植物光合产物分配及其影响因子研究进展

植物光合产物分配受环境因子和生物因子的共同影响。为增进对植物对全球变化响应的理解, 从植物个体水平与群落/生态系统水平综述了植物光合产物分配的影响因子与影响机理的最新研究进展。植物个体在光照增强及受水分和养分胁迫时, 会将光合产物更多地分配到根系; CO₂浓度升高对植物光合产物分配的影响受土壤氮素的制约, 植物受氮素胁迫时, CO₂浓度升高会促进光合产物更多地分配到根系; 反之, 对植物光合产物分配没有影响。植物群落/生态系统的光合产物分配对环境因子的响应不敏感; 光合产物向根系的分配比例随其生长阶段逐渐降低。功能平衡假说、源汇关系假说和相关生长关系假说分别从环境因子、个体发育和环境因子与个体发育协同作用方面阐述了植物光合产物分配的影响机理。在此基础上,指出了未来拟重点加强的研究方向: 1)生态系统尺度的光合产物向呼吸部分的分配研究; 2)地下净初级生产力(belowground net primary productivity, BNPP)研究; 3)温室和野外条件下及幼苗和成熟林光合产物分配对环境因子响应的比较研究; 4)生态系统尺度的多因子控制试验; 5)整合环境因子和个体发育对植物光合产物分配格局的影响研究。     

冬小麦干物质在各器官中的累积和分配规律研究

为修正冬小麦生长模型中的干物质分配,通过田间试验,对冬小麦干物质累积和在不同器官中的分配进行了描述。并且在此基础上结合文献资料,对冬小麦光合产物在各器官中的分配和转移系数的计算方法进行了探讨,分析了两者随相对发育阶段（RDS）的变化规律,并建立了函数表。同时运用试验资料进行了实地验证,取得较好的效果。     

应用细胞自动机对一年生植物种群扩散进行理论研究

应用细胞自动机方法构造了用于研究一年生植物扩散的理论模型并应用该模型模拟了一年生植物（杂草）种群在同质环境中的扩散。一年生杂草种子的扩散距离和分布是其种群扩散的主要方式,故本文将其种子扩散分布作为构建邻域细胞函数的基础。根据Howard(1991)^[1]提供的某一年生杂草种子的扩散数据,本文导出了一个25邻的邻域细胞函数和相关的转移函数。建立了一个受控的细胞自动机模型。通过模拟,发现在同质环境中聚集在一起的一年生植物杂草越多就需要越大的控制力才能限制它们扩散;生长于农田边缘的杂草更容易被控制。这些模拟结果表明该模型能较好地表现生态学中的两个众所周知的现象;生物的聚集效应和边缘效应。希望自动机方法和在本文获得的知识将有助于我们制订植物种群的最优管理策略。     

脱落酸在光合产物分配中的作用

作物产量最终依赖于光合产物和矿质离子在相互竞争的库器官之间的分配方式,因此,弄清光合产物分配的控制机制显然具有十分重要的意义。植物激素在光合产物分配中起着重要的作用。业已证明,生长素、赤霉素和细胞分裂素能够通过刺激生长过程或直接影响韧皮部装入和卸出或由源向库的运输而增加源和库的强度.近年来,通过对库中脱落酸浓度和生长速率之间的相关性,脱落酸对韧皮部装入和卸出以及库对糖的吸收的响影等方面的研究,证明脱落酸也参与光合产物分配的调控。本     

不同密度猪毛菜形态结构性状及生物量分配策略的异速关系

植物的生长特性随环境条件的变化具有可塑性，而不同的环境因素对植物可塑性的影响也不尽相同。利用异速分析的方法，通过模拟退化草地恢复过程中猪毛菜（Salsola collina）的不同种群密度（16、44、100、400株/m²），研究其形态结构性状及生物量分配策略的异速关系在种群密度间的差异。结果表明，种群密度增大能抑制猪毛菜的生长，而且对猪毛菜的株高、根长、一级分枝数、二级分枝数、三级分枝数以及总分枝长均产生了极显著的影响，表明种群密度的变化使得植物的高生长和侧向生长发生了显著变化。种群密度的变化也引起了植物生物量的变化，其中植物根、茎、叶间的生物关系是一种表观可塑性，植物的生长策略未发生改变，只是植物个体大小发生改变引起的生物量分配的变化。植物株高、总分枝长、一级分枝数及繁殖分配的变化，是由种群密度变化引起的，植物的适应策略发生了改变，是真正的可塑性。种群密度改变了植物的繁殖分配策略，而未改变植物叶的分配策略，说明当环境发生变化时，植物调整了其繁殖策略以适应环境因素的改变，以保证种群的生存繁衍。     

基于光合产物动态分配的玉米生物量模拟

光合产物分配是作物生长发育及生物量形成的关键环节,也是作物生长模拟的重要内容.本研究依据光合产物分配机理,结合玉米不同生长阶段的光合产物分配特点,构建了玉米光合产物分配模型.与WOFOST模型的CO₂同化模块相结合,实现了对玉米各器官生物量动态的逐日模拟.利用锦州农田生态系统野外观测站5年的春玉米大田试验资料对模拟效果进行了验证.结果表明: 模型能解释总生物量变化的95.4%;对营养器官生物量变化的解释率达87.0%;对叶、根、茎生物量变化的解释率分别达85.3%,67.9%和76.5%;对穗生物量变化的解释率达87.5%.模型可实现玉米各器官的生物量动态的准确模拟.     

古尔班通古特沙漠南缘3种生活型草本植物生物量分配及相关生长关系

为了解古尔班通古特沙漠不同生活型草本植物的生物量分配特征,通过取样调查当地34种草本植物的生物量研究表明：（1）采集到的每个物种样本的总生物量大多小于4 g,其中多数个体（大于80%）的地上与地下生物量分别在2和0.5 g以内,根冠比主要集中在0.25以内;（2）类短命植物向地下部分分配较多生物量,根冠比较大,集中分布在1.67左右;短命和一年生长营养期草本向地下部分配的生物量远小于类短命植物,两者的根冠比较小,主要集中在0.15左右;（3）短命植物地下与地上部生物量间为等速生长关系,而类短命植物和一年生长营养期草本植物地下与地上生物量间为异速生长关系,其中类短命植物随个体增大向地下部分配生物量的比例增多,而一年生长营养期草本则相反。综上所述,短命、类短命和一年生长营养期草本植物地下与地上生物量间具有不同的分配特征,与各自独特的生活史特征相一致。     

油菜素内酯对大豆生长及结实性的影响

油菜素内酯(Brassinolide,BR)是一新型植物激素,在许多方面参与植物生长发育过程的调节,如促进作物营养体的生长、调节作物光合产物的分配和提高结实率等。在早期采用油菜粗提物的菜豆试验中,曾得到豆荚增产43.6％的明显效果。尔后,在     

Biomass allocation and leaf stoichiometric characteristics in four desert herbaceous plants during different growth periods in the Gurbantünggüt Desert,China

荒漠草本植物是荒漠生态系统物种多样性的主体, 对其生物量分配及叶片化学计量特征随植物生长的变化规律的研究有助于深入了解荒漠草本植物生存策略和功能特征。该文选择古尔班通古特沙漠4种优势草本(2种短命植物, 2种一年生长营养期植物)为研究对象, 通过野外原位多时段取样, 对比研究了四者生物量分配、叶片N-P化学计量学随植物生长的变化特征, 以及二者之间的关系。结果表明, 在生物量累积过程中, 4种植物根冠比逐渐减小, 地上与地下生物量间的相关生长关系也发生变化, 其中琉苞菊(Hyalea pulchella)和角果藜(Ceratocarpus arenarius)的相关生长指数先增加后减小, 并趋于稳定, 而尖喙牻牛儿苗(Erodium oxyrrhynchum)和沙蓬(Agriophyllum squarrosum)的相关生长指数由小到大并趋于等速生长。琉苞菊叶片N、P含量呈逐渐增长趋势, 而另外3种植物呈下降趋势, 表明所研究的荒漠植物在生长过程中, 叶片N-P化学计量发生改变, 叶片化学计量特征与生物量指标的相关性较弱。     

高产杂交稻‘两优培九’剑叶及其叶鞘的光合作用

以高产杂交稻‘两优培九’（LYP9）和杂交稻‘汕优63’（SY63）为研究材料,用HC同位素示踪等技术,研究了剑叶的叶片与叶鞘的光合作用与光合产物向叶鞘的分配。结果表明,‘两优培九’剑叶及其叶鞘的净光合速率的均值均高于‘汕优63’;剑叶叶鞘中部群体内透光率均值、倒二叶叶鞘中部群体内的透光率均值高于‘汕优63’;剑叶及其叶鞘的Rubisco初始羧化活性均值、总羧化活性均值和活化率均值都高于‘汕优63’,其差异大多数时期达显著水平。‘两优培九’叶鞘光合产物的输出比‘汕优63’快,其叶鞘光合产物输送到穗部的量即转化为经济产量的量比‘汕优63’高。‘两优培九’叶鞘的光合产物主要输送到穗等部位,对产量有一定的（约为15％）贡献。     

