根茎型禾草繁殖途径的研究进展

从根茎类禾草种子的落粒性、分蘖特性、营养分配规律、营养生长与生殖生长发育规律四个方面对根茎类禾草近几年的研究报道进行了综述。     

松嫩平原几种根茎型禾草种群的营养繁殖特性及其持续更新分析

根据对典型群落随机取样的调查与观测，分析了松嫩平原几种根茎型禾草种群的营养繁殖特性及其持续更新机理。根茎型禾草能够不断生产营养繁殖芽使种群持续更新。在松嫩平原８￣１０月份是根茎型禾草种群营养繁殖芽生产的旺盛时期。牛鞭草种群的芽库１００％为根茎芽。羊草、拂子茅、假苇拂子茅、硬拂子茅、冰草、光稃茅香、野古草７个种群的芽库是由根茎芽和分蘖节芽组成。在两种形式芽输出成株的比率中，根茎型禾草种群普遍以根茎芽     

小麦族多年生根茎类禾草的生态地理分布及利用

分析了小麦族各属根茎类禾草在我国和世界的种数分布、主要种的生态类型及生境特征、建群种或优势种群落的植物组成生态类群和地理分布,概述了我国主要野生种和外来种在草地建设和植被恢复中的利用特点.     

小麦族多年生根茎类禾草的生态地理分布及利用

分析了小麦族各属根茎类禾草在我国和世界的种数分布、主要种的生态类型及生境特征、建群种或优势种群落的植物组成生态类群和地理分布,概述了我国主要野生种和外来种在草地建设和植被恢复中的利用特点。     

围栏封育和长期刈割对松嫩草地羊草和野古草种群营养繁殖特征的影响

营养繁殖是无性系禾草维持种群更新的主要方式之一,产生的潜在种群在预测种群空间结构和动态中发挥着重要作用。围栏封育和长期刈割等利用方式可以直接或间接影响植物的生长发育和繁殖策略。本研究以松嫩草地常见优势种羊草和伴生种野古草为研究对象,对围栏封育和长期刈割下两种禾草的分蘖节与根茎产生潜在种群的组成、大小和营养繁殖力进行对比分析。结果表明：两种利用方式下两种禾草的潜在种群均由分蘖节与根茎产生的芽和苗组成。羊草和野古草潜在种群分别由3和2个龄级组成,均为1龄潜在种群所占比例最高。相比围栏封育,长期刈割显著促进两种禾草分蘖节和根茎上的芽输出成苗,并且对羊草的促进作用高于野古草,羊草的分蘖节与根茎产生的总苗数在两种利用方式下均显著高于野古草。长期刈割显著促进羊草潜在种群的形成,不利于野古草潜在种群的形成。长期刈割能促进两种禾草种群的分株和根茎营养繁殖力,但未达到显著水平。羊草在围栏封育中采取产生大量芽和部分苗以增加潜在种群、在长期刈割中采取产生大量苗以顺利越冬成株的营养繁殖对策;野古草在围栏封育中采取只产生芽、而在长期刈割中采取产生相近比例芽和苗的营养繁殖对策。总的来说,两种利用方式下羊草与野古草...     

3种根茎型禾草无性繁殖时空扩展初探

以青海扁茎早熟禾Poa pratensis var. anceps cv.Qinghai、草原看麦娘Alopecurus pratensis、无芒雀麦Bromus inermis 3种根茎型禾草为材料,进行无性繁殖,并从地上和地下部分比较了3种根茎型禾草无性繁殖的时空扩展情况.结果表明:3种根茎型禾草分蘖株数、根茎数、侵占面积随着生长时间的增加存在显著差异(P<0.05),移植当年青海扁茎早熟禾分蘖株数可达68个/株、根茎数可达24个/株、侵占面积可扩展到731.2 cm2;分别较草原看麦娘多12个/株、2个/株、91.1 cm2;分别较无芒雀麦多22个/株、5个/株、321.9 cm2.3种根茎型禾草移植当年均能成熟,其中青海扁茎早熟禾成熟最早,草原看麦娘次之,无芒雀麦最晚,时空扩展速度表现为青海扁茎早熟禾>草原看麦娘>无芒雀麦.3种根茎型禾草分蘖株数与侵占面积之间呈线性关系,根茎平均长度与侵占面积呈指数关系.     

