混播草地不同种群再生性的研究

在不同刈割频率和时间尺度下 ,对混播草地多年生黑麦草 (Lolium perenne)分蘖数和叶片生长、白三叶 (Trifoliumrepens)分枝数和匍匐茎生长及不同种群年产量和组分进行了连续 3年的监测研究 .结果表明 ,刈割能刺激黑麦草叶片、白三叶匍匐茎生长和分枝数发生 ,保持混播草地黑麦草和白三叶的适宜比和稳定共存 ,提高草地年生产力 ,但不同刈割频率和刈割时间对其影响差异不显著 (P >0 .0 5 ) .黑麦草叶片生长对 6月刈割效果比 8月明显 ,而白三叶匍匐茎生长则与之相反 ,黑麦草产量主要取决于叶片生长 ,白三叶产量主要取决于匍匐茎分枝数 .刈割的黑麦草、白三叶产量组分比分别为 5 0 %、15 % ,比试验前约低 10 %、5 % ,而CK为 39%、6 % .     

气候因子和非气候因子对白三叶草叶片生长的影响

本文采用裂区试验设计,研究了刈割频率（强度）和品种对永久性混播草地组分白三叶草叶片生长的影响,并通过回归分析探讨了气候因子与白三叶草叶片生长的相关性。刈割对叶片出生率和每个葡萄茎现存叶片数的处理效应具季节依赖性特性,在夏季生长期,高频率刈割 处理。三叶草品种对叶片出生率和每葡萄茎观存叶片数均无显著的处理效应,但刈割与品种对秋初生长期叶片的出生率有显著的互作效应,对秋季生长期每葡萄茎现存叶片数有微弱     

刈割留茬高度和不同播种组合对人工草地初级生产力和物种丰富度的影响

采用7种播种方式(3种单播和4种混播)和3种刈割留茬高度裂区试验,测定了青藏高原高寒地区人工建植3年的垂穗披碱草(Elymus nutans)、中华羊茅(Festuca sinensis)和羊茅(Festuca ovina)草地地上生物量、物种丰富度以及杂草生物量,以分析刈割对青藏高原人工草地初级生产力和物种丰富度的影响。结果显示:(1)在草地建植第2年,不刈割与刈割留茬60和20 mm的草地初级生产力均有显著差异;留茬60和20 mm刈割使单播草地的平均初级生产力分别降低20%和27%,使混播草地的平均初级生产力分别降低29%和37%。(2)草地建植第3年,不刈割、留茬60和20 mm 3个处理间的草地生产力均差异极显著;留茬60和20 mm刈割使单播草地的平均生产力分别降低19%和36%,使混播草地的平均生产力分别降低4%和18%。研究表明,刈割显著降低了人工草地的初级生产力,同时显著增加了垂穗披碱草单播草地的物种丰富度和杂草生物量以及3种牧草混播草地物种丰富度,其他播种草地的物种丰富度和杂草生物量与不刈割草地均无显著差异。     

刈割后黑麦草生理保护作用对其补偿性生长的影响

通过对黑麦草(Lolium perenne L)在轻度、中度、重度、全割刈割处理6 d和12 d后,残留叶片和叶片再生部分生长速率,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活力,丙二醛、可溶性糖、脯氨酸含量的分析以揭示在刈割胁迫后叶片抗氧护酶活力和渗透调节物含量与其补偿性生长的关系,以及牧草耐刈性的生理调控机理。结果表明,轻度和中度及全割后叶片生长速率均高于对照,重度刈割低于对照。全割后叶片补偿性生长最明显、轻度和中度次之,重度刈割无补偿性生长。对照黑麦草叶片各部位抗氧化酶和渗透调节物含量不同,叶片顶部MDA含量较高,伴随着较高的SOD、CAT活力和较高的脯氨酸含量;叶片基部MDA含量最低,SOD、CAT活力及脯氨酸含量也较低。与对照相比,不同强度刈割6 d黑麦草再生叶和叶片平均MDA含量、SOD和CAT活力、可溶性糖和脯氨酸含量均较低。而不同强度刈割12 d,黑麦草再生叶和叶片平均MDA含量仍较低,但SOD和CAT活力增高,脯氨酸含量增加,POD活力和可溶性糖含量低于对照。这表明刈割在减少了叶面积,降低光合能力的同时,刈割伤害胁迫启动了牧草补偿性生长使残留叶片快速生长,而且残留叶片面积与其补偿生长速率成正相关。另外,虽然不同强度刈割下叶片补偿性生长速率不同,但不同强度刈割(12 d)均激活残留叶片抗氧化保护酶系统和促进脯氨酸积累。在补偿生长过程中,CAT和SOD能及时清除残留叶片中积累的氧自由基,维持较低的膜脂过氧化和细胞膜完整性,积累的脯氨酸能维护细胞水分平衡。因此,抗氧化酶(SOD和CAT)和渗透调节物(脯氨酸)在黑麦草刈割后受伤部位快速自愈及残留叶片快速补偿生长中起重要生理保护作用。     

一年生和多年生豆禾混播草地超产与多样性效应的比较

为了测度一年生和多年生豆禾混播草地的超产效应与植物多样性效应的关系, 明确一年生和多年生混播草地的高产优势, 探索豆禾混播草地多样性效应和超产效应对其生态功能的响应机制, 于2013-2015年在新疆伊犁地区昭苏盆地开展了3年的牧草产量观测试验。该试验设置3种牧草混播种类和混播比例, 分别为一年生豆禾混播草地(2种牧草混播, AM2)和多年生豆禾混播草地(2种牧草混播, PM2; 4种牧草混播, PM4; 6种牧草混播, PM6), 豆禾混播比例分别为6:4、5:5和4:6。结果表明: 1) 2013、2014年和3年平均值AM2的超产幅度小于PM2和PM6, 2015年AM2的超产幅度大于PM2、PM4和PM6; 混播群落生产力与群落组分中生产力最高产物种单产以及各组分种平均单产的差值表现出相似的规律。2) 2013、2014年和3年平均值AM2的互补效应大于PM2、PM4和PM6, AM2的选择效应则远小于互补效应, PM2、PM4和PM6的互补效应则比较稳定。3)物种丰富度和物种均匀度与牧草产量(群落生产力)大部分情况下呈单峰的“饱和上升型”模式, 分别在4种牧草混播和豆禾混播比例为5:5时, 具有较高生产力。4)多年生豆禾混播草地的互补效应、选择效应和多样性净效应均随生长年限的延长而呈下降趋势, 也导致了超产幅度、超产效应及其稳定性的下降。由此可见, 在建植初期, 互补效应和选择效应共同主导了多年生豆禾混播草地的超产效应, 而随着生长年限的延长, 选择效应则成为主要影响因素; 一年生豆禾混播草地的超产效应则一直受互补效应的影响。     

施肥和刈割对冷地早熟禾补偿生长的影响

以青藏高原东部高寒草甸常见牧草冷地早熟禾(Poa crymophila)为研究对象,比较研究了肥力和不同刈割处理对植物生长和生物量补偿的影响。实验采用随机设计,肥力分为施肥和不施肥,刈割处理为刈割时间、刈割频度和刈割强度3因子组合。结果表明:不刈割情况下,施肥显著促进冷地早熟禾的生长,而在刈割情况下,施肥对植物的生长没有明显的促进作用甚至有负作用。不施肥,刈割可促进冷地早熟禾地上生物量的增加并发生超补偿,但补偿程度因刈割强度、刈割频度和刈割时间而异;施肥时,刈割没有或很少促进植株发生超补偿。超补偿发生时,资源贫瘠的条件可能是必需的。冷地早熟禾发生超补偿可能是以损耗地下部分的资源为代价的,刈割刺激分蘖的增加对超补偿的发生也有一定的贡献。     

春小麦对刈割伤害的补偿作用研究

通过１９９５年大田试验研究了黄土高原半干旱区春小麦受刈割伤害（模拟动物采食）后的补偿作用。结果表明,在大田实验条件下,刈割处理一般会使小麦生长受阻且减产,即不足补偿。在刈割一半叶片的处理中,拔节期的减产效应重于苗期的减产效应;在苗期处理中,重度伤害（刈割全部叶片的减产效应大于轻度刈割（刈割一半叶片）的减产效应,而拔节期刈割前三位叶片的处理不仅未造成减产,还出现产量的超越补偿,是由于此时小麦早期生长     

小型无脊椎动物对混播草地白三叶叶片伤害程度研究

采用非破坏性的田间观测方法,以主匍匐茎的叶片伤害数,叶片伤害率和叶片伤害程度3个变量为指标,综合评价了小型无脊椎动物对多年生黑麦草与白三叶的混播草地白三叶叶片的伤害程度,系统探讨了白三叶品种类型（Alice,Retor和Gwenda),刈割频率（高与低）及草地特征（如三叶含量,地上生物量和草层高度）对小型无脊椎动物对叶片伤害的影响。研究表明,高频率刈割的草地白三叶叶片总的伤害数及中等程度伤害的叶片数明显地高于低频率刈割处理（分别为21％和35％）,另外,研究期总的叶片伤害数不同程度伤害的叶片数因白三叶品种的不同而存在着很大差异,且这种差异在春季,夏末和秋季等3个时期均十分明显,在这3个时期,在两种频率刈割下,均是品种Retor的叶片伤害数和叶片伤害率明显高于品种Alice和Gwenda,研究还表明,叶片的伤害与白三叶种群特征如白三叶含量和地上生物量存在显著的负相关,白三叶含量和地上生物量越低,则叶片的伤害数和伤害率就越高,回归模型显示,白三叶含量和地上生物量可以解释叶片的伤害数在春季,夏末,秋季各65％,59％和50％的变异,可以解释叶片伤害率在这3个时期各58％,57％和45％。     

5种入侵植物补偿反应及其形态可塑性比较

通过模拟刈割试验,研究了5种外来入侵植物(黑麦草、空心莲子草、三叶鬼针草、薇甘菊和胜红蓟)的补偿能力及其形态可塑性。结果表明:多数植物的补偿能力与形态可塑性有一定相关性,刈割和非刈割条件下空心莲子草和薇甘菊都具有较强的形态可塑性,其补偿指数较高,分别为1.65和1.27;多年生黑麦草和三叶鬼针草的形态可塑性在刈割条件下得到增强,补偿指数分别为1.44和1.28;刈割条件下胜红蓟的形态可塑性变化不大或有所降低,其补偿指数最低,为0.82。研究认为,5种植物具有不同的限制其形态可塑性和补偿能力比较理想的刈割时期,薇甘菊攀援生长方式下为30d前和60d后,空心莲子草为60d后,胜红蓟为40～50d,鬼针草为30d前,黑麦草为40～50d。     

苗期刈割伤害对春小麦生长及产量的影响

通过1996年大田试验研究了黄土高原半干旱区春小麦苗期（三叶－心期）受到不同强度刈割伤害（模拟动物的采食）后的补偿作用,结果,在大田试验条件下,受轻度刈割（刈割一半叶面积,H0,H1）,春小麦的补偿效应大于受重度刈割（刈割全部叶面积T0,T1）春小麦的补偿效应,且都低于未受刈割处理（对照,CK0,CK1）,即CK0＞H0＞T0;CK1＞H1＞T1,刈割处理后,灌溉一次水（CK1,H1,T1）虽可增强其补偿能力,促进小麦的生长,但仍为低补偿。     

Effect of Cutting on Production and Tillering in Prairie Grass (Bromus willdenowii Kunth) Compared With Two Ryegrass (Lolium) species. 2. Reproductive Plants

Effects of time of initial cut and subsequent cutting interval(1, 2 or 4 weeks) were examined in a glasshouse during summer1988 for reproductive plants of three prairie grass cultivars(Bromus willdenowii Kunth), Westerwolds ryegrass (Lolium multiflorumLam.) and perennial ryegrass (Lolium perenne L.). Measurementswere made of tiller and leaf numbers, sites of tillering, reproductivedevelopment, and herbage quality and yields. Effect of timeof initial cutting on regrowth appeared to be independent ofstage of reproductive development and unrelated to any of themeasured plant parameters. Characteristics for each cultivaras identified during undisturbed growth prior to the initialcuts, were modified by the subsequent cutting frequencies. Perennial ryegrass had the highest yields under frequent cuttingwith high herbage quality. Westenwolds ryegrass and the prairiegrass cultivars ‘Grasslands Matua’ and ‘Primabel’had the highest yields with infrequent cutting, but lower herbagequality than in perennial ryegrass. At each cut, tiller deathin prairie grass was determined by the number of reproductivetillers, and in the ryegrasses also by the numbers of elongatedvegetative tillers. Recovery of tiller numbers was rapid andprimarily from inhibited tiller buds at the base of reproductivetillers. In prairie grass, tiller numbers were relatively unaffectedby cutting frequency, but at frequent cutting, many axillarytillers originated from vegetative tillers rather than frominhibited tiller buds at the base of reproductive tillers. Prairie grass, Bromus willdenowii Kunth, Westerwolds ryegrass, Lolium multiflorum Lam., perennial ryegrass, Lolium perenne L., first (initial) cut, cutting frequency, regrowth, leaf appearance, tillering, yield, nitrogen, water-soluble carbohydrates, herbage quality     

Leaf and Tiller Production of Prairie Grass (Bromus willdenowii Kunth) and Two Ryegrass (Lolium) Species

A detailed morphological study of three prairie grass cultivars(Bromus willdenowii Kunth) was conducted under ‘vegetative’and ‘reproductive’ growth conditions (short andlong photoperiods) and at different temperatures. Perennialryegrass (Lolium perenne L.) and Westerwolds ryegrass (Loliummuhiflorum Lam.) were compared during vegetative growth. Prairie grass had higher leaf appearance rates (leaves per tillerper day) and lower site filling (tillers per tiller per leafappearance interval) than the ryegrass species. Tillering rates(tillers per tiller per day) were also lower, except under vegetativeconditions at 4C. Low tiller number in prairie grass was notdue to lack of tiller sites but a result of poor filling ofthese sites. Lower site filling occurred because of increaseddelays in appearance of the youngest axillary tiller and lackof axillary tillers emerging from basal tiller buds. In prairiegrass, no tillers came from coleoptile buds while only occasionallydid prophyll buds develop tillers. Low tiller number in prairiegrass was compensated for by greater tiller weight. Prairiegrass had more live leaves per tiller, greater area per leafand a high leaf area per plant. Considerable variation between cultivars was found in prairiegrass. The cultivar ‘Bellegarde’ had high leaf appearance,large leaves and rapid reproductive development, but had lowlevels of site filling, tillering rate, final tiller numberand herbage quality during reproductive growth. ‘Primabel’tended to have the opposite levels for these parameters, while‘Grasslands Matua’ was intermediate and possiblyprovided the best balance of all plant parameters. prairie grass, Bromus willdenowii Kunth, perennial ryegrass, Lolium perenne L., Westerwolds ryegrass, Lolium multiflorum Lam., temperature, photoperiod, leaf appearance, leaf area, tillering, site filling, tillering sites, yield     

Tillering Potential and Relationship Between Leaf and Tiller Production in Perennial Ryegrass

A detailed morphological examination of the tillering characteristicsof perennial ryegrass (Loltum perenne L.) is presented. It isshown that the tillering potential of perennial ryegrass interms of site filling is 0–693 tillers/tiller/leaf appearanceinterval. This is higher than earlier presented values and isdue to the tillering ability of the prophyll bud which has notpreviously been taken into account. In a controlled climateroom experiment with spaced plants of perennial ryegrass, meanvalues of site filling were found to be close to this theoreticalmaximum Due to growth-limiting factors, tiller formation from leaf axillarybuds can be delayed or suppressed entirely. A set of equationsis presented from which site filling and the ratio of new leavesto new tillers can be calculated for all situations of axillarybud activity. It is stressed that leaf appearance rate can onlybe determined by marking and counting leaves on single tillersat consecutive dates Loltum perenne (L.), perennial ryegrass, tillering, axillary bud, leaf appearance rate, prophyll, site filling     

Leaf photosynthesis in pure swards of two grasses (Lolium perenne and Lolium multiflorum) subjected to contrasting intensities of defoliation

Photosynthetic rates were measured on light saturated, fully-expanded leaves in pure swards of Lolium perenne and Lolium multiflorum during late summer using 14-carbon dioxide. These swards were defoliated by cutting at three heights of 3, 6 and 9 cm above the ground. The photosynthetic rates of leaves on tillers in swards cut constantly 3 cm above ground level were higher than those of leaves in swards cut constantly 9 cm above ground level. Additional treatments with various sequences of cuts 3, 6 and 9 cm above ground level were designed to reduce damage to the growing points of tillers whilst ensuring satisfactory harvesting of the shoots. The photosynthetic rates of leaves on tillers cut to various heights above ground level at successive harvests were intermediate between those of similar leaves in the constantly low and high cut swards. The rates of photosynthesis of Italian ryegrass leaves were higher than those of perennial ryegrass leaves for a short time after defoliation of the constantly high cut swards. However, these perennial ryegrass leaves quickly adapted their rates of photosynthesis to the higher irradiances they received after cutting. Thus grass species differing in morphology adjust to management practices by the use of different photosynthetic strategies.     

多年生黑麦草草地生态系统中放牧强度对草地结构及组织转化的影响

研究了放牧强度对多年生黑麦草人工草地蘖的形态、密度、草地生产率及组织转化的影响。结果表明,重牧条件下蘖密度大于轻牧,而轻牧的单株蘖重大于重牧。重牧划地净生产率大于轻牧,主要是由于轻和手条件下,草地的高的生长率被更高的枯死率所抵消。春夏之交,采用灵活的管理措施,转换放牧强度可以提高草地的生产率。     

Effect of Cutting on Production and Tillering in Prairie Grass (Bromus willdenowii Kunth) Compared With Two Ryegrass (Loliunt) Species. 1. Vegetative Plants

Effects of cutting to 3 or 6 cm stubble height at frequenciesof 1, 2 or 4 weeks were investigated in young, vegetative, spacedplants of prairie grass (Bromus willdenowii Kunth), a tetraploidWesterwolds ryegrass (Lolium multiflorum Lam.) and perennialryegrass (Lolium perenne L.). Plants were grown for 8 weekson nutrient solution in a growth cabinet at day/night temperaturesof 15/10°C and in a short photoperiod. Leaf appearance,site filling and tiller numbers were all reduced by both increasedcutting frequency and a lower cutting height. The extent ofthese reductions was least in prairie grass and greatest inWesterwolds ryegrass. Relative growth rates in all species respondedin a similar manner with more frequent cutting and a lower cuttingheight. Cutting frequency had the greatest effect on growthrates, although the effect of cutting height increased withtime. Results confirm general recommendations of long intervalsbetween defoliations to achieve high yields for vegetative prairiegrass, but the relative amounts of dry matter harvested underthe different cutting regimes may be no different to that obtainedin ryegrass. Stubble height was of lesser importance in determiningyields. A typical U-shaped curve for depletion and recovery in water-solublecarbohydrates occurred after defoliation in all species, butlevels remained low at frequent cutting. Water-soluble carbohydratelevels in stubble and roots were higher in prairie grass. Regrowthat the end of the experiment was highly correlated with totalstubble and root weights (r = 0.84), while regrowth per tillershowed a good correlation with water-soluble carbohydrate content,although the response varied between species. Prairie grass, Bromus willdenowii Kunth, perennial ryegrass, Lolium perenne L., Westerwolds ryegrass, Lolium multiflorum Lam., cutting frequency, cutting height, leaf appearance, tillering, site filling, yield, regrowth, nitrogen, water-soluble carbohydrates     

GROWTH AND NUTRITION OF TIMOTHY (PHLEUM PRATENSE)

Individual tillers of timothy ( Phleum pratense ) growing from seed in pots were labelled and their life history studied over a period of two years.
The leaf axil position of the first-produced tiller depended on its time of origin. A minimum of five leaves on the parent axis was necessary before its appearance, and no tiller emerged from the axil of any of the three terminal leaves of a shoot.
Ear-bearing capacity was high in early-formed tillers, but decreased progressively with later dates of origin despite favourable day length; all tillers arising after the end of July failed to produce inflorescences. A greater proportion of tillers on the main stem formed ears than secondary tillers of the same age. Time of ear emergence varied only within a few days for all tillers arising before the end of April. The number of leaves formed up to ear emergence varied linearly with date of origin and tiller position, the lowest recorded number being six.
Dry weight and length of inflorescence as well as seed yield per tiller varied linearly with the date of origin of tillers. Primary tillers generally had longer and heavier inflorescences and produced more seed per stem than secondary tillers of the same age.
Tillers arising at all times were found to have a limited span of life, not normally exceeding just over a year. The mean age of ear-bearing tillers varied linearly with their date of origin. Death-rates of all tillers generally increased with their age. Relative death-rates of fertile and vegetative tillers rose rapidly in the autumn but decreased during winter and early spring. Vegetative tillers which elongated in the year of formation survived for a shorter time than equivalent tillers in which stem elongation was delayed until the following year.
The perennial habit of grasses is discussed in relation to tiller survival. Successive new formation and death of tillers keep the plant in a condition of continuous dynamic change.     

Rates of Leaf and Tiller Production in Young Spaced Perennial Ryegrass Plants in Relation to Soil Temperature and Solar Radiation

In an experiment designed to investigate the rate of leaf appearanceand tiller production in young spaced plants of three clonesof perennial ryegrass grown in the field, it was found thatthe rate of leaf appearance per tiller increased linearly withmean soil temperature up to approx. 14 °C. The rate of productionof tillers in relation to the rate of leaf appearance (sitefilling) appeared to be virtually independent of weather conditions.In plants which were adequately established, but still relativelysmall, site filling was equal to or exceeded the theoreticalsteady state; all the tiller buds which were being formed weredeveloping into visible tillers. Thus the relative rate of tillerproduction was controlled by the rate of leaf appearance. Inlarger plants site filling was less complete, and site redundancieswere probably caused by within-plant competition for light atthe tiller bases. Lolium perenne L., perennial ryegrass, tillering, leaf production, solar radiation, soil temperature     

Effects of plant growth regulators on tiller bud outgrowth in uniculm cereals

Plant growth regulators were applied either to seeds or to leaves of uniculm selections of barley and wheat. None of the treatments stimulated the growth and development of tiller buds in the barley selection. In contrast, in wheat the development of tiller buds was readily stimulated and tillers were produced following treatment with Terpal, Cerone, TIBA or nitrate. In Terpal and Cerone treated plants, the stimulation of tiller bud outgrowth and tillering was accompanied by a marked retardation of growth in the main shoot. The growth of the tillers was however not sustained in any of the treatments, and so at maturity all plants were virtually uniculm. The results are discussed in relation to the different overall response of the two species, the death of tillers, and the hormonal regulation of tiller bud development.