但二者的相关性随土层厚度的增加而降低。不过, 即使是土层厚度抵及100 cm, R ²仍能维持在0.79。通过将土壤水分分别除以所有观测数据的最大值(“标甲”法)和各个生态系统数据的最大值(“标乙”法), 发现根表关系不受土壤水分量级本身的影响。     

Different distribution patterns of woody species on a slope in relation to vertical root distribution and dynamics of soil moisture profiles

Distribution patterns along a slope and vertical root distribution were compared among seven major woody species in a secondary forest of the warm-temperate zone in central Japan in relation to differences in soil moisture profiles through a growing season among different positions along the slope. Pinus densiflora, Juniperus rigida, Ilex pedunculosa and Lyonia ovalifolia, growing mostly on the upper part of the slope with shallow soil depth had shallower roots. Quercus serrata and Quercus glauca, occurring mostly on the lower slope with deep soil showed deeper rooting. Styrax japonica, mainly restricted to the foot slope, had shallower roots in spite of growing on the deepest soil. These relations can be explained by the soil moisture profile under drought at each position on the slope. On the upper part of the slope and the foot slope, deep rooting brings little advantage in water uptake from the soil due to the total drying of the soil and no period of drying even in the shallow soil, respectively. However, deep rooting is useful on the lower slope where only the deep soil layer keeps moist. This was supported by better diameter growth of a deep-rooting species on deeper soil sites than on shallower soil sites, although a shallow-rooting species showed little difference between them.