根茎类型牧草的地上生物量和矿质元素累积

研究了羊草、赖草和中间偃麦草等根茎禾草干物质及N、P、K的累积规律。结果表明，3种禾草的地上生物量和大量元素的累积规律相近；短根茎的中间偃麦草具有较高的生物量和N、P、K的累积量，而根茎较长的羊草和赖草间则在这些项目上差异不大。     

刈割制度下羊草草原地上生物量的动态变化机制

基于长期定位控制试验,研究了割一年休一年刈割制度对羊草草原地上生物量的影响。结果表明,演替过程可以分为两个阶段,1982~1998年期间植物群落地上生物量显著下降,而且与根茎型禾草地上生物量呈显著正相关。灌木半灌木和根茎型禾草与高大丛生禾草和矮丛生禾草呈不显著负相关,根茎型禾草和矮丛生禾草与杂类草呈负相关;1998~2014年期间植物群落地上生物量没有显著上升,而且与高大丛生禾草、矮丛生禾草和杂类草地上生物量呈显著正相关,根茎型禾草与高大丛生禾草和杂类草呈不显著负相关。刈割对羊草典型草原植物群落地上生物量的作用不仅受刈割制度的影响,还要受刈割年份及演替阶段的影响。     

兰州市草坪禾草根腐病的发生及病原菌鉴定

2007-2008年对兰州市13个小区混播草坪禾草根腐病症状表现和发病情况进行了调查。结果表明,发病严重的草坪禾草根腐病发病率为83.33%,病情指数为36.67。该病在草坪禾草不同部位上引起的症状不同,将其归纳为3种症状类型:叶尖黄化型、叶片中部缢缩型和根茎部褐变腐烂型。经对草坪禾草根腐不同发病部位进行分离培养,致病性测定等确定了引起草坪禾草根腐病的主要致病菌为腐霉属(Pythium spp.)的瓜果腐霉(P. aphanidermatum),根茎部病原菌分离频率达100%。潜育期测定结果表明在温度35℃,湿度90%的条件下该病原菌的潜育期最短为14～15 h。     

内生真菌对禾草类植物抗旱性的影响

综述了国内外近年来关于内生真菌Neotyphodium对禾草类植物抗旱性方面的研究成果。结果表明:与不带菌禾草相比,带菌禾草的抗逆性强、产量高,特别是内生真菌的侵染可增加宿主植物的抗旱性。据报道,内生真菌主要是通过促进植株根系发育、叶片生长、气孔开闭、渗透调节、抗氧化保护系统等来提高禾草类植物的抗干旱胁迫能力。但也有学者认为并非所有内生真菌对宿主禾草的抗旱性都有增益作用,内生真菌与禾草的共生关系还很大程度上决定于宿主、内生真菌基因型和生境的相互关系。在未来的研究中应以内生真菌-禾草共生体的抗旱机理、生物学特性和群体特征为重点;此外利用真菌-禾草共生体的抗旱特性开展优良牧草草坪草选育,发挥内生真菌在天然草地中的生态作用也是重要的研究方向。     

禾本科草本植物根状茎发育调控机理研究进展

根状茎是匍匐的地下茎,为多年生草本和其他单子叶植物通过无性繁殖进行克隆生长的营养器官。根状茎的持续分化和横向延伸生长,赋予了根状茎类禾草很强的水平拓展迁移能力和抗扰动能力,无论在天然草原群落构成还是在改善退化草原、荒漠、沙丘等脆弱生态系统中均发挥了重要作用。根状茎的分化和生长发育是一个复杂的过程,受内在因素和外在刺激的协同调控。通过梳理近年来禾本科草本植物根状茎分化和发育的研究文献,从生境异质性、植物激素及关联基因等方面初步综述了根状茎生长发育调控和响应因素,为深入开展根状茎发育研究以及揭示根状茎型禾草空间分株放置的思维和生态适应的逻辑提供了理论借鉴。     

Grass Yields Under Clipping and Watering Explain Varied Efficacy of Management Intensive Grazing on Rangelands

Management intensive grazing (MIG) may not maximize plant productivity on rangelands because of morphophysiological traits of grassland vegetation. We examined defoliation and moisture effects on the biomass yield of rhizomatous and caespitose grass pairs that were either phylogenetically similar or of similar agroclimatic adaptation, including two agronomic grasses. From relatively low to high moisture regime adaptation, species pairs included western wheatgrass (Pascopyrum smithii [Rydb.] A. Love) and needle-and-thread (Hesperostipa comata [Trin. & Rupr.] Barkw.), northern wheatgrass (Elymus lanceolatus [Scribn. & J.G. Sm.]) and western porcupine grass (H. curtiseta [Hitchc.] Barkw.), plains and foothills rough fescue (Festuca hallii [Vasey] and F. campestris Rydb.), and smooth and meadow brome (Bromus inermis Leyss. and B. riparius Rehm). Response variables were shoot yield, root-shoot ratio, and water-use efficiency. We hypothesized that caespitose grasses, regardless of their origin or adaptation to agroclimate regime, would respond more determinately in biomass accumulation. Defoliation effects on shoot biomass were more pronounced under high moisture. Low intensity ? high frequency defoliation yielded similarly to deferred controls in all grasses, and the same was true for high-intensity ? low-frequency (HILF) defoliation in 1 rhizomatous grass. Three of the 4 rhizomatous grasses and 1 caespitose grass yielded greater under HILF defoliation compared with high-intensity ? high-frequency defoliation. Caespitose grasses allocated more biomass to roots under low moisture conditions. Water-use efficiency decreased under high moisture conditions and more intense and/or frequent defoliation and peaked in agronomic grasses. Overall, our results suggested that growth patterns corresponded more with phylogenetic similarity as opposed to growth form. A conceptual model from these results showed that across all species, only the introduced bromes generated greater biomass under HILF defoliation, and this may explain why past research consistently concludes that MIG does not enhance plant productivity on rangelands.     

刈割和养分回添对羊草草原植物群落生物量及其构成的影响

基于2011年开始的养分回添控制试验,研究锡林郭勒盟草原羊草+克氏针茅+糙隐子草群落在不同肥料(氮、植物割取部分和有机质)对羊草割草场植物群落地上生物量的影响。结果表明:与不刈割相比,刈割+有机质回添、刈割+植物回添和刈割处理显著降低了植物群落地上生物量,但刈割+N素回添处理生物量并没有显著降低。4种处理均增加杂类草和一、二年生植物的地上生物量。与单纯刈割相比,刈割+植物回添处理可增加根茎禾草生物量;刈割+N素回添处理显著增加丛生型禾草地上生物量。与单纯刈割相比,刈割+植物回添处理增加了羊草(Leymus chinensis)种群地上生物量,刈割+N素回添处理增加克氏针茅(Stipa krylovii)种群地上生物量并显著增加糙隐子草(Cleistogenes squarrosa)生物量。这说明养分回添对植物群落地上生物量的影响,不仅与所施肥料种类和施肥量有关,还与该草原植物群落物种组成有关。     

行间种不同草后对幼龄苹果树光合特性的影响

为了解果园种草后不同草种对苹果树光合特性的影响,于苹果园建植第1年春季,果树行间分别种植不同草种,以不种草为对照,在7月高温干旱时研究种草后对苹果树光合作用的影响。结果表明:除百脉根(Lotus corniculatus)外,种其他草后苹果树叶片净光合速率(P_n)均显著提高(P<0.05);百脉根、多年生黑麦草(Lolium pe-renne)和匍匐翦股颖(Agrostis stolonifera)对苹果树叶片蒸腾速率(T_r)无显著影响,而种其他草种后苹果树的Tr显著高于对照(P<0.05);种大部分草后使苹果树叶片气孔导度(G_s)显著升高(P<0.05);种狗牙根(Cynodon dactylon)后,会使苹果树叶片胞间二氧化碳浓度(C_i)显著升高(P<0.05),其余种草处理均对苹果树Ci无显著影响;种草后,苹果树的水分利用效率(WUE)由高到低的顺序依次为:白三叶(Trifolium repens)>匍匐翦股颖>马蹄金(Dichondra repens)>草地早熟禾(Poa pratensis)>多年生黑麦草>狗牙根>草地早熟禾+多年生黑麦草>高羊茅(Festuca arundinacea)+草地早熟禾>红三叶(Trifolium pratense)=百脉根>紫羊茅(Festuca rubra)>对照,但只有50%与对照达显著差异(P<0.05)。说明果园种草后对苹果树光合特性的影响及程度与所生草种及其组合的不同有关,草种的选择是提高果园生草效益的重要环节。     

Climate Change in Western US Deserts: Potential for Increased Wildfire and Invasive Annual Grasses

Anthropogenic climate change is hypothesized to modify the spread of invasive annual grasses across the deserts of the western United States. The influence of climate change on future invasions depends on both climate suitability that defines a potential species range and the mechanisms that facilitate invasions and contractions. A suite of downscaled climate projections for the mid–21st century was used to examine changes in physically based mechanisms, including critical physiological temperature thresholds, the timing and availability of moisture, and the potential for large wildfires. Results suggest widespread changes in 1) the length of the freeze-free season that may favor cold-intolerant annual grasses, 2) changes in the frequency of wet winters that may alter the potential for establishment of invasive annual grasses, and 3) an earlier onset of fire season and a lengthening of the window during which conditions are conducive to fire ignition and growth furthering the fire-invasive feedback loop. We propose that a coupled approach combining bioclimatic envelope modeling with mechanistic modeling targeted to a given species can help land managers identify locations and species that pose the highest level of overall risk of conversion associated with the multiple stressors of climate change.     

遮荫对高羊茅和沿阶草生活力及抗氧化酶体系的影响

在夏季强光照条件下,通过对高羊茅(Festuca arundinacea Schreb.)和沿阶草(Ophiopogon japonicus(L.f.)Ker-Gawl.)进行遮荫处理后测定其生活力及抗氧化酶体系中主要酶的活性,研究遮荫对不同耐荫性草坪地被植物生理生化过程的影响。试验发现:78%遮荫处理对高羊茅和沿阶草都会造成胁迫,高羊茅受害更明显,生活力显著下降,酶系统活力降低,质膜受损;41%遮荫处理对高羊茅不会造成明显伤害,对沿阶草则是适合的生长条件,生活力、酶系统活力有显著提高。研究结果表明:遮荫胁迫下不同耐荫性草坪地被植物体内抗氧化酶活性变化有较大差异,且直接影响到植株的生活力;抗氧化酶活性与植物耐荫性可能关系密切,不同耐荫性草坪地被植物可能存在不同的抗氧化机制。     

干旱胁迫对冷地型草坪草生理特性影响的研究

研究了Fylking草地早熟禾(Poapratensis)、Target多年生黑麦草(Loliumperenne)、Cindy紫羊茅(Festucarubra)的幼茎和幼根在不同的干旱条件下超氧化物酶(SOD)、过氧化物酶(POD)的酶活性生理指标变化。试验结果发现,随着干旱程度的加剧,草坪草体内可溶性蛋白质含量呈现逐步增多的趋势;在同等干旱条件下,根系中的可溶性蛋白质增加量大于茎叶中可溶性蛋白质的增加量;可溶性蛋白质含量及SOD、POD在草坪草受干旱胁迫时,能清除体内过量的活性氧,维持代谢平衡从而使草坪草在一定程度上忍受、减缓或抵抗不良环境的胁迫;草坪草幼苗的不同器官对干旱胁迫的反应不同,幼茎的耐脱水能力大于幼根;通过试验发现,SOD和POD酶活性可作为鉴定草坪草品种抗旱性大小的重要生理指标之一。     

Long-Term Vegetation Recovery and Invasive Annual Suppression in Native and Introduced Postfire Seeding Treatments

Seed mixes used for postfire seeding in the Great Basin are often selected on the basis of short-term rehabilitation objectives, such as ability to rapidly establish and suppress invasive exotic annuals (e.g., cheatgrass, Bromus tectorum L.). Longer-term considerations are also important, including whether seeded plants persist, continue to suppress invasives, and promote recovery of desired vegetation. To better understand long-term effects of postfire seed mixes, we revisited study sites in Tintic Valley, Utah, where seeding experiments had been initiated after the 1999 Railroad wildfire. Four different mixes, including two comprised entirely of native species, had been applied using rangeland drills at a shrubland site and aerial seeding followed by one-way Ely chaining at a woodland site. New vegetation data collected 16 years post fire revealed changes relative to 3 years post fire. We found significant increases in total cover of seed-mix species in all treatments, including the unseeded control where these species were present as residual populations or had spread from seeded treatments. Significant increases of seed-mix species cover and density were observed in blocks where seeding treatments had previously been considered unsuccessful. Some seed-mix species, particularly rhizomatous grasses, increased while others declined. Exotic annual forb cover decreased in all treatments while cheatgrass increased in the unseeded control and to a lesser extent in the native-only seeded treatments. Recruitment of non-seed-mix native perennials was highest in the unseeded control. Results indicate that postfire seeding has lasting effects on vegetation composition and structure, implying that seed mixes should be carefully formulated to promote long-term management objectives. Seed mixes containing large amounts of competitive introduced species may be especially effective for long-term cheatgrass suppression, but native-only mixes can also serve this purpose to a lesser degree while avoiding drawbacks of non-native species introductions.     

利用RAPD技术分析内蒙古中东部草原三种针茅的遗传关系

利用RAPD分子标记技术对14份来自内蒙古中东部草原的贝加尔针茅(Stipa baicalensis Roshev.)、大针茅(S.grandis P.Smirn.)和克氏针茅(S.krylovii Roshev.)进行遗传多态性分析。筛选出16个引物,扩增出223条DNA片段,其中多态性片段为184条,多态性比率为82.51%。结果表明:14份材料呈现出明显的种间相似性,同一种针茅首先聚在一起;每一种针茅都获得了其特有的RAPD条带。     

秦岭野生苔草植物资源及坪用价值

苔草属植物是我国广泛分布的一种植物资源,一直作为牧草使用,但有些种类的苔草属植物也是优良的草坪草。陕西秦岭作为我国重要的植物资源基地,其苔草属植物的种类也很丰富。调查发现,陕西秦岭山区野生苔草属植物资源有40种,并对引进的20个种的苔草进行分类和坪用价值评价。结果表明,其中硬果苔草（Carex sclerocarpa）、青绿苔草（C.brevriculmis）、宜昌苔草（C.ascocetra）和云雾苔草（C.nubigena）的坪用价值较高,适宜作草坪植物。