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.     

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.     

天津沿海滩涂互花米草种群生殖分株数量特征及生殖分配研究

通过对天津沿海滩涂单优群落的取样调查,研究了互花米草种群生殖分株的数量特征和生殖分配规律。结果表明,在籽实成熟期,互花米草种群单个生殖分株重为15.62±9.26 g,穗和种子重分别为2.68±2.08和1.39±1.12 g,小穗和种子数分别为537.7±362.2和490.2±376.3个,生殖分配Ⅰ和生殖分配Ⅱ分别为15.02±5.83和7.62±3.8%,结实率为81.9 ±28.6%。穗和种子的形成分别需要分株积累3.2和3.6 g以上的生物量。穗长、穗重、种子数、小穗数、生殖分配Ⅰ和生殖分配Ⅱ分别与分株高度呈极显著(p<0.01)的正相关关系。穗重、小穗数、种子重、种子数、生殖分配Ⅰ和生殖分配Ⅱ分别与分株重呈极显著(p<0.01)的线性正相关关系。种子数、小穗数、生殖分配Ⅰ和生殖分配Ⅱ分别与茎和叶鞘生物量分配呈极显著(p<0.01)的负相关关系。穗各构件在空间上的分布也存在较强的规律性。     

荒漠植物白刺属4个物种的生殖分配比较

选定乌兰布和沙漠地区白刺属4种植物为研究对象,通过对其样株在花期的各生殖构件的数量特征及生物量调查,系统研究了唐古特白刺(Nitraria tangutorum Bobr.)、西伯利亚白刺(Nitraria sibirica Pall.)、大白刺(Nitraria roborowskii Kom.)和泡泡刺(Nitraria sphaerocarpa Maxim.)4种白刺属植物在生殖枝水平上的生殖分配。结果表明:不同白刺属植物在分株高度、生殖枝长、生殖枝基径、单枝花数、花序干重、枝叶干重等生殖构件的数量性状方面均有显著差异,其中泡泡刺的各生殖构件的数量均最小;除了西伯利亚白刺的生殖分配值达到44.51%外,其余3种白刺的生殖分配值均没有超过20%。经统计分析,4种白刺种群的生殖枝长分别与分株高度呈显著(P<0.05)的直线性正相关关系;生殖枝花序干重与分株高显著正相关;4种白刺的生殖分配随着分株生殖枝生物量的增加而减少,即白刺的个体大小与生殖分配之间呈现负相关关系。这种生殖分配特点反映了不同白刺植物对生长环境的资源利用、与克隆繁殖的权衡及对生态适应的策略。     

华北平原罗布麻种群生殖分株数量特征及变化规律

通过大样本取样调查,研究了华北平原罗布麻种群生殖分株的数量特征和生殖分配规律．结果表明,在籽粒完熟期,罗布麻种群单个生殖分株重为10．38±7．78g,蒴果生物量和蒴果数分别为1．57±1．59g和7．60±6．56个;种子生物量和种子数分别为0．34±0．33g和582．3±558．7个;生殖分配Ⅰ和生殖分配Ⅱ分别为12．98±7．94和2．75±1．69％．蒴果和种子形成分别需要分株积累1．42和1．77g以上的生物量．蒴果生物量、葫果数、种子生物量、种子数分别与分株总生物量呈极显著的（P〈0．01）线性正相关关系;蒴果数、种子数与茎叶生物量分配呈极显著的（P〈0．01）线性负相关关系;生殖分配Ⅰ、生殖分配Ⅱ和叶生物量分配呈极显著的（P〈0．01）线性负相关关系．单葫果的重量、种子重、种子数、种子毛重、胎座重分别和葫果的长度呈极显著（P〈0．01）的幂函数正相关关系．罗布麻种群生殖分株同时具有同速和异速2种不同增减过程的表型可塑性调节．     

恢复措施对退化草地羊草种群有性生殖数量特征的影响

在封育和翻耙处理的退化羊草草地上,对羊草种群有性生殖的数量特征进行了比较研究．结果表明,翻耙样地羊草种群密度下降显著,生殖蘖密度变化不显著,生殖蘖穗长、节间长、生殖生长比率、穗节数、小穗数、小花数、饱满籽实数和结实率都有显著增长,籽实产量、净籽实重和千粒重分别是封育样地的2．68、3．49和1．3倍．在翻耙样地中,羊草种群发育有复小穗的生殖蘖比封育样地多16％,生殖蘖上复小穗的数量也显著增加,生殖蘖以相对少的小穗,生产了较多的小花和更多的籽实来提高种群的籽实产量．两个样地中羊草种群的生物量生殖分配在种群对生殖蘖RA1、生殖蘖对穗序RA4、穗序对籽实RA6 3个层次上无显著差异,而种群对穗序RA2、生殖蘖对籽实RA5的生殖分配差异显著,种群对籽实RA3的生殖分配差异极显著．     

放牧影响下羊草种群生殖生态学的研究

在种群水平上系统研究了放牧对松嫩草原关草种群无性繁殖、有性生殖和生物量的生殖分配的影响。结果表明,放牧制约了羊草种群无性繁殖和有性生殖的更新途径,表现在随放牧强度增加,无性繁殖体营养技密度、根茎牙密度和有性生殖体种子生物量、结实数和生殖枝分化率等指标均显著下降,是生牧后下降迅速。随放牧强度增加,关草种群根茎生物量的分配比例显著增加,而同化器官、非同化器官和种子生物量分配比例都显著下降,极牧阶段几科     

粤西野生种香根草种群构件特征对密度的响应

对试验田栽种的野生种香根草种群分蘖株各性状对密度的响应进行了统计。结果表明,试验田栽种的香根草在栽种50 d(10月下旬)和240 d(翌年5月)分蘖株数量迅速增加,栽种270 d时密度最大达到了821株·m-2,但并未对香根草数量增多有明显抑制作用。270 d时(6月初),密度处理为80株·m-2的小区未拔节、拔节和总分蘖株数量与其他密度处理小区差异极显著。各小区地上总生物量与单位面积分蘖株数量呈极显著线性相关。未拔节、拔节、生殖株、总分蘖株数量与初始密度呈极显著幂函数形式正相关。虽然栽种270 d时的密度并未对香根草生长产生制约,但分蘖株数量增长的速率已经显著下降。香根草的繁殖特性决定了其在密度很高的情况下仍能良好生长。     

濒危植物七子花的生殖构件特征

对濒危植物七子花(Heptacodium miconioides)的花枝构成及不同类型花序的结实状况进行了研究。结果显示：(1)在黄经洞(种群B),花枝的营养生长旺盛,单枝的花序数和花数多,平均为23．5个和278朵;在狮子岩坑(种群A)．开多轮花的花序比例高．但花枝的花序数较少,单枝的开花数最少。(2)七子花的结实率很低．可育胚珠的平均结实率均在40％左右,且结实率与花序的开花数量呈显著的负相关关系。(3)花序类型对种子重量也有一定的影响,其中种群A的Ⅰ型花序所结果实的种子最大,但这些种子的胚也未发育完全。因此,七子花成为濒危物种的关键并不是结实的数量,而是结实的质量。     

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.     

Is the change of winter wheat yield under warming caused by shortened reproductive period?

Previous reports from laboratory-controlled experiments and models considered that a shorter reproductive period could be the main reason for wheat yield reduction in the warmer world. However, this conclusion needs to be proved carefully by field-scale experiments. In this study, a field-scale continuous open-warming experiment was conducted to quantify the adjustment of winter wheat growth and yield under conventional tillage (CT) and no-till (NT) systems in the North China Plain (NCP). Canopy temperatures were warmed using infrared heaters between 1.0 and 1.6°C (daytime and nighttime, respectively) above the control. Wheat yields under CT were not significantly reduced over the two seasons (2010 and 2011), but yields under NT were 3.3% and 6.1% lower, respectively. The growing seasons for both CT and NT were shortened 6 days in 2010 and 11 days in 2011; however, the reproductive periods were maintained. The shortened days were due to a significantly shorter springtime re-greening stage followed by minimal changes in other phenological stages (jointing, flag completed, heading, anthesis, and grain-filling). The temporal advance by warming resulted in lower growing-season mean air temperatures (MAT) for warmed plots than the control from 0.23 to 4.22°C for the same subsequent phenological stages. Warming increased the number of tillers m⁻² and kernel weight, but tended to decrease the number of spikes m⁻² in the two tillage systems. The heavier kernels offset the yield reduction from smaller number of spikes. Warming increased the wheat aboveground biomass from 10% to 20% suggesting the potential to sequester more CO₂. This study suggests that winter wheat might adjust its growth (shortened vegetative period to maintain reproductive period) to partly compensate for the negative effects from global warming in this temperate irrigated cropland.     

Growth and production characters of elymus cylindricus in different shortening heading time

Ramet modules in a certain population differ in terms of functions, which accounts for different contributions of the same ramets. Shortening heading time brings about different contributions of such modules. Ramets heading one after another were treated as a continuum in respective cohorts of Elymus cylindricus aged two. The reproductive ramets that head earlier were marked with tags every four days during the whole heading stage from the beginning to the end, after which all the labeled ramets at the maturity period were gathered. The results showed that, the height and biomass of ramets, the length and biomass of inflorescences, percentage of inflorescence length to ramet height, percentage of inflorescence biomass to ramet biomass, the number and biomass of seeds, seed-setting rate, and percentage of seed biomass to ramet biomass declined with the increasing intensity of heading time shortening as displayed with linear or quadratic function. Ramet characteristics weakened remarkably when shortened heading time added up to 17 days. The biomass distribution in relation to inflorescence and seed maintain a stable rate at the early heading stage and dwindled quickly at the near-end stage, but the biomass of ramets remain constant throughout the entire heading stage. The ramets with earlier heading time make greater contribution to the survival of population than the shortened heading time in this species of bunchgrass.     

长白山区华北翦股颖无性系构件的结构及生长

采用大样本随机挖取单个无性系的调查和测定方法,分析了长白山区华北翦股颖无性系构件的结构及生长规律.结果表明,在籽实乳熟期,华北翦股颖无性系构件是由营养枝和生殖枝组成,其中,以生殖枝数量和生物量所占比例最大,分别为93.3%和97.1%.华北翦股颖无性系构件的关系中,生殖枝数量和生物量以及分株总数量和总生物量均随着丛径的增加呈幂函数异速生长(R2=0.661～0.712).生殖枝数量与分株总数量之间以及生殖枝生物量与分株总生物量之间均呈极显著线性正相关(R2为0.997和0.965).     

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     

Regulatory Mechanisms of Reproductive Effort in Plants 1. Plasticity in Reproductive Energy Allocation and Propagule Output of Helianthus annuus L. (Compositae) Cultivated at Varying Densities and Nitrogen Levels

Abstract Plasticity in growth, reproductive energy allocation (RA), and reproductive output were investigated in Helianthus annuus L. cultivar. Russia (Compositae) grown under varying densities and soil nitrogen levels. The role and behaviour of pollinators in seed production was also examined.
Exceedingly marked plastic responses were detected in individual biomass, the patterns of resource allocation to total reproductive structures (RA) and also to propagules, fecundity, reproductive outputs, and propagule size and weight under changing densities and soil nitrogen levels. Plants cultivated at higher densities exhibited proportionately lower individual biomass, lower RA, lower fecundity, lower seed output, and smaller seed size in response to increasing density and decreasing soil nitrogen levels. However, differences due to different N-levels were not as great as those to changing density.
One of the most significant findings was that seed production under limited resource availability, i.e., lack of ample solar radiation and soil nutrients, due to strong interference at higher density plots, is exceedingly costlty , This was most clearly demonstrated by a very sharp increase in relative energy partitioning to a single propagule in response to the increased density and decreasing nitrogen levels, the relative energy cost to a single achcne (R_A) increasing from one to twenty-fourfold. Reproduction was also affected by pollinator-limitations, and seed size showed a marked position effect.     

Optimal Reproductive Strategy of Plants, with Special Reference to the Modes of Reproductive Resource Allocation

Abstract A growth model for reproductive energy allocation pattern and schedule is proposed. Assumptions are as follows: (1) the assimilation rate for an individual is given by a logistic curve of vegetative dry weight; (2) size variability is expressed by the parameter W of the logistic curve (asymptotic value of vegetative dry weight); (3) a plant controls allocation of the assimilate to vegetative and reproductive structures so as to maximize the reproductive energy investment at the end of the growth period. The models were analyzed in comparison with field and experimental observations and gave reasonable explanations for the reproductive allocation pattern of individuals which reflects ecological preferences and life history characteristics, such as environmental conditions of habitats (stable or changing), length of life span (annual, biennial or perennial) and growth form (erectophile or planophile). Decreasing RA (reproductive allocation) with individual size and delayed switchover time from vegetative to reproductive growth were found in plants which occur in stable environments and have a more or less fixed growth period; in those which occur in changing environments where growth period depends on individual size, RAs that remain constant or increase with variations in individual size and early switchover time were detected. Most perennials conform to the former case, but annuals and biennials conform to the latter case. Under extremely overcrowded conditions, planophiles, which are much more subject to crowding effect than erectophiles, tend to have increasing RA with increasing size, while erectophiles tend to have almost constant RA irrespective of size. These trends are discussed in the light of the life history characteristics and ecological distribution of plant species studied.     

Phenotypic plasticity of life history characteristics: quantitative analysis of delayed reproduction of green foxtail (Setaria viridis) in the Songnen Plain of China

Green foxtail (Setaria viridis L,) is a common weed species in temperate regions. Research on the effect of delayed reproduction on the phenotypic plasticity and regularity of the vegetative and reproductive growth is of vital significance for understanding population regulation and control of the weed in the growing season, Green foxtail seeds were sown every 10 days from 25 June to 24 August of 2004. The growth and production metrics were measured via harvesting tufts and statistical analysis was carried out. The results showed that the reproductive tillers, seed number, seed biomass and one thousand-seed weight of plants at the first sowing (25 June) approximately increased 28.8, 7827.0, 1104.0 and 12.3 times compared with that at the last sowing (24 August), respectively. Total tillers, reproductive tillers and height increased linearly as the reproductive period delayed, however, biomass increased exponentially. Quadratic equations best explained the relationships between the delayed reproductive period and seed number, Inflorescence length, one thousand-seed weight, seed biomass. Based on the quantity and quality of seed production, weeding young seedlings emerging before July can be the most effective weed-control strategy in the Songnen Plain.