Nitrogen from senescing lower leaves of common bean is re-translocated to nodules and might be involved in a N-feedback regulation of nitrogen fixation

The objective of the present study was to elucidate whether remobilized N from lower leaves is involved in causing the drop in N(2) fixation during pod-filling in common bean (Phaseolus vulgaris L). Moreover, we addressed the question of whether remobilized N from lower leaves would reach the nodules. Nodulated common bean plants were grown in a growth chamber in quartz sand. During a 2-week period, at vegetative and at reproductive growth, 50% of the leaves (lower part) were either excised or individually darkened, thereby removing the same photosynthetic capacity yet allowing N to be remobilized from the darkened leaves. Moreover, at the vegetative growth period, three lower leaves per plants were (15)N labelled by applying (15)NH(4)NO(3) prior to imposing the darkening treatment. Leaf darkening at vegetative growth induced N remobilization as well as reduced N(2)-fixation rates and growth. Leaf excision at reproductive growth enhanced N(2) fixation. Changes in N(2)-fixation rates were in all cases the result of altered growth rates, while the % N in the whole plant and in various plant parts remained conserved. Directly after leaf labelling, but also at the end of the vegetative growth period, substantial amounts of (15)N from the leaves could be recovered in nodules in the control, and in higher amounts in the leaf-darkening treatment. It is proposed that nitrogen from leaves circulates within the plant via nodules, and that the strength or composition of this circular flow may be the signal for a putative N-feedback effect.     

How do sink and source activities influence the reproduction and vegetative growth of spring ephemeral herbs under different light conditions?

Spring ephemeral herbs inhabiting deciduous forests commonly complete reproduction and vegetative growth before canopy closure in early summer. Effects of shading by early canopy closure on reproductive output and vegetative growth, however, may vary depending on the seasonal allocation patterns of photosynthetic products between current reproduction and storage for future growth in each species. To clarify the effects of sink–source balance on seed production and bulb growth in a spring ephemeral herb, Gagea lutea, we performed a bract removal treatment (source reduction) and a floral-bud removal treatment (sink reduction) under canopy and open conditions. Leaf carbon fixations did not differ between the forest and open sites and among treatments. Bract carbon fixations were also similar between sites but tended to decrease when floral buds were removed. Seed production was higher under open condition but decreased by the bract-removal treatment under both light conditions. In contrast, bulb growth was independent of light conditions and the bract-removal treatment but increased greatly by the bud-removal treatment. Therefore, leaves and bracts acted as specialized source organs for vegetative and reproductive functions, respectively, but photosynthetic products by bracts were flexibly used for bulb growth when plants failed to set fruits. Extension of bright period was advantageous for seed production (i.e., source limited) but not for vegetative growth (i.e., sink limited) in this species.     

Distribution and utilization of assimilated carbon in red clover during the first year of vegetation

Summary The pattern of distribution of¹⁴C labelled assimilates and translocation with time was measured in red clover during one reproductive cycle. Measurements were made on whole plants grown outdoors in pots by exposing the aerial parts to¹⁴CO₂ during one photoperiod. Simultaneously, root respiration and N₂ fixation were recorded.At the beginning of the vegetative period, 2/3 of the assimilates remained in the leaves (basal leaves), and 1/3 were directed to the root system. Then the development of branches required as much as 40% of the C and the root allocation decreased. Reproductive structures diverted 17% of the current photosynthates. Nitrogen fixation was optimal during the maximum extension of the basal leaves and decreased during the development of branches. During this period, C allocation to the nodulated roots was high with an estimated amount of 3.2 mg of C per mg of N fixed.With time, translocation occured within the foliage, from basal leaves to the leaves of the branches and to the new basal leaves developed after senescence of the branches. Remobilization to the reproductive structures remained minimal indicating that flower and seed growth was supported by current photosynthesis.     

Short-term UV-B radiation and ozone exposure effects on aromatic secondary metabolite accumulation and shoot growth of flavonoid-deficient Arabidopsis mutants

The presence of UV-absorptive substances in the epidermal cells of leaves is thought to protect mesophyll tissues from the harmful effects of UV-B radiation. We examined the influence of short-term UV-B exposures on UV-absorptive (330 nm) sinapates and flavonols, and on shoot growth of the Arabidopsis wild type ecotype Landsberg erecta and two mutants. 114 deficient in chalcone synthase, and 115 , deficient in chalcone/flavonone isomerase. Sequential ozone exposures were used to determine the effects of oxidative stress The levels of sinapates and flavonols on a leaf fresh weight basis increased substantially in the wild type and sinapates increased in the 114 mutant in vegetative vegetative/reproductive transitional and reproductive stage plants in response to short-term (48h) UV-B radiation. When UV-B was discontinued the levels generally decreased lo pre-exposure levels after 48 h in vegetative/reproductive but not in reproductive plants. Exposure to ozone before or alter UV-B treatment did not consistently affect the levels of these UV-absorptive compounds. Dry matter accumulation was less affected by UV-B at the vegetative and reproductive stages than at the vegetative/reproductive stage. At the vegetative/reproductive stage, shoot growth of all 3 genotypes was retarded by UV-B. Growth was not retarded by short-term ozone exposure alone but when exposure to ozone followed UV-B exposure, growth was reduced in all genotypes. Leaf cupping appeared on 115 plants exposed to UV-B.     

Ecology And Growth Habit Of Laveineopteris: A Gymnosperm from the Late Carboniferous Tropical Rain Forests

Cyclopterid leaves were borne on the same Late Carboniferous medullosalean plants that bore the pinnate fronds currently known as Laveineopteris . They were morphologically and anatomically different from the pinnate foliage, and presumably were also physiologically different. The cyclopterids are here interpreted as having been shade leaves and the pinnate foliage sun leaves. The juvenile Laveineopteris plant probably consisted of a monopole sapling bearing only cyclopterid leaves, which optimized growth in canopy shade conditions. On reaching the canopy level, the plant produced a crown of pinnate sun leaves. Cyclopterids were also borne epiphyllously in the proximal parts of the pinnate fronds; this may have represented a transitional light–level between canopy and subcanopy conditions. Thus, in this reconstruction, the cyclopterid leaves were complementary to the pinnate foliage of the adult Laveineopteris plant, and played a key role in its growth habit and ecology.     

Distribution of 14C-sucrose applied to leaves at different nodes of okra (Abelmoschus esculentum) during flowering and early pod growth

The distribution pattern of ¹⁴C-sucrose from ¹⁴C-sucrose applied to vegetative okra plants and leaves 1–9 on separate plants during the green pod development stage were investigated in relation to duration and leaf position. Results indicated bi-directional transport of assimilates to both apical and basal portions of the stem. Within 48 h ¹⁴C moved to all plant parts; stem and leaves appeared to be strong sinks. In plants fed at the vegetative stage, 48 h after feeding, 66% of the fed activity was exported from the fed leaf. At the pod development stage, about 35% of the activity exported from the fed leaf was present in green pods and 65% in vegetative parts. In plants where leaf 1–9 was fed, irrespective of the position of the fed leaf, the subtending fruit was the strongest sink among the reproductive parts. Leaves and stems were the principal sinks.     

Multiple switches between vegetative and reproductive growth in annual plants

A model of growth and reproduction in annual plants was developed by Cohen (1971, J. Theor. Biol.33, 299–307) to determine the allocation strategy which maximizes seed yield. The model divides the plant into vegetative and reproductive parts and predicts that yield is maximized by a strategy consisting of a switch from purely vegetative to strictly reproductive growth. We generalize Cohen's model to include vegetative and reproductive loss terms. Both growth and loss rates are allowed to vary with time. Using optimal control theory we find that seed yield is maximized by a strategy consisting of multiple switches between vegetative and reproductive growth, for certain ranges of the model parameters. In natural systems a predictable vegetative loss burst may be necessary to promote multiple switches.     

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。     

SOYBEAN GROWTH RESPONSES TO ENHANCED LEVELS OF ULTRAVIOLET-B RADIATION UNDER GREENHOUSE CONDITIONS

Soybean (Glycine max [L.] Merr. cv. Essex) was grown in an unshaded greenhouse under three levels of biologically effective ultraviolet-B (UV-B_BE) radiation (effective daily dose: 0, 11.5 and 13.6 kJ m^–2) for 91 days. Plants were harvested at regular intervals beginning 10 days after germination until reproductive maturity. Mathematical growth analysis revealed that the effects of UV-B radiation varied with plant growth stage. The transition period between vegetative and reproductive growth was the most sensitive to UV-B radiation. Intermediate levels of UV-B had deleterious effects on plant height, leaf area, and total plant dry weight at late vegetative and reproductive stages of development. Specific leaf weight increased during vegetative growth but was unaffected by UV-B during reproductive growth stages. Relative growth, net assimilation, and stem elongation rates were decreased by UV-B radiation during vegetative and early reproductive growth stages. Variation in plant responses may be due in part to changes in microclimate within the plant canopy or to differences in repair or protection mechanisms at differing developmental stages.