红砂和霸王种子萌发对干旱与播深条件的响应

红砂(Reaumuria soongorica)和霸王(Zygophyllum xantho xylum)分别是我国西北干旱荒漠区重要的超旱生小灌木和灌木.试验室条件下,研究了两种灌木种子萌发对干旱胁迫(以PEG模拟干旱条件)和播深的响应.干旱胁迫设0、 -0.3、 -0.6、-0.9、-1.2、-1.5、-1.8、-2.1、-2.4、-2.7MPa共10个处理,播深设0、0 .3,0.5,1.0,1.5,2.0,3.0,4.0cm共8个处理.结果显示模拟干旱条件下,供试种的发芽势(3d发芽率)皆从-0.3MPa起即开始显著下降(P<0.05) .发芽率红砂从-0 .9MPa渗透势、霸王从-0.6MPa开始显著降低;种子萌发的最低渗透势阈值红砂和霸王分别为-1.8MPa和-1.5MPa.干旱胁迫对种子胚芽生长有抑制作用,但轻度干旱可促进初生根生长,重度干旱胁迫抑制初生根生长.播深实验表明,红砂和霸王种子均为子叶出土发芽类型 .一般情况下,供试种随播深增加胚芽长度呈增加而初生根呈下降趋势,但霸王在播于土表时初生根生长受到抑制.实验室条件下,达到最大出苗率的播深红砂为0～0.5cm,霸王为0 ～2cm.在适宜条件下,红砂和霸王种子萌发的最低需水量分别为110%和90%,初始萌发时间分别为40h和48h.红砂种子发芽势低(28%)、萌发持续而分散;霸王种子发芽势高(87%) 、萌发整齐.讨论了两种种子发芽对干旱和播深的响应特征及其生态生物学意义.     

种子特征和播种深度对辽东栎种子萌发和幼苗生长的影响

该文在玻璃温室内的遮阴环境下,采用盆播方法研究了辽东栎种子特征(大小和种皮)和播种深度(0、3、6、10 cm)对种子萌发和幼苗生长的影响。结果表明:(1)辽东栎大种子萌发率、萌发速率、萌发值和萌发指数在所有播种深度均高于小种子。其中非去皮种子萌发率、萌发速率和萌发指数在0 cm播种深度的不同大小种子间差异显著,去皮种子所有萌发参数在6和10 cm播种深度的不同大小种子间均差异显著;去皮可促进大种子萌发,但抑制小种子萌发;不同大小种子所有萌发参数均在0 cm播种深度最大,在10cm播种深度最小。(2)不论有无种皮,大种子萌发幼苗的叶片数、单株叶面积、总干物质质量和根冠比在所有播种深度均大于小种子萌发幼苗;去皮种子萌发幼苗的株高、基径、叶片数、单株叶面积和总干物质质量在所有播种深度均不同程度地小于非去皮种子萌发幼苗,但前者根冠比在0、3、6 cm播种深度大于后者;随着播种深度增大,幼苗株高、叶片数、单株叶面积、总干物质质量和根冠比等生长参数均呈减小趋势,但基径随播种深度增大而增大。     

光照、盐分和埋深对无芒隐子草和条叶车前种子萌发的影响

光照、盐分和埋深对无芒隐子草(Cleistogenes songorica)和条叶车前(Plantago lessingii)种子萌发的影响研究结果显示,无芒隐子草和条叶车前种子为萌发需光性种子。随着盐(NaCl)浓度的增加,2种植物种子的发芽率呈直线下降趋势(P<0.01),但以条叶车前下降较为缓慢。当盐分浓度为0.4 mol.L-1时,2种植物种子皆不能萌发。低浓度的盐分促进胚根的生长,高浓度则表现为抑制作用;盐分对胚芽的生长则一直起抑制作用。2种植物种子发芽率随埋深的增加而减小,当埋深>2 cm时不能萌发。     

Interactive effects of seed availability,water depth,and phosphorus enrichment on cattail colonization in an Everglades wetland

The relative importance of seed availability, waterdepth, and soil phosphorus (P) concentrations oncattail (Typha domingensis pers.) earlyestablishment in an Everglades wetland area wasexamined using seed bank analysis and controlledexperiments. The experiments measured seed germinationand seedling growth in tanks with cattail seedaddition subjected to two P concentrations(un-enriched vs. enriched) and water depth (saturatedvs. flooded soils). A limited seed bank (223 ± 69m²) of cattail was found in the surface soil ofthe area studied. The germination of added seeds wasinhibited under flooded conditions, and only 0.6% ofthe germination was found. In contrast,under-saturated soil conditions, a maximum of 6% and15% germination was observed in P-un-enriched andP-enriched treatments, respectively. High mortality ofseedlings occurred regardless of P treatments followinga cold spell. However, P enrichment resulted inincreased seedling growth and asexual propagation.These results suggested the importance of theconcurrence of appropriate hydrologic regimes, Penrichment, and air temperature on the recruitment ofplant species.     

中国水生态足迹广度、深度评价及空间格局

运用生态足迹方法对水资源进行流量资本和存量资本区分,测算分析了中国31个省市1997—2014年的水生态足迹广度与深度。结果显示:(1)中国的水生态足迹广度受年际水资源量丰枯影响,总体呈波动趋势;各省市的水生态足迹广度存在着明显差异,南方地区水生态足迹广度普遍大于北方地区;(2)研究期内,中国的水生态足迹深度只有1998年为1,其余年份的水资源流量资本已不能满足人类生产生活的需求,需要消耗水资源存量资本;各省市之间水生态足迹深度相差较大,整体上北方高南方低,其中14个省份18年的平均水生态足迹深度为1,平均水生态足迹深度最高的地区是宁夏的308.12;(3)运用空间自相关方法对31个省市的水生态足迹广度和深度进行分析得出,中国省际水生态足迹广度与深度均存在明显的空间集聚现象。水生态足迹广度H-H集聚地区主要集中在中国南方地区,水生态足迹深度H-H集聚地区主要集中在中国北方地区。通过对全国水生态足迹广度与深度的测度分析为水生态足迹分析提供新的研究方法,同时也为区域水资源可持续利用提供理论依据。     

光照、水深交互作用对松嫩湿地芦苇种子萌发的影响

莫莫格国家级自然保护区位于松嫩平原西部, 以保护白鹤(Grus leucogeranus)等珍稀水禽及其栖息地为主要目的。扁秆藨草(Scirpus planiculmis)是莫莫格湿地的重要植物, 也是白鹤在该区停栖的主要食源植物。莫莫格湿地水文恢复后, 芦苇(Phragmites australis)等高大挺水植物大量出现, 阻碍了扁秆藨草的恢复。种子萌发是植物生活史的重要阶段, 对于认识野外植物群落动态和植被管理十分重要。该研究在人工气候箱模拟野外环境条件, 分析了光照(全光、遮阴、黑暗)、水深(0、5、15和30 cm)及其交互作用对芦苇种子萌发的影响。结果表明: 光照和水深变化明显影响芦苇种子的萌发; 最终萌发比例在遮阴和黑暗条件下明显比在全光下高, 在3种光照处理下较深水位(5-30 cm)均抑制了芦苇种子的萌发。芦苇种子萌发也明显受光照和水深交互作用的影响; 在全光条件下, 萌发比例在0 cm水深(86.67% ± 2.36%)显著高于其他较深水位; 在遮阴和黑暗环境下, 0 cm水深与其他水深处理间的差异明显缩小, 这应是在遮阴和黑暗条件下(不考虑水深)萌发比例较高的重要原因。因此, 在芦苇建群初期, 及时进行清除处理并保持一定地表水位可以限制芦苇通过有性繁殖更新, 同时改善地表光辐射等生境条件, 促进扁秆藨草恢复。     

Germination and emergence of Sorghum bicolor. genotypic and environmentally induced variation in the response to temperature and depth of sowing

Abstract The germination of Sorghum bicolor seeds of 9 genotypes was tested at temperatures between 8°C and 48°C on a thermal gradient plate. Samples were tested from three regions of the panicle expected to differ in temperature during grain filling. Seeds of a tenth genotype, SPV 354, produced in controlled-environment glasshouses at different panicle temperatures, were tested similarly. In addition, the emergence of SPV 354 was measured from planting depths of 2 and 5 cm at mean soil temperatures of 15, 20 and 25°C. Four methods of calculating mean germination rate for the nine genotypes were compared. Germination characters like base, optimum and maximum temperature (T_b, T_o, T_m), thermal time (θ)and the germination rate at T_o(R_max showed only small differences between methods. There was a range of genotypic variation in all characters: T_b 8.5–11.9°C; T_o, 33.2–37.5°C; T_m, 46.8–49.2°C; θ, 23.4–38.0°Cd; R_max, 0.69–1.14-d_-1. In contrast, mean germinability (G) was between 90% and 100% over the temperature range 13–40°C. Panicle temperature had no effect on any germination character in SPV 354. However, deeper burial increased θ for emergence and decreased G, irrespective of soil temperature except at 5 cm. Increasing panicle temperature, by reducing seed size, reduced G and increased θ by about 10% only at 15°C and 5 cm depth.     

Integrating flood depth and plant resistance with chlorantraniliprole seed treatments for management of rice water weevil,Lissorhoptrus oryzophilus (Coleoptera: Curculionidae)

Chlorantraniliprole seed treatments in rice provide effective suppression of rice water weevil populations in the United States; however, heavy reliance on prophylactic insecticide treatments as a sole strategy could destabilize management programs for this insect. The present research evaluated the compatibility of seed treatments with two other potential management tactics—plant resistance and shallow flooding–by conducting two split‐plot experiments in 2009 and 2011. In both experiments, no substantial antagonism was found among the 3 different tactics. Statistical interactions in these experiments arose from the strong and persistent effects of chlorantraniliprole on larval densities rather than incompatibility of tactics. In 2009, weevil densities differed among varieties and were significantly lower on the cultivar “Jefferson.” In 2011, weevil densities were reduced significantly in shallow‐flooded plots compared to deep‐flooded plots. Significant reductions in weevil numbers by chlorantraniliprole seed treatments, even at application rates 5 fold lower than commercially recommended rates, demonstrated the potential to reduce application rates of this highly potent larvicide. These latter results suggest that future studies on the relationship between chlorantraniliprole seed treatment rate and weevil fitness are warranted.     

Growth of pikeperch in relation to lake characteristics: total phosphorus, water colour, lake area and depth

The growth of pikeperch Sander lucioperca was studied in 41 lakes in central Finland. The backcalculated average total length of 3 year‐old pikeperch was used as an indicator of growth. The growth correlated positively with total phosphorus and water colour and negatively with lake area and depth. The reason for differences in growth may be differences in the amount of suitable food, foraging success or temperature dynamics in different lakes.     

Effect of minor water depth treatments on competitive effect and response of eight wetland plants

Two facets of plant competition, competitive effect (CE) and competitive response (CR), can be used to explain plant community composition but our understanding of abiotic factors that may differentially affect species’ competitive ability is incomplete. We tested whether water-depth affected CE (ability to suppress neighbour) and CR (avoid suppression from neighbour), and if so whether there was consistence in the rank order of both measures of competition under different water depth treatments. CE and CR were measured and compared for eight wetland plant species (Carex lurida, Carex tribuloides, Elymus virginicus, Juncus tenuis, Lythrum salicaria, Phalaris arundinacea, Rumex orbiculatus and Verbesina alternifolia) at five different water-depth treatments (+2, 0, −2, −4 and −6 cm relative to the substrate). Overall, we found that mean CE was at its lowest value at +2 cm water depth, while mean CR was highest at +2 and −6 cm compared to the other water treatments. There was a significant variation of CE between species, with a defined hierarchical order. Pairwise CE rank order correlations between water depth treatments were significant but CR correlations were generally not. There was no significant correlation between CE and CR. CE was significantly correlated with biomass of species grown alone but CR was not. These findings indicate that CE may be used as a general measure to predict wetland species performance, and thus community assemblage, across a range of water depths. CR does not seem to demonstrate predicable patterns between species and water depth treatments. Our results suggest that competition intensity may be reduced in a non-resource-stressed flooded environment by a reduction in CE, but the corresponding increase in CR could dampen this effect on overall competitive ability.     

灌溉施肥部位对玉米同化物分配和水分利用的影响

用土柱管栽试验方法研究了不同灌溉施肥深度对夏玉米生长发育、地上地下部分同化物分配、产量和水分利用效率的影响。试验结果表明：土表下灌施抑制了玉米生育早期的地上部分生长,使根系向土壤中下层的分布加强,从而保证了作物中后期对水分养分的吸收利用,提高了水分利用效率。在本试验条件下,玉米生长的最佳灌施深度为30cm。     

On the relationship between water table depth and water vapor and carbon dioxide fluxes in a minerotrophic fen

The focus of this study is the relationship between water table depth (WTD) and water vapor [evapotranspiration (ET)] and carbon dioxide [CO₂; net ecosystem exchange (NEE)] fluxes in a fen in western Canada. We analyzed hydrological and eddy covariance measurements from four snow‐free periods (2003–2006) with contrasting meteorological conditions to establish the link between daily WTD and ET and gross ecosystem CO₂ exchange (GEE) and ecosystem respiration (R_eco; NEE=R_eco?GEE), respectively: 2003 was warm and dry, 2004 was cool and wet, and 2005 and 2006 were both wet. In 2003, the water table (WT) was below the ground surface. In 2004, the WT rose above the ground surface, and in 2005 and 2006, the WT stayed well above the ground surface. There were no significant differences in total ET (～316 mm period^?1), but total NEE was significantly different (2003: 8 g C m^?2 period^?1; 2004: ?139 g C m^?2 period^?1; 2005: ?163 g C m^?2 period^?1; 2006: ?195 g C m^?2 period^?1), mostly due to differences in total GEE (2003: 327 g C m^?2 period^?1; 2004: 513 g C m^?2 period^?1; 2005: 411 g C m^?2 period^?1; 2006: 556 g C m^?2 period^?1). Variation in ET is mostly explained by radiation (67%), and the contribution of WTD is only minor (33%). WTD controls the compensating contributions of different land surface components, resulting in similar total ET regardless of the hydrological conditions. WTD and temperature each contribute about half to the explained variation in GEE up to a threshold ponding depth, below which temperature alone is the key explanatory variable. WTD is only of minor importance for the variation in R_eco, which is mainly controlled by temperature. Our study implies that future peatland modeling efforts explicitly consider topographic and hydrogeological influences on WTD.     

播种深度对夏玉米幼苗性状和根系特性的影响

选用郑单958(ZD958)和先玉335(XY335)为试验材料,在砂培和大田条件下设置3、5、7和9 cm 4个播种深度,并在大田条件下以不同播种深度混播作为对照(CK),研究播种深度对夏玉米幼苗性状和根系特性的影响.结果表明： 随着播种深度的增加,夏玉米的出苗率下降,出苗时间延长.ZD958和XY335播深9 cm的出苗率较3 cm的分别降低9.4%和11.8%,出苗时间较3 cm的均延长1.5 d.随着播种深度的增加,幼苗长度及幼苗整齐度显著降低,中胚轴长度显著增加,胚芽鞘长度差异不显著;初生胚根长度逐渐减小,次生胚根总长度逐渐增加,总根长度差异不显著;幼苗与中胚轴的总干质量增加,总根干质量差异不显著.随播种深度的增加,种子萌发时幼苗各部位可溶性糖含量增加,营养物质消耗量增加,幼苗根系生长速度增加,根系活力降低,总节根数及节根层数增加.播深增加后出苗率及幼苗活力的降低导致收获穗数的显著降低,最终影响产量形成.此外,播深一致有利于群体整齐度的提高和群体性状的改善,从而提高产量.     

The influence of ventilation systems on water depth penetration of emergent macrophytes

1. Roots of emergent macrophytes depend on oxygen transported from aerial parts by diffusion and, in some species, by pressurised ventilation. The aim of this study was to determine if species with pressurised ventilation grow in deeper water in situ than species lacking this ability.
2. Species with pressurised ventilation grew significantly deeper than species lacking pressurised ventilation, and this was true in substrates with low as well as high redox potential.
3. Two species with low or non-detectable flow rates ( Schoenoplectus lacustris and Equisetum fluviatile , respectively) were found in unexpectedly deep water. Thus, pressurised ventilation is not a prerequisite for growth in deep water. It is, however, suggested that species with pressurised ventilation have a competitive advantage in deep water resulting in long-term competitive exclusion of species lacking pressurised ventilation.     

南四湖沉水植物物种多样性和功能多样性对水深梯度的响应

从物种多样性和功能多样性探讨沉水植物群落对水深的响应可深刻揭示水深对群落构建的影响机制。以南四湖不同水深沉水植物群落为研究对象,对比分析了群落的9个加权功能性状（株高、茎分支数、茎节数、茎直径、根长、根围直径、生物量分配比、比叶面积、植物体磷含量）、5个物种多样性指数（Berger-Parker生态优势度指数、Margalef丰富度指数、Simpson多样性指数、Shannon-Wiener多样性指数和Pielou均匀度指数）和5个功能多样性指数（功能丰富度FRic指数、功能均匀度FEve指数、功能离散度FDiv指数、功能分散度FDis指数和二次熵Rao指数）以及物种多样性和功能多样性关系对水深的响应规律。研究结果表明：（1）水深可显著改变群落株高、根长、根围直径、比叶面积、生物量分配比和植物体磷含量6个加权功能性状;群落茎分支数、茎节数和茎直径3个加权功能性状对水深变化无显著响应;（2）水深可显著影响群落物种多样性和功能多样性,中等水深处沉水植物群落具有较高的Margalef丰富度指数、Shannon-Wiener多样性指数、Berger-Parker生态优势度指数、Pielou均匀度指数以及功能丰富度FRic指数、功能均匀度FEve指数、功能离散度FDis指数、二次熵Rao指数;（3）水深可改变5个物种多样性指数与功能丰富度FRic指数、功能均匀度FEve指数、功能离散度FDiv指数3个功能多样性指数间的相关关系,但对5个物种多样性指数与功能离散度FDis指数、二次熵Rao指数2个功能多样性指数间的相关关系无显著影响。研究结论为：群落不同测度的物种多样性和功能多样性指数及其相关关系对水深变化的响应迥异,在探讨水深对沉水植物群落构建的影响机制时应从多个方面综合考量。     

黄菖蒲和美人蕉对水深梯度的响应差异

通过野外观测研究了黄菖蒲和美人蕉对水深梯度(10、30、50和70cm)的适应性。结果表明:随着水深的增加(1)黄菖蒲和美人蕉的分蘖数显著减少(P<0.05),但对株高、叶长和叶宽的影响不大;(2)2种植物叶片的叶绿素含量和根系活力均逐渐降低,叶片的丙二醛含量则逐渐升高,其中美人蕉的叶绿素含量、根系活力和叶片丙二醛含量的差异显著(P<0.05),而黄菖蒲仅根系活力的差异显著(P<0.05);(3)叶绿素荧光参数中,PSⅡ的最大光能转换效率(Fv/Fm)、表观电子传递速率(ETR)和光化学淬灭(qP)均呈显著下降的趋势(P<0.05),非光化学淬灭(qN)则显著增加(P<0.05);相对电子传递速率(rETR)及潜在最大电子传递速率(rETRm)、对光能的利用效率(α)和对强光的耐受能力(Ik)也都表现出明显的下降;美人蕉在10cm水深条件下各指标均高于黄菖蒲,但在水深较大的条件下总体上低于黄菖蒲。可见,水深较大时对黄菖蒲和美人蕉的生长产生了抑制作用,且对后者的抑制程度要大于前者。因此,在选择黄菖蒲和美人蕉进行湿地植物修复时,应保持浅水条件以利于其生长,其中黄菖蒲适应的水深(30～70cm)大于美人蕉(10cm...     

Growth characteristics ofNelumbo nucifera Gaertn. in response to water depth and flooding

Three experiments on the effects of water depth and flooding onNelumbo nucifera Gaertn. were made in the artificial environment of concrete ponds. First, plants were harvested in autumn after growing under seven different water levels ranging from 0.2–3 m The number of floating leaves, the total number of leaves and the leaf area index of emergent leaves were greatest in the tanks at 0.5 m depth. The petiole dry weight per unit length of emergent leaves and the ratio of aboveground to belowground biomass rose with increasing water depth up to 2 m. In contrast, that of floating leaves was constant at about 10 mg dry weight cm⁻¹. The proportion of biomass in tubers fell from 20% at 0.2 m to 6% at 2 m. Second, petiole elongation responses to the amplitude of flooding were investigated in early summer. The maximum rate of petiole elongation was 25 cm per day at 2.4 m water depth. This was the maximum depth at whichN. nucifera could grow. No petioles could elongate from 3 m to 5 m depth. Finally, the effects of timing of flooding on growth were investigated. At the end of growing season, the belowground biomass of plants in the flooding treatment in late summer was smallest among the flooding treatment plants (P<0.05), and was most severe when flooding occurred in this season. Based on the results of these experiments, the growth characteristics ofN. nucifera in relation to petiole elongation, biomass allocation, and flooding tolerance were discussed.     

Variability of water supply affected shoot biomass and root depth distribution of four temperate grassland species in monocultures and mixtures

极端降雨事件对生态系统功能影响的研究主要集中在干旱或洪水事件，通常包括全年或某个季度的平均或总降雨量的变化。然而，在不改变平均量或总量的情况下，增加降雨变异性的影响还很少被研究。本研究调查了增加水分供应变异性对单一栽培和混合栽培下4种草原植物的地上和根系生物量以及根系生物量分布的影响。将多年生黑麦草(Lolium perenne L., 浅根)，菊苣(Cichorium intybus L., 深根)，白车轴草(Trifolium repens L., 浅根)和红车轴草(Trifolium pratense L., 深根)种植在中型实验生态系统中。单一栽培条件下种植4株同种植物，混合栽 培条件下每种植物各1株。水分供应变异性处理设置低中高3种水平：与低变异水分供应处理相比，另设置一个中度变异处理(±40%)和高度变 异处理(±80%)，测定了地上和根的生物量，拟合了根系垂直分布模型。研究结果表明，与低变异处理相比，白车轴草，红车轴草和4种植物 混种群落的茎生物量在高变异处理下显著减少。在所有处理中，4种植物混种群落产生的茎和根生物量比单一栽培(超产)中物种表现所预测的要多。在水分变异增加的情况下，菊苣在单一栽培下根系分配了更多的生物量到更深的土层，而白车轴草在单一栽培下根系总生物量显著降 低。这些结果表明，水分供应变异的增加会对单一栽培和混合栽培草地的地上和根的生物量产生负面影响。在野外尺度上，水分变异对多物种 草地系统功能的影响需要进一步研究。