Alteration of reproductive effort by a monogenic,recessive mutation in jute (Corchorus capsularis L.)

Summary Reproductive effort (RE) of a day-length neutral mutant TCJ-5, its parent, and two other cultivars of jute (Corchorus capsularis) was estimated as reproductive biomass/aerial biomass. Plant height at flowering and aerial biomass were significantly higher in the mutant, while the reproductive biomass at 55 days after flowering was statistically equal. Therefore, the estimated RE was significantly lower in the mutant compared to the parent and other cultivars. The lower RE of the mutant was due to delayed initiation of flowering and additional vegetative growth in this period. The results show alteration of RE by a recessive mutation.     

唐古特雪莲花部特征及生殖分配的海拔差异

为探究高山植物生殖分配策略以及分析唐古特雪莲花部特征对海拔梯度的响应机制,该研究利用采样调查法和烘干称重法,对分布在青藏高原东缘不同海拔14个居群的唐古特雪莲花部特征和生殖分配进行了研究。结果表明:(1)繁殖分配随个体大小(地上生物量和株高)的增大呈线性递减趋势。(2)花期植株地上生物量、株高、管状小花数目、繁殖器官及营养器官生物量均随海拔升高呈线性递减趋势,管状小花生物量随海拔升高呈线性递增趋势。(3)花期管状小花数量及大小、繁殖器官生物量与营养器官生物量、雄蕊重量和雌蕊重量以及花粉数目与花丝长度之间均存在权衡现象。由此推论:(1)海拔作为外界因子对唐古特雪莲花部特征具有显著的影响,个体大小对其繁殖分配也存在潜在调控作用。(2)在不同海拔梯度上,唐古特雪莲有效地整合了有限的资源,其适应性特征之一就是通过减小个体大小来削弱营养生长以达到促进生殖生长的目的。     

腾格里沙漠人工固沙植被中油蒿的生长及生物量分配动态

植物的资源分配模式反映了对环境的生态适应对策。2007年整个生长季, 采用生物量法对腾格里沙漠东南缘固沙植被区半灌木油蒿(Artemisia ordosica)地上部分各器官的生长及资源分配格局动态进行了研究。结果表明: 不同时期各器官的生长速率不同, 光合产物在各器官中的分配也不是等量的, 而是按一定的顺序在不同时期有不同的分配中心; 2007年油蒿的营养生长、繁殖输出、生殖枝大小都显著大于年降水量不足其一半的年份, 而繁殖分配和头状花序大小没有差异; 营养器官生物量大的油蒿总的繁殖输出也大, 但生殖期内营养生长和生殖生长既不同时也不等速, 表明资源分配的权衡(Trade-off)是存在的; 固沙植被建立以后, 随着时间延长, 油蒿的当年总生物量、繁殖输出、繁殖器官生物量分配有减小的趋势, 但不显著。     

Sink-limitation and the size-number trade-off of organs: production of organs using a fixed amount of reserves

To analyze the nature of size-number trade-off of organs, we develop models in which the effects of sink-limitation in the growth of organs and the loss of resources by maintenance respiration are taken into consideration. In these models, the resource absorption rate of an organ is proportional to either its absolute size or its surface area and either the initial size of an organ or the total initial size of the organs produced is fixed. In all models, organs are produced using a fixed amount of reserved resources and no additional resources become newly available for their growth. We theoretically show that size-number trade-offs are nonlinear if the resource absorption rate of an organ is proportional to the absolute size of the organ and the initial size of the individual organs is fixed or if the resource absorption rate of an organ is proportional to the surface area of the organ. In these nonlinear size-number trade-offs, the size of individual organs increases less rapidly than in linear trade-offs with a decrease in the number of organs and the total size of organs is an increasing function of the number of organs produced. This implies that increasing the number of organs produced is advantageous in terms of resource-use efficiency. In contrast, size-number trade-off is linear if the resource absorption rate of an organ is proportional to the absolute size of the organ and there is a linear trade-off between the initial size of organs and their number. To exemplify the effects of those size-number trade-offs on the life-history evolution, we calculate the optimal offspring sizes that maximize the number of offspring successfully being established. In the case of nonlinear size-number trade-offs, the optimal offspring sizes are smaller than the optimal offspring size in the case of linear size-number trade-offs, namely, that in the model of Smith and Fretwell (1974). Our optimal offspring size depends on the metabolism of organ development; the optimal offspring size decreases with an increase in maintenance respiration rate relative to the growth coefficient of organs.     

Effects of denudation and burial on growth and reproduction of <Emphasis Type="Italic">Artemisia ordosica</Emphasis> in Mu Us sandland

Plants in a dune environment have a high risk of being denudated by wind or buried by sand. We conducted a field experiment to assess growth and reproductive performance as well as biomass allocation of Artemisia ordosica after denudation and burial. Height growth decreased after denudation, but remained constant after burial; biomass was reduced by severe burial, but not by moderate ones. Vegetative growth measured by current-year generated vegetative branches declined with increasing severity of burial. Reproductive maturity was not affected by either denudation or burial, and reproduction decreased only after severe denudation. After denudation, biomass allocated to reproduction was greatly reduced, as shown by strongly reduced biomass allocation to fruits and whole reproductive branches, but that allocated to current-year vegetative growth was maintained. Biomass allocation to reproduction and vegetative growth remained rather stable after burial. Current-year reproductive-to-vegetative-biomass ratio was lower after denudation than after burial, indicating that vegetative growth was more favored by A. ordosica after denudation. These modifications are adaptive in the fluctuating environment of mobile sand dunes where denudation and burial frequently occur.     

Patterns of resource allocation in the dioecious alpine herb Aciphylla simplicifolia (Apiaceae)

Abstract Patterns of reproductive and vegetative biomass allocation were compared in male and female plants of the alpine herb Aciphylla simplicifolia. Male and female plants had similar vegetative biomass but differed in the pattern of resource allocation. Inflorescences of males and females were similar in weight at the time of flowering, but differed in biomass allocation to some structures within the inflorescences, particularly those associated with ovule production and pollinator attraction (number and size of flowers). At the time of fruit production, female inflorescences were 2.6 times heavier than at flowering with developing fruit six times heavier than flowers. In addition to the increase in biomass allocated to structures associated with the provisioning and dissemination of seed, support structures (main and side stalks) were also heavier. As a result of this additional investment of resources at the time of fruit production, the reproductive effort (RE) of female plants was much higher than that of males: 37% of above ground biomass compared with 21% for males. Differences in RE did not change with plant size; however, allocation to reproduction appeared to be a constant proportion of biomass over nearly all plant sizes sampled. These results show that sex‐specific resource allocation can be a complex of temporal and morphological patterns.     

两种生境中薇甘菊种群的生物量生殖分配

于2004年薇甘菊（Mikania micrantha）生殖阶段的现蕾期至种子成熟期,从种群和构件水平上研究了两种生境（林窗和开阔地）中薇甘菊种群的生物量生殖分配。结果表明,在生殖生长过程中,两种生境中的种群用于营养生长的生物量分配均占有绝对优势,而生殖生长的波动相对较大。花序的生物量分配（RA）总体上均呈现由低到高的变化趋势。在不同时期,林窗薇甘菊种群的营养枝生物量分配均小于开阔地,而除了种子形成期和种子成熟期以外的其它各个时期,林窗中生殖枝的生物量分配均大于开阔地,林窗中花序的生物量分配均显著大于开阔地。表明薇甘菊能有效权衡其在不同生境中的繁殖策略,开阔地中的薇甘菊种群的繁殖策略倾向于克隆繁殖,而林窗生境中薇甘菊种群则相对更倾向于有性生殖。     

狮牙草状风毛菊果期资源分配对海拔的响应

植物资源分配是目前植物生态学研究的热点问题, 主要集中在性分配和繁殖分配两个方面。该研究以分布在青藏高原的狮牙草状风毛菊(Saussurea leontodontoides)作为研究材料, 研究了6个海拔高度上果期植株的繁殖特征及资源分配的差异, 并用异速模型分析了繁殖性状及资源分配与个体大小的关系。结果显示: 1)狮牙草状风毛菊的个体大小、繁殖器官生物量、营养器官生物量、种子数和营养分配均与海拔存在极显著负相关关系, 百粒质量和繁殖分配与海拔存在极显著正相关关系。2)在不同海拔高度下, 百粒质量、种子数、繁殖器官生物量及营养分配与植株个体大小呈正相关关系; 繁殖分配与植株个体大小呈负相关关系; 而营养器官生物量与植株个体大小呈极显著正相关关系。这表明海拔和个体大小对狮牙草状风毛菊的繁殖对策有不同程度的影响, 狮牙草状风毛菊通过增加繁殖部分的生物量和百粒质量来适应高海拔的胁迫环境。     

Reproductive allocation in hermaphrodite and female plants of Sidalcea oregana SSP. spicata (Malvaceae) using four currencies

Reproductive allocation was investigated in female and hermaphrodite plants of gynodioecious Sidalcea oregana ssp. spicata. Total reproductive investment and partitioning of that investment was documented at the level of whole plants in terms of four ecologically relevant currencies: biomass, nitrogen, phosphorus, and potassium. Nutrient augmentations in the field confirmed that nutrients were limiting plant vegetative growth and propensity to flower; thus the use of these nutrients as currency was appropriate. Once the effects of plant size were removed, the sex morphs allocated similar total amounts of biomass, nitrogen, phosphorus, and potassium to reproduction, but partitioned those differentially. For any given individual size, females allocated larger proportions of their reproductive resource budgets to seeds. Hermaphrodites' reproductive investment in pollen and flowers was allocated at the expense of allocation to seeds. These data are relevant to the evolution of gynodioecy from hermaphroditism and support the hypothesis that females reallocate resources not spent on pollen to seeds.     

Timing of seed germination and the reproductive effort in Xanthium canadense

The effect of different dates of germination on the timing of flowering and the final reproductive yield was examined in a short-day annual plant Xanthium canadense (cocklebur). Delays in germination of 30 and 60 days deferred flower initiation by 2 and 9 days, respectively. Although plants that germinated later were smaller because of the shorter growing period, the reproductive yields did not show as much reduction as the vegetative biomass. The reproductive effort (RE, defined as the ratio of final reproductive yield to the vegetative biomass at the end of the growing season) increased 1.5 and 2.5 times with delays in germination of 30 and 60 days, respectively. A simple model of plant growth was used to analyse the factors involved in the control of RE, which depends only on the dry mass productivity and its partitioning in the reproductive phase, and is independent of the productivity and partitioning in the vegetative phase. Since relative allocation of dry mass to the reproductive part in the reproductive phase was similar for plants with different germination dates, the different REs could be ascribed mainly to differences in productivity of the vegetative parts in the reproductive period. The dependence of RE on plant size is discussed.     

Quantitative analysis of carbon balance for reproduction in woody species

The carbon balance in reproductive organs over the whole reproductive period was estimated for 20 woody species on the basis of the published data on the final dry weight and CO₂ exchange of reproductive organs. The relationship between net respiration and dry weight growth was formulated by a linear function with a negative y-intercept. From this linear relationship, linear relations of dry weight growth and net respiration to net translocation were derived. The size dependence of net respiration showed that the net respiration changed from negative to positive as the final dry weight of the reproductive organ exceeded 0.481 g. The cost for translocation per unit dry weight was much lower in the species with small reproductive organs (<0.481 g) because of their photosynthetic contribution to the weight growth. The relation of dry weight growth/net translocation ratio to net translocation was expressed as a hyperbolic function. The dry weight growth/net translocation ratio remained at 0.650, in the higher range of net translocation, irrespective of woody species. Electronic Publication     

Response of resource allocation of Saussurea leontodontoides during its fruiting stage to the elevation

植物资源分配是目前植物生态学研究的热点问题, 主要集中在性分配和繁殖分配两个方面。该研究以分布在青藏高原的狮牙草状风毛菊(Saussurea leontodontoides)作为研究材料, 研究了6个海拔高度上果期植株的繁殖特征及资源分配的差异, 并用异速模型分析了繁殖性状及资源分配与个体大小的关系。结果显示: 1)狮牙草状风毛菊的个体大小、繁殖器官生物量、营养器官生物量、种子数和营养分配均与海拔存在极显著负相关关系, 百粒质量和繁殖分配与海拔存在极显著正相关关系。2)在不同海拔高度下, 百粒质量、种子数、繁殖器官生物量及营养分配与植株个体大小呈正相关关系; 繁殖分配与植株个体大小呈负相关关系; 而营养器官生物量与植株个体大小呈极显著正相关关系。这表明海拔和个体大小对狮牙草状风毛菊的繁殖对策有不同程度的影响, 狮牙草状风毛菊通过增加繁殖部分的生物量和百粒质量来适应高海拔的胁迫环境。     

Phosphorus addition increased carbon partitioning to autotrophic respiration but not to biomass production in an experiment with Zea mays

Plant carbon (C) partitioning—the relative use of photosynthates for biomass production, respiration, and other plant functions—is a key but poorly understood ecosystem process. In an experiment with Zea mays, with or without arbuscular mycorrhizal fungi (AMF), we investigated the effect of phosphorus (P) fertilization and AMF on plant C partitioning. Based on earlier studies, we expected C partitioning to biomass production (i.e., biomass production efficiency; BPE) to increase with increasing P addition due to reduced C partitioning to AMF. However, although plant growth was clearly stimulated by P addition, BPE did not increase. Instead, C partitioning to autotrophic respiration increased. These results contrasted with our expectations and with a previous experiment in the same set-up where P addition increased BPE while no effect on autotropic respiration was found. The comparison of both experiments suggests a key role for AMF in explaining these contrasts. Whereas in the previous experiment substantial C partitioning to AMF reduced BPE under low P, in the current experiment, C partitioning to AMF was too low to directly influence BPE. Our results illustrate the complex influence of nutrient availability and mycorrhizal symbiosis on plant C partitioning.     

紫茎泽兰的CO2交换特性

紫茎泽兰是一种外来入侵有害植物,从CO2交换特性角度研究其入侵特性的报道较少。对其生殖器官(花和果)和营养器官(茎杆和根系和不同生长条件下的叶片)气体交换特性进行了测定,并与8种本地种和已报到的世界主要草本和木本植物的光合速率、呼吸速率进行了对比。在结果中观察到,不同叶片的净光合能力和呼吸速率差异较大,同一茎杆不同叶片、不同年龄株丛和同一株丛不同年龄分株上叶片、不同生境内嫩叶、成叶和老叶、不同长度节间上生长叶片以及基生叶和顶生叶光合能力都受到气孔限制和非气孔限制(羧化能力)的影响,但不同叶片所受的限制程度不同。综合来看,最大叶片净光合速率为17.6μmol·m-2s-1,分布最集中的区域为11~15μmol·m-2s-1,占所有观测值的50%,而叶片暗呼吸速率70%以上的观测结果在1~3μmol·m-2s-1之间,分布最集中的区域在1.5~2.0μmol·m-2s-1,占所有测定值的40%。生殖器官具有较高的代谢机能,其中幼嫩花蕾的呼吸速率高达37μmol·kg-1DWs-1,其呼吸速率平均比茎杆和根系高出4倍。而且,花蕾、成花和幼果都具有较高的光合能力(毛光合速率分别约为40,16μmol·kg-1DWs-1和11μmol·kg-1DWs-1,是对应呼吸速率的110%,68%和74%),对照同一时期(早春:旱季生殖生长季)的叶片光合能力仅为营养生长季节(夏季)的1/3,生殖器官这种光合作用是对叶片光合能力不足的一种补充。茎杆和根系呼吸速率与直径的关系相似,即直径越小,呼吸速率越高。直径小于0.5mm的根系和茎杆的呼吸速率都在11μmol·kg-1DWs-1以上。与其他植物比较,在温度和根系大小相当的情况下,紫茎泽兰与其它根系呼吸比较并没有明显区别。与已报道的草本植物和木本植物光合呼吸范围来看,紫茎泽兰叶片光合速率介于草本植物系统的中等偏下,位于木本植物系统的中等偏上,而其呼吸速率和草本植物相当但明显高于木本植物。与本地其他伴生植物比较,紫茎泽兰光合能力与本地常绿阔叶树种、落叶阔叶树种相当,而明显高于常绿针叶树种,但与同一时期的草本植物光合能力相当甚至偏低。其呼吸速率与本地草本和木本植物相差不明显。因此,不同生境下和不同生长状态的紫茎泽兰的光合和呼吸速率都具有较强的可塑性,这种可塑性可能有利于其定居不同的生境,即在适宜生境保持最高的光合能力和呼吸代谢水平,利于快速入侵,而在胁迫生境下以避免消亡为主,待机爆发。但是,仅通过比较紫茎泽兰与其它植物的叶片光合速率和呼吸速率不容易判断这一植物的强入侵能力。     

Comparison of production efficiency among field crops related to nitrogen nutrition and application

It has been generally considered that the low productivity of Leguminosae is caused by accumulation in the reproductive organs of a large amount of protein and lipid, since the biochemical costs of synthesizing these compounds is higher than that for carbohydrate. However, we report here on results which show that: the growth efficiencies (dry matter accumulated/ (dry matter accumulated + respiration)) of reproductive organs of Gramineae and Leguminosae were similar; the growth efficiency of rice in the vegetative stage was greater than that of soybean and field bean, regardless of nitrogen application rate; and when ¹⁴CO₂, ¹⁴C-sucrose or ¹⁴C-asparagine were introduced to the leaf at the maturation stage, respiratory loss of the introduced ¹⁴C was greater in soybean and field bean, especially in the light, than in rice. Thus, it is assumed that the low productivity in Leguminosae is caused by a larger respiratory loss under both dark and light condition in the shoot, and not in the reproductive organs.     

Photorespiratory and respiratory decarboxylations in leaves of C3 plants under different CO2 concentrations and irradiances

We used an advanced radiogasometric method to study the effects of short-term changes in CO2 concentration ([CO2]) on the rates and substrates of photorespiratory and respiratory decarboxylations under steady-state photosynthesis and in the dark. Experiments were carried out on Plantago lanceolata, Poa trivialis, Secale cereale, Triticum aestivum, Helianthus annuus and Arabidopsis thaliana plants. Rates of photorespiration and respiration measured at a low [CO2] (40 micromol mol(-1)) were equal to those at normal [CO2] (360 micromol mol(-1)). Under low [CO2], the substrates of decarboxylation reactions were derived mainly from stored photosynthates, while under normal [CO2] primary photosynthates were preferentially consumed. An increase in [CO2] from 320 to 2300 micromol mol(-1) brought about a fourfold decrease in the rate of photorespiration with a concomitant 50% increase in the rate of respiration in the light. Respiration in the dark did not depend on [CO2] up to 30 mmol mol(-1). A positive correlation was found between the rate of respiration in the dark and the rate of photosynthesis during the preceding light period. The respiratory decarboxylation of stored photosynthates was suppressed by light. The extent of light inhibition decreased with increasing [CO2]; no inhibition was detected at 30 mmol mol(-1) CO2.     

Reproductive effort,fecundity and energy allocation in two species of the genus Perinereis (Polychaeta: Nereididae)

Summary

The reproductive effort in terms of fecundity and energy allocation was studied in two species of semelparous polychaetes belonging to the genus Perinereis, living in the same environment, with different reproductive modalities. There is a great individual variability both in terms of reproductive effort and fecundity. Fecundity varied from 4080 to 15000 oocytes in P. rullieri and from 7000 to 26000 in P. cultrifera; no linear relationship was found between oocyte number and total jaw length utilised as size index. The energy content of germinal and somatic tissues was determined by Differential Scanning Calorimeter (DSC). The reproductive effort was calculated as RE = E_G/(E_G + E_S) where E_G is the total energy in germinal tissues and E_S is the total energy in somatic tissues. Reproductive effort is very high with mean values of 0.62 for P. rullieri and 0.79 for P. cultrifera. The different amounts of energy allocated in germinal tissues can be attributed to the different reproductive modalities—P. rullieri reproduces in the atokous phase whereas P. cultrifera has conserved epitoky in its life-cycle. The lack of correlation between reproductive effort and size index strongly suggests that reproductive allocation does not increase with age. In semelparous species the variability in fecundity and reproductive effort observed cannot be interpreted in terms of a trade-off between fecundity and survival as in iteroparous species. In fact, in semelparous an individual allocates all available resources to reproduction and then dies.     

Respiratory energy costs for the maintenance of biomass, for growth and for ion uptake in roots of Carex diandra and Carex acudformis

van der Werf, A., Kooijman, A., Welschen, R. and Lambers, H. 1988. Respiratory energy costs for the maintenance of biomass, for growth and for ion uptake in roots of Carex diandra and Carex acutiformis. - Physiol. Plant. 72: 483–491. The respiratory characteristics of the roots of Carex diandra Schrank and Carex acutiformis Ehrh. were investigated. The aims were, firstly to determine the respiratory energy costs for the maintenance of root biomass, for root growth and for ion uptake, and secondly to explain the higher rate of root respiration and ATP production in C. diandra. The three respiratory energy components were derived from a multiple regression analysis, using the relative growth rate and the net rate of nitrate uptake as independent variables and the rate of ATP production as a dependent variable. Although the rate of root respiration and ATP production was significantly higher in C. diandra than in C. acutiformis, the two species showed no significant difference in their rate of ATP production for the maintenance of biomass, in the respiratory energy coefficient for growth (the amount of ATP production per unit of biomass produced) and the respiratory energy coefficient for ion uptake (amount of ATP production per unit of ions absorbed). It is concluded that the higher rate of root respiration of C. diandra is caused by a higher rate of nitrate uptake. At relatively high rates of growth and nitrate uptake, the contribution of the rate of ATP production for ion uptake to the total rate of ATP production amounted to 38 and 25% for C. diandra and C. acutiformis, respectively. At this growth rate, the respiratory energy production for growth contributed 37 and 50%, respectively, to the total rate of ATP production. The relative contribution of the rate of ATP production for the maintenance of biomass increased from 25 to 70% with increasing plant age for both species. The results suggest that ion uptake is one of the major sinks for respiratory energy in roots. These experimentally derived values for the rate of ATP production for the maintenance of biomass, the respiratory energy coefficient for growth and the respiratory energy coefficient for ion uptake are discussed in relation to other experimentally and theoretically derived values.     

积雪变化对高寒草甸钝苞雪莲(Saussurea nigrescens)繁殖分配及功能属性的影响

季节性雪被对植物的生长繁殖具有深刻影响。为阐明不同积雪梯度下钝苞雪莲各器官生物量、养分含量、繁殖分配及功能属性的变化规律,在青藏高原东缘红原县,通过人工堆积的方法开展积雪梯度（CK、S0、S1、S2、S3）控制实验,测量了不同积雪梯度下钝苞雪莲茎、叶、花苞的养分含量及繁殖分配等特征。结果表明：1）积雪变化没有显著改变钝苞雪莲的繁殖分配,但去除积雪（S0）显著降低了营养器官生物量。2）不同积雪处理下,个体大小与繁殖器官生物量均呈正线性关系（P<0.01）。3）茎部磷（P）含量随积雪量的增加显著升高（P<0.05）;叶部P含量随积雪量的增加先上升后下降,即：S2 > S1 > CK > S3 > S0,且存在显著差异（P<0.05）;各处理下植物的不同器官在养分上主要受氮（N）元素的限制。4）去除积雪（S0）降低了茎干重、株高、茎高、茎分配和单株花苞量,过度积雪（S3）则降低了株高、茎高和花苞长度,中度积雪（S1、S2）则分别降低了花苞长度与单株叶片数。由此可见,不同积雪量并未显著改变钝苞雪莲的繁殖分配,但却改变了其不同器官的功能属性与养分含量,使磷元素成为植物响应积雪变化较为敏感的指标。     

The role of maintenance respiration in plant growth

Abstract Plant growth is the balance of photosynthetic gains and respiratory losses, and it is therefore essential to consider respiration in analyses of plant productivity. The partitioning of dark respiratory losses into two functional components, a growth component and a maintenance component, has proved useful. The growth loss is that associated with synthesis of new biomass while the maintenance loss is that associated with maintenance of existing biomass. Experimental evidence indicates that the respiratory cost of maintenance in herbaceous plants is about equal to the cost of growth over a growing season, with daily maintenace expenditures less important in the small, rapidly growing plant but increasing in significance as plant size increases and the relative growth rate decreases. Because it is such a large fraction of the total carbon budget of a plant, any variations in maintenance requirements may result in significant alterations in productivity. In the present work the theoretical and empirical bases of maintenance respiration are described: magnitudes of maintenance expenditures are summarized; and applications to models of plant growth and productivity are discussed. It is concluded that the costs of maintenance should be included in analyses of plant growth.