大吴风草（菊科：千里光族）的核形态及其系统学意义

研究了大吴风草属的核形态,染色体间期为复杂型;前期 色体为中间型,染色体长度从３．７０μm到２．６４μｍ,平均长度为３．２０μｍ;核型公式为２n=60=14m 26sm 20st(4SAT),为３Ａ类型。过去认为大吴风草属与橐吾属接近,并比之原始,但染色体和花粉特征并不支持这种处理。     

大吴风草属、假橐吾属花粉表面纹饰及其分类学意义

观察了千里光族款冬亚族中大吴风草属,假橐吾属及其相关类群5属共8种植物在扫描电镜下的花粉性状,所有种类的花粉外壁均为刺状纹饰,但在刺的长短,刺部是否膨大、刺基膨大上的纹饰以及刺基之间的纹饰等方面存在差别,大吴风草的花粉外壁性状不同于橐吾属,从而不支持它与后者有较近亲缘关系的观点它与花粉超薄结构同为“向日葵型”的多榔菊属的花粉外壁性状也不相同,假橐吾属不同于橐吾属和垂头菊属的花粉外壁性状,研究结果支持本单种属的成立。     

大吴风草叶柄的胚状体诱导和植株再生

植物名称:大吴风草(Farfugium japonicum),又名活血莲、莲蓬草、八角乌。     

菊科千里光簇未冬亚族的花粉超薄结构及其系统学意义

研究了国产菊科千里光族款冬亚族及其相关类群１１属１５种植物的花粉超薄结构。研究类群的花粉超薄结构可分为２类：“千里光型”和“向日葵型”。多榔菊属、大吴风草属和毛冠菊属为“向日葵型”,其余种类均为“千里光型”。根据花粉超薄结构类型,结合其它有关方面的研究,认为大吴风草属与橐吾属并不近缘,而毛冠菊属可能接近于紫菀族。     

画眉草属一新变种

画眉草属一新变种赵南先，马欣堂（安徽省生物研究所，合肥２３００３１）（中国科学院植物研究所，北京１０００９３）关键词画眉草属，福建知风草ＡＮＥＷＶＡＲＩＥＴＹＯＦＥＲＡＧＲＯＳＩＴＩＳ（ＧＲＡＭＩＮＥＡＥ）￥ＺＨＡＯＮａｎ－Ｘｉａｎ；ＭＡＸｉｎ－Ｔａ...     

菊科千里光族款冬亚族的花粉超薄结构及其系统学意义

研究了国产菊科千里光族款冬亚族及其相关类群 1 1属 1 5种植物的花粉超薄结构。研究类群的花粉超薄结构可分为 2类 :“千里光型”和“向日葵型”。多榔菊属、大吴风草属和毛冠菊属为“向日葵型”,其余种类均为“千里光型”。根据花粉超薄结构类型 ,结合其它有关方面的研究 ,认为大吴风草属与橐吾属并不近缘 ,而毛冠菊属可能接近于紫菀族。     

霉草科,缅甸被子植物一新记录科

在近期缅甸北部的植物考察中,一种菌类寄生植物矮生喜荫草(Sciaphila nana Blume)被发现和确认。矮生喜荫草代表缅甸被子植物一新记录科,霉草科植物。矮生喜荫草主要特征为花单性同株、雄花内轮花被片顶端具有柄的门把状物、花被片6、3个雄蕊、花药4室。     

地毯草的光合特性研究

地毯草是一种典型的暖季型草坪草。用Li 6400便携式光合分析仪测定地毯草的光合特性。地毯草的光合日进程呈单峰型,无"午休"现象且受非气孔限制,最大净光合速率出现在14∶00,变化趋势与光合有效辐射(PAR)、气温(Ta)、蒸腾速率(Tr)等因子相同,与空气相对湿度(RH)、胞间CO2浓度(Ci)等相反;其光饱合点超过2000μmol.m 2s 1,最大净光合速率达22μmol.m 2s 1,暗呼吸速率为1.34μmol.m 2s 1,CO2补偿点为0.97μmol.mol 1,光补偿点为22.2μmol.m 2s 1,羧化效率为0.2539μmol.m 2s 1,表观光量子效率高达0.0592μmol.mol 1;表明地毯草是一种具有较强耐荫性的C4型阳性的暖季型草坪草,除了在园林中可以广泛用作草坪地被外还可以在一些较荫湿的特殊地带作为绿化和防护之用。     

中国石灰岩地区霉草科一新记录种——星状霉草

首次报道了中国石灰岩地区霉草科喜荫草属一新记录种--星状霉草Sciaphila stellata Aver.,本种与国产的大柱霉草S.megastyla Fukuyama et Suzuki在外形上较相似,但不同在于前者茎具不明显的棱,叶片苞片状,卵形或三角形,顶端钝,花序仅排列在轴的一侧;雄花与雌花花被片具有明显的差...     

结缕草生物技术研究进展

结缕草属植物具有耐干旱、耐盐和耐践踏等优良特性。最近的研究表明,基因转移与重组技术在结缕草遗传改良中具有巨大应用潜力;结缕草遗传连锁图谱构建取得重要进展;基因克隆和基因资源研究正在展开。结合当前有关结缕草生物技术研究现状,综述了结缕草基因工程和基因资源方面的研究进展,讨论了存在的问题并展望其前景。     

Combined effects of shade and drought on tulip poplar seedlings: trade‐off in tolerance or facilitation?

It has been hypothesised that many natural plant distribution patterns can be explained by a trade-off between shade and drought tolerance which would make plants more sensitive to shade under dry conditions. On the other hand, shading by nurse plants is often observed to enhance growth and survival of smaller plants in dry areas. This paper describes an experiment designed to address the interactive effects of drought and shade on growth and physiology of tulip poplar seedlings ( Liriodendron tulipifera ) grown in shade houses under different combinations of irradiance (1%, 5%, 12%, 17%, and 27% of ambient PAR) and soil water content (5–9%, 11–15%, and>20%). The results show no evidence that higher PAR levels compensate for the negative effects of drought on photosynthesis and growth. Rather, rates of estimated daily shoot carbon gain decreased with PAR under dry conditions. Daily xylem sapflow patterns indicated that this was associated with a strong reduction in stomatal conductance in plants growing in dry soil and high PAR conditions. Whole-shoot light compensation points were higher for plants raised under higher PAR conditions, but were not significantly influenced by the water treatments. Shoot dark respiration rates decreased under drier conditions. These results do not support the hypothesis of a trade-off between shade and drought tolerance. Instead, they indicate mechanisms that can lead to positive effects of shading by neighbouring plants under dry conditions. Indeed, such facilitation is thought to be important in many plant communities.     

Overexpression of phytochrome A and its hyperactive mutant improves shade tolerance and turf quality in creeping bentgrass and zoysiagrass

Phytochrome A (phyA) in higher plants is known to function as a far-red/shade light-sensing photoreceptor in suppressing shade avoidance responses (SARs) to shade stress. In this paper, the Avena PHYA gene was introduced into creeping bentgrass (Agrostis stolonifera L.) and zoysiagrass (Zoysia japonica Steud.) to improve turf quality by suppressing the SARs. In addition to wild-type PHYA, a hyperactive mutant gene (S599A-PHYA), in which a phosphorylation site involved in light-signal attenuation was removed, was also transformed into the turfgrasses. Phenotypic traits of the transgenic plants were compared to assess the suppression of SARs under a simulated shade condition and outdoor field conditions after three growth seasons. Under the shade condition, the S599A-PhyA transgenic creeping bentgrass plants showed shade avoidance-suppressing phenotypes with a 45?% shorter leaf lengths, 24?% shorter internode lengths, and twofold increases in chlorophyll concentrations when compared with control plants. Transgenic zoysiagrass plants overexpressing S599A-PHYA also showed shade-tolerant phenotypes under the shade condition with reductions in leaf length (15?%), internode length (30?%), leaf length/width ratio (19?%) and leaf area (22?%), as well as increases in chlorophyll contents (19?%) and runner lengths (30?%) compared to control plants. The phenotypes of transgenic zoysiagrass were also investigated in dense field habitats, and the transgenic turfