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。     

草地早熟禾无融合生殖现象的研究

本文应用石蜡切片和子房整体染色透明法研究了草地早熟禾(Poa pratensisL.)的无融合生殖现象,结果表明,草地早熟禾的胚胎发育分为两种类型。一种是由孤雌生殖形成胚,即卵细胞分裂较早形成幼胚,少数胚囊中的一个或两个助细胞也分裂较早,同时形成幼胚,但两个极核并不融合,三个反足细胞明显增大。由孤雌生殖形成胚的约占观察总数的66%,其中3%为双胚,仅一个是三胚。在成熟种子中也有两个成熟胚并生的现象。另一种是形成胚和胚乳,约占34%。34%中形成种子有两种可能的途径,一是通过有性生殖形成种子,二是由孤雌生殖形成的胚和极核受精形成的胚乳共同组成的无融合生殖种子。本研究还首次观察到早熟禾完整的双胚囊结构。     

北京地区野生草地早熟禾引种驯化研究

通过对野生草地早熟禾在黄土及沙壤土上的引种驯化研究。结果表明：野生草地早熟禾在试验地能够完成出苗、分蘖、拔节、抽穗、开花、种子成熟等年生育周期,年生长期241天;能通过播种及分株方法繁殖;具有较强的耐寒性及耐高温性;能够在黄土、沙壤土上正常生长。刈割处理能够显著提高野生草地早熟禾产量。草地早熟未是北京地区畜牧业及园林绿化中优良的野生乡土草种。     

草地早熟禾胚胎学研究 Ⅲ．多胚囊及多胚现象

报道了草地早熟禾中多胚囊的起源、发育和结构。在１个胚珠中,大孢子母细胞周围可以有一到多个起源于珠心细胞的胚囊原始细胞,并可以发育成为多胚囊,其中具有两个胚囊的可以发育成为成熟胚囊。起源于珠心的体细胞无孢子生殖胚囊的发育属于山柳菊型。两个成熟胚囊中,都可以形成胚和胚乳,因而形成了具假多胚的种子。位于中部的胚来源于珠心还囊,属于无融合生殖形成的胚。两个以上的多胚囊不能形成成熟胚囊。     

雾灵山草地早熟禾多胚囊和多胚现象的研究

无融合生殖是指未经精卵融合而产生后代的特殊生殖方式,它可以分为单倍体无融合生殖和二倍体无融合生殖;对于作物改良意义更大的是二倍体无融合生殖。多胚囊和多胚现象SHI是无融合生殖的表现形式。本文运用石蜡切片法、子房整体透明法研究了雾灵山草地早熟禾〖WTBX〗（Poa pratensis〖WTBZ〗 L.）多胚囊和多胚现象。结果表明,（1）草地早熟禾多胚囊来源有两种：一是来自大孢子母细胞,二是来自珠心细胞;（2）草地早熟禾多胚来源有四个：其一是有性生殖胚,其二是孤雌生殖胚,其三是无配子生殖胚,其四是珠心胚。     

雾灵山草地早熟禾多胚囊和多胚的研究

无融合生殖是指未经炷卵事例而产生后代的特殊生殖方式,它可以分为单倍体无融合生殖和二倍体无融合生殖;对于作物意义更大的是二倍体无融合生殖。多胚囊和多胚现象ＳＨＩ是无融合生殖的表现形式。本文运用石蜡切片法、子房整体透明法研究了雾灵山草地早熟禾（Ｐｏａ ｐｒａｔｅｎｓｉｓ Ｌ．）多胚囊和多胚现象。结果表明,（１）草地早熟禾多胚囊来源有两种：一是自大孢子母细胞,二是来自珠心细胞;（２）草地早熟禾多 来源有     

草地早熟禾草坪土壤水分动态与根系生长分布

对草地早熟禾草坪土壤水分动态和根系生长发育状况进行研究,结果发现不同土壤层次水分变化有所不同,0～15cm变化最大,15～30cm次之,30cm以下土层水分变化不大;草地早熟禾的根系生长呈现双峰曲线模式,5月中旬和8月中下旬总根量处于峰值;其主体根系主要分布在0～30cm土层内,占总根量的85%以上;根重密度随土层深度呈指数衰减关系,0～30cm土层下降幅度较大,30cm以下土层根重密度相差不大;在0～30cm土层内不同层次根量占总根量的比例在不同时期亦有差异,春秋季节10～20cm和20～30cm土层内根量比例较大,说明此时期主体根系分布在较深的土层;综合分析认为草地早熟禾草坪主要利用土壤浅层水分,在降雨较少的春秋季节,根系较深,适宜深层灌溉,在降雨频繁的夏季,根系较浅,适宜浅层灌溉。     

影响草地早熟禾（Poa pratensis L.）基因枪转化关键因素研究

将含有DREB1A基因的表达载体,通过基因枪法转化草地早熟禾的胚性愈伤组织,探讨了金粉沉淀剂、金粉直径等因素对转化的影响,同时通过不同浓度潮霉素（Hygromycin,简称Hy）对未转化愈伤组织的筛选,获得最佳筛选浓度。结果表明,适合于草地早熟禾基因枪轰击的条件为：Ca（NO3）2＋PEG4000包被质粒DNA;1μm金粉作为质粒DNA的载体;合适的轰击高度为6cm、轰击次数为1次、无渗透处理。采用Hy作为草地早熟禾转基因植株抗生素筛选标记时,Baron品种愈伤组织继代的临界筛选浓度为100mg/L。     

草地早熟禾悬浮体系的建立及悬浮过程中细胞形态观察

对早熟禾(Mardona)成熟种子灭菌后,接种于MS2 BA0.1诱导培养基,26℃,全黑暗培养诱导胚性愈伤,挑选其中松散的颗粒状胚性愈伤悬浮于MS2 BA0.1液体培养基中,在90~110r/min,26℃黑暗培养下,悬浮培养2个月,建立悬浮体系。在悬浮培养过程中,对细胞形态进行显微观察,发现悬浮培养前期,细胞多为条状、棒状,且大小不一。培养20天后,悬浮培养物开始增殖,2个月后,悬浮体系建立,细胞大小均匀,颜色嫩白。     

农杆菌介导的单子叶植物早熟禾的转化

利用种子和胚分别在两种培养基K3和K5诱导产生了早熟禾(Poa pratensis L.)一个品种Mado的胚性愈伤组织。K3培养基含有10.0μmol/L的二氯苯氧乙酸(2,4-D)、0.5μmol/L的苄氨基嘌呤(BAP)。K5培养基是K3另加0.5μmol/L的硫酸铜。光照条件为20～30μmol·m~(-2)·s~(-1)、16h光照、8h黑暗。温度保持在24℃。用携有bar基因和gus基因的pDM805质粒转化的农杆菌AGL1对胚性愈伤组织进行转化。共得到4个转基因株系。影响转基因效率的主要因素有愈伤组织的胚性、光照条件、共转化时间、抗生素浓度、选择压力。本研究建立了单子叶早熟禾农杆菌介导的转基因方案。     

农杆菌介导的单子叶植物早熟禾的转化

利用种子和胚分别在两种培养基K3和K5诱导产生了早熟禾(Poa pratensis L.)一个品种Mado的胚性愈伤组织.K3培养基含有10.0μmol/L的二氯苯氧乙酸(2,4-D)、0.5μmol/L的苄氨基嘌呤(BAP).K5培养基是K3另加0.5μmol/L的硫酸铜.光照条件为20～30 μmol.m-2.s、16 h光照、8 h黑暗.温度保持在24℃.用携有bar基因和gus基因的pDM805质粒转化的农杆菌AGL1对胚性愈伤组织进行转化.共得到4个转基因株系.影响转基因效率的主要因素有愈伤组织的胚性、光照条件、共转化时间、抗生素浓度、选择压力.本研究建立了单子叶早熟禾农杆菌介导的转基因方案.     

Effect of Tylenchorhynchus nudus on Growth of Kentucky Bluegrass

The effect of Tylenchorhynchus nudus on growth of Kentucky bluegrass was investigated under controlled environmental conditions in both a phytotron and a greenhouse. The nematode significantly reduced weights of clippings, crowns and roots. Pathogenicity was greater in sandy loam soil than in loam and was enhanced by submitting plants to nutrient and/or moisture stresses; soil nutrient level was most critical. The results suggest that T. nudus contributes significantly to summer decline of bluegrass lawns in South Dakota.     

Relationship between Cultural Factors and Nematodes on Merion Kentucky Bluegrass

A 2-year study was conducted on Merion Kentucky bluegrass turf (Poa pratensis) to identify potential relationships among seasonal population dynamics of nematodes, chemical applications, thatch, tillering, dollar spot caused by Sclerotinia homoeocarpa, clipping weight, and other factors. Numbers of Tylenchorhynchus maximus determined during June were inversely related to the wet weight of grass from May. One or more monthly counts of Paratylenchus hamatus, Criconemella rusium, and T. maximus negatively correlated with the numbers of spring tillers. Applications of benomyl, used for dollar spot control, decreased numbers of T. maximus and free-living nematodes, and this chemical was associated with acidification of the thatch. Hoplolaimus galeatus levels were associated with an estimated 8% increase in the severity of dollar spot.     

Preliminary Observations on Resistance to Rust Diseases of Kentucky Bluegrass Ecotypes from Poland

Four hundred and forty-four ecotypes of Kentucky bluegrass ( Poa pratensis L.) collected from Poland were screened for rust resistance. A field experiment was established at Hof Steimke, DSV (Deutschen Saatveredelung), Germany. The ecotypes originated from the Polish Gene Bank, IHAR – Botanical Garden, Bydgoszcz. Sixty-two (13.9%) ecotypes that scored on average more than 5 were included in a group with high resistance. Ecotypes scored on average less than 5 were either included in a susceptible group (average scores 4.0–4.9) or a very susceptible group (average scores 2.0–3.9). There were 181 ecotypes in the susceptible group (40.8%) and 201 (45.3%) in the very susceptible group. Thirty-three (7.4%) ecotypes were more resistant and 29 (6.5%) ecotypes had resistance on the level of the most resistant control variety Ottos (score of resistance 5.3). Eight ecotypes (1.8%) with the highest level of resistance (score 7 or higher) were identified as especially promising sources of rust resistance. One ecotype (141858) showed reaction type 9 in both years and another one (141903) showed reaction type 9 in one year and reaction type 8 in another year (mean 8.5). Six ecotypes were scored on average 7 or 7.5. For 17 different habitats from which the tested ecotypes were collected only those ecotypes originating from 10 habitats (meadow, peat meadow, forest meadow, pasture, field, lakeside, waterside, ditch, roadside and gravel pit) showed high levels of resistance to rust. The value of newly identified resistant ecotypes for control of rusts on Kentucky bluegrass is discussed.     

空间条件对草地早熟禾植株过氧化物同工酶和酯酶同工酶的影响

将草地早熟禾(Poa pratensis L.)巴润(baron)干种子分别进行蒸馏水和硼酸处理后利用返回式卫星搭载,以未搭载干种子作为对照.对不同处理植株过氧化物同工酶(POD)和酯酶同工酶(EST)酶谱进行分析.结果表明,空间条件处理引起部分草地早熟禾植株POD和EST的差异,在酶带位置、数量、强弱等方面与对照相比出现了一定的变化,说明空间条件作用后草地早熟禾种子后代植株产生了一定变异.     

Selection of Kentucky Bluegrass for Drechslera poae Resistance under Greenhouse Conditions

Resistance to leaf spot and melting out caused by Drechslera poae was evaluated in eight cultivars and seven breeding lines of Poa pratensis under greenhouse conditions. The results obtained in this study were compared with levels of resistance scored after natural infection under field conditions during 1994–1997 in sun and shade lawn maintenance, as described before. It was found that resistance assessed in the greenhouse as leaf spots in the three‐leaf seedling stage 10–14 days after the first inoculation (assessment I) and resistance assessed as severity of melting out on the crown 56 days after the first inoculation (assessment IV) showed the highest repeatability with the scores obtained in the field under sun and shade conditions during 1994–1997.     

Proteins and Metabolites Regulated by Trinexapac-ethyl in Relation to Drought Tolerance in Kentucky Bluegrass

Plants have developed various mechanisms in adaptation to water deficit stress, including growth retardant to reduce water loss. Previous studies reported that plants treated with a growth inhibitor, trinexapac-ethyl (TE), had improved drought tolerance. The objective of this study was to determine alterations in proteins and metabolite accumulation associated with drought tolerance improvement in a perennial grass species, Kentucky bluegrass (Poa pratensis), induced by TE application. Plants were treated with TE [1.95 ml l⁻¹ (v:v); a.i. TE = 0.113%] through foliar spray for 14 days, and then subjected to drought stress by withholding irrigation for 15 days in growth chambers. TE-treated plants exhibited significantly higher relative water content and photosynthetic capacity and lower membrane leakage than nontreated plants under drought stress, suggesting TE-enhanced drought tolerance in Kentucky bluegrass. Physiological improvement in drought tolerance through TE application was associated with the increased accumulation of various proteins and metabolites, including ferritin, catalase, glutathione-S-transferase, Rubisco, heat shock protein 70, and chaperonin 81, as well as fatty acids (palmitic acid, α-linolenic acid, linoleic acid, and octadecanoic acid). Our results suggest that TE may regulate metabolic processes for antioxidant defense, protective protein synthesis, photorespiration, and fatty acid synthesis, and thereby contribute to better drought tolerance in Kentucky bluegrass.     

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.