松嫩平原野大麦无性系分蘖株的年龄结构

野大麦无性系分蘖株由３个龄级组成,为明显的增长型年龄结构、１龄级蘖在无性系生殖生长中占绝对优势。分蘖株龄级越高,其数量增长速率越小,对无性系物质积累的贡献越小,１、２龄级分蘖株数量和生物量均随着无性系丛径和总蘖数的增加而增长,３龄级蘖与总蘖数间呈直线相关。平均单蘖生产力随着龄级增加而下降。生殖蘖平均单蘖重具有相对稳定性。无性系中１龄级蘖平均单蘖重体现出一定的密度调节作用,无性系潜在种群也为明显的增     

放牧对亚热带人工草地牧草构型及小格局的影响

对休牧后的亚热带人工草地及长期禁牧草地牧草种群的构型及小格局的研究结果表明。随着放牧强度的增加,鸭茅、红三叶株丛宽度逐渐变小．在对照及6只羊·hm^-2、7．5只羊·hm^-2、10只羊·hm^-2轮牧草地上,鸭茅基径的峰值分别介于6～8cm、2～4cm、0～2cm和0～2cm之间;红三叶则介于1～1．2cm、6～8cm、4～6cm和2～4cm之间;鸭茅丛密度分别为60、95．1、210．2和160丛·m^-1;单丛蘖数量分别为11．9、11．2、7．3、6．9蘖／丛．与禁牧草地相比,放牧草地鸭茅单丛蘖的数量明显减少,而丛密度则明显增加,白三叶节间长度因放牧强度增加而明显下降,为1．51～2．04cm,分枝角度则逐渐变大,介于46．5～77．3°,鸭茅、白三叶及红三叶在小格局水平上其格局规模均以1个样方(2cm×2cm)为主,并且随着放牧强度的提高,鸭茅、红三叶小格局规模进一步变小,白三叶构型及小格局的变化提高了牧草对环境资源的利用率。     

松嫩平原人工草地野大麦无性系构件的生物量结构及生产规律

野大麦属短根茎丛生型禾草,是典型的无性系植物．在松嫩平原生长季末期。野大麦无性系分株由抽茎的分蘖株和莲座状分蘖苗组成．按照分蘖节营养繁殖世代的龄级划分方法,建植2年人工草地野大麦无性系的分蘖株由3个龄级组成,分蘖苗由4个龄级组成,其生物量均呈增长型的龄级结构．在野大麦无性系的物质生产中,无论是分蘖株,还是分蘖苗,均以1龄级的单蘖生产力最高,并随着龄级的增高呈不同程度的下降．丛径是衡量野大麦无性系空间大小的重要数量指标．分株数量是衡量野大麦无性系生长的重要数量指标．经统计分析,野大麦无性系的分蘖株生物量、分蘖苗生物量、根茎生物量、总生物量分别与丛径和总分株数量之间均有极密切的正相关关系,其相关程度最佳的均为幂函数,其相关性均达到极显著水平(P<0．01)．这些相同的函数变化表明,随无性系的空间扩展和数量增长,各构件具有相同的物质生产与积累规律．     

松嫩平原贝加尔针茅无性系构件的结构及生长规律

采用整个分蘖丛挖掘的取样方法,对松嫩平原栽培条件下贝加尔针茅无性系构件的结构,以及生长与生产规律进行了定量分析.结果表明,在9月末停止生长期,经过2个生长季的营养繁殖,贝加尔针茅无性系的丛径为9.4±3.24 cm.无性系的全体构件数为161.±8.2个.其中,生殖分蘖株为14.6±11.48个,占9.2%;营养分蘖株为146.9±78.70个,占90.7%.全体构件总生物量为3.8±34.22 g,其中生殖分蘖株生物量为2.0±20.34 g,占43.7%;营养分蘖株为28.8±19.43 g,占6.2%.随着丛径的增加,不同构件的数量均具有线性同速生长规律,而不同构件的生物量均具有幂函数异速增长规律.不同构件生物量与无性系全体构件的数量和生物量之间均呈显著(P<0.0)或极显著(P<0.01)的幂函数正相关关系.平均单个生殖分蘖株的生产力约为营养分蘖株的10倍.生殖分蘖株的数量和生物量的表型可塑性普遍大于营养分蘖株.     

松嫩平原碱化草甸朝鲜碱茅无性系冬眠构件的结构及生长分析

采用大样本随机挖取单个无性系的调查和测定方法,分析了松嫩平原碱化草甸朝鲜碱茅无性系冬眠构件的结构及其生长规律。结果表明,在生长季末期,朝鲜碱茅无性系冬眠构件是由冬眠苗和冬眠芽组成,其中,冬眠苗平均为72.27个±48.29个,冬眠芽为45.87个±26.27个。朝鲜碱茅无性系冬眠构件各组分具有相同的形成规律。冬眠苗数、冬眠芽数、冬眠构件总数均随着丛径、丛面积和亲株数量的增加呈幂函数异速生长。     

松嫩平原碱化草甸朝鲜碱茅(Puccinellia chinampoensis)种群生殖分蘖株的生长规律

朝鲜碱茅(Puccinellia chinampoensis)是一种耐盐碱丛生型禾草,广泛分布于松嫩平原碱化草甸.采用每隔3d对朝鲜碱茅种群中处于抽穗初期的生殖分蘖株随机挂一次标签,于籽实蜡熟期同时进行大样本取样与测定的方法,定量分析了5次所标记的生殖分蘖株的数量性状的变化规律及生殖分蘖株的生长规律.结果表明,在朝鲜碱茅种群中,虽然抽穗时间只相隔3d,但生殖分蘖株的各数量性状均具有较大的表型可塑性,总的变化趋势是抽穗时间相隔越长,差异越大.其中,5次样本中的相邻平均花序生物量之间的差异均达到了显著水平.延长生殖生长16d,平均分蘖株高增加了23.16%,花序长增加了25.70%,分蘖株生物量增加了74.99%,花序生物量增加到2.63倍,生殖分配增加了93.25%.随着生殖生长时间的延长,朝鲜碱茅种群生殖分蘖株高、分蘖株生物量和花序生物量均呈指数增加,花序长和生殖分配呈直线增加,生殖生长比率呈先增加后降低的抛物线变化.不同时间进入生殖生长阶段的生殖分蘖株均具有相同的生长规律.其中,花序长均随分蘖株高的增加呈指数异速增长,花序生物量均随分蘖株生物量的增加呈直线同速增长.分蘖株的生殖生长越延长,对现实种群的贡献就越大,对未来种群的贡献更大.     

不同放牧率对大针茅种群结构的影响

 采用连续放牧的方式研究了不同放牧率对大针茅(Stipa grandis)种群结构的影响。研究结果表明：在一定放牧率范围内,单丛分蘖密度随着放牧率的增加而增加,超过这个范围,单丛分蘖密度下降;单位面积生殖枝数、结实数和种子重随放牧率的增加而下降,种子千粒重在轻度和中度放牧率下最大;不同年龄株丛的分蘖密度存在很大差异,老龄株丛的分蘖密度最大,其次是成年株丛,幼龄株丛最小;轻度和中度放牧率能够刺激成年和老龄株丛分蘖,增加其单丛分蘖密度;老龄株丛在种群的有性生殖中占有重要地位,其生殖枝数目高于成年株丛。     

松嫩平原人工草地野大麦无性系冬眠构件的结构及形成规律

野大麦属短根茎丛生型禾草 ,是典型的无性系植物。在松嫩平原 ,野大麦无性系的冬眠构件是由冬眠芽和冬眠苗组成。按照分蘖节营养繁殖世代的龄级划分方法 ,在生长季末期 ,野大麦无性系的芽库由 5个龄级组成 ,苗库由 4个龄级组成 ,均呈增长型的龄级结构。苗库对潜在无性系的贡献将远远大于芽库。结合建植时间估计 ,人工草地野大麦的分蘖节最多存活了两个年度 ,分蘖节在一个生长季最多可繁殖 4个世代。野大麦无性系的根茎芽数、分蘖节芽数、总芽数、总苗数、总冬眠构件数均随着丛径、丛面积和亲株数量的增加呈幂函数形式增长。野大麦无性系冬眠构件各组分具有相同的形成规律 ,但在形成过程中则存在着不同的生态可塑性。     

松嫩平原碱化草甸星星草种群营养繁殖及有性生殖的数量特征

根据对星星草单优群落独立株丛的大样本取样和对正常花序随机取样的调查与测定,分析了松嫩平原碱化草甸星星草种群的营养繁殖及有性生殖特征．结果表明,星星草种群诸营养繁殖数量性状之间有明显的规律性,丛植株数、丛地上生物量、丛生殖株数及丛生殖株重分别随丛径呈指数形式增加．星星草种群的圆锥花序大多为９—１６个节,花序上各节位上的小穗数量呈γ密度函数分布．随着节位的增高,各节位上的小花数量呈Ｌｏｇｉｓｔｉｃ曲线形式减少．小穗数和小花数均随节位增高呈饱和型指数曲线形式累积增长．     

松嫩平原碱化草甸星星草种群分蘖株延长生殖生长的表型可塑性调节

在松嫩平原碱化草甸,采用大样本随机取样的方法,研究了不同时间到达抽穗初期、抽穗期、开花期和乳熟期的星星草种群生殖分蘖株数量性状的可塑性及其调节规律.结果表明：除在开花期存在一定的波动外,在每5 d的时间里,随着生殖生长时间的延长, 星星草种群在抽穗初期、抽穗期和乳熟期的生殖分蘖株高、分蘖株生物量、花序长和花序生物量均依次显著增加.各生育期的星星草种群生殖分蘖株高与花序生物量呈显著正相关,而与生殖分配呈显著负相关.随着生殖生长时间的延长,抽穗初期、开花期和乳熟期的星星草花序生物量随着分蘖株高增加,其幂函数的增长速率均呈增大趋势.生殖生长时间延长10 d,其抽穗初期和抽穗期的生殖分配直线下降速率分别降低了43.2%和44.31%;延长5 d,乳熟期的下降速率降低了130%.表明星星草种群分蘖株生殖生长的表型可塑性调节遵循着一定的规律.     

Differential responses to defoliation frequency in little bluestem (<Emphasis Type="Italic">Schizachyrium scoparium</Emphasis>) in tallgrass prairie: implications for herbivory tolerance and avoidance

Plant responses to herbivory are complex. In grasses, relative growth rate (RGR), seed, and vegetative reproduction, resource allocation, and architecture vary differentially and often nonlinearly with grazing intensity. High grazing tolerance may be achieved through compensatory photosynthesis and leaf growth, or through demographic mechanisms such as activation of a belowground dormant bud bank. This study assessed the relationship between grazing frequency and responses of Schizachyrium scoparium (little bluestem) in a tallgrass prairie, and examined the roles of tiller growth, reproduction, and bud (meristem) populations in its persistence under grazing. Genets were subjected to varying simulated grazing frequencies for a period of 2 years. Strong differential responses were observed among plant traits. RGR, biomass, and flowering showed strong nonlinear reductions in response to increasing clipping frequency, with no evidence of threshold effects. However, meristem density was unaffected, and plants maintained a large bud bank across all clipping treatments. Tiller natality decreased initially, but increased with >4 clippings, suggesting that declines in tiller RGR are partially offset by increasing tiller natality, and that variation in genet size is driven more by demography than by variation in individual tiller growth. Increased grazing frequency also resulted in differential activation of buds at different positions (emerging within vs. outside the subtending leaf sheath), explaining the shift to a more prostrate growth form observed in many caespitose grasses under persistent grazing. Thus, although this grass species lacks the capacity for compensatory foliage re-growth, the maintenance of a large dormant bud bank and the differential activation of buds in different positions contribute to its grazing tolerance and avoidance, respectively, and its long-term persistence in grazed grasslands.     

2种土壤上羊草生长动态和主要矿物质含量的比较分析

以4叶龄羊草实生苗为实验材料,将其移栽到不同pH的黑土和盐碱土上,观察土壤盐碱胁迫对移栽羊草幼苗生长动态和主要矿物质含量的影响.结果表明,在盐碱土上,羊草幼苗生长速率较在黑土上显著降低,分蘖能力显著下降,其株高、叶片数和分蘖数分别降至黑土上的93.1%、94.4%和78.1%;羊草在盐碱土上地上部和地下部干重分别是黑土上的91.8%和92.1%,但地下部根茎较为发达,其数量和长度分别比黑土上显著增加48.9%和22.5%;盐碱土上羊草植株钠离子含量显著高于黑土,全磷和钾离子含量显著低于黑土,全氮含量与黑土上没有显著差异.研究发现,羊草在盐碱土上具有发达的根茎且能维持较高含水量,从而表现出较强的耐盐碱能力.     

Plasticity of rice tiller production is related to genotypic variation in the biomass response to elevated atmospheric CO2 concentration and low temperatures during vegetative growth

Appropriate resource partitioning to either production of new tillers or growth of individual tillers is a critical factor for increasing rice biomass production and facilitating adaptation to climate change. We examined the contributions of genotypic variation to the tiller number and individual tiller growth of 24 rice cultivars in response to an elevated atmospheric CO₂ concentration [CO₂] (control + 191 μmol mol⁻¹) and a low air temperature (control minus 4.7 °C) during 56 days of vegetative growth after transplanting. For all genotypes combined, biomass increased by 27% under elevated [CO₂] and decreased by 34% at low temperature, with a significant genotype × temperature interaction. The increase caused by elevated [CO₂] resulted from increased tiller number, and the decrease caused by low temperature resulted from decreased growth of individual tillers. Despite the different overall responses to elevated [CO₂] and low temperature, most of the genotypic variation in biomass at elevated [CO₂] and low temperature was explained by the responses of tiller number rather than by individual tiller growth. The genotypes with the highest biomass response to elevated [CO₂] had a smaller reduction of biomass under low temperature. These results highlight the greater importance of genotypic variation in tiller number than in individual tiller growth in the response of biomass to environmental change.     

水稻主茎节位分蘖及生产力补偿能力

本研究选用两个籼稻杂交品种西农优1号和冈优725,采用人工去蘖形成分蘖初期的早发、中发、迟发三个处理,在群体条件下研究分蘖和生产力的补偿能力。本研究发现,迟发处理高节位群的分蘖补偿能力最明显,但绝对补偿量小。迟发处理高节位群的生长势、有效分蘖倍数增加,抽穗期单茎叶面积有增加的趋势,但抽穗期有效穗数、叶面积系数降低;迟发处理冠层光分布增加,叶绿素、蛋白质含量提高,叶片细胞内保护酶类(Superoxide dismutase, SOD、catalase,CAT)活性下降慢,叶片衰老慢,但是漏光率增加,截光率下降;迟发处理净光合生产率（Net assimulation rate, NAR）增加,同化物分配合理,经济系数有增加的趋势,但物质积累速度（Crop growth rate ,CGR）和干物质生产量减少。在本实验条件下,早发与中发处理的经济产量差异不显著,但早发与迟发处理的经济产量差异达极显著。本研究结果表明大苗秧对生物、非生物因素胁迫,如本田前期一定程度的人工去蘖,具有一定的分蘖补偿能力。     

Characteristic Responsiveness of Modular Populations of Kobresia humilis to Grazing in Alpine Meadow

The seasonal dynamics and grazing responsiveness of modular populations of Kobresia humilis were studied at the fourth year (1991) of grazing under different stock intensities and after resting for 1 year (1993) in alpine meadow. The results showed that the number of tillers and leaves per ramet of modular populations of Kobresia humilis increased and the time for which the number of cumulative surviving leaves reaching its maximum was delayed with the increase of stock intensity. The seasonal dynamics of tiller, flowering tiller and total cumulative leave of the populations displayed similar variations with the change of grazing intensities. Two peaks of growth rate of tiller population were observed at the middle and last ten days of May and at the last ten days of August respectively. The peak of death rate of tiller population was at the end of season of growth. The cycle of initiation and death of leaf was nearly synchronous with that of tiller. The greatest risk of leaf death was also in concert with the highest rate birth. The pattern of survival curves was of the “Deevey type Ⅰ” for tiller populations and of the “stepwise” type for leaf populations respectively. And different stock intensities had no effect on the patterns of survival curves, however, their im-pacts on the differences in the number of tiller and leaf populations of Kobresia humilis remained 1 year after stop grazing.     

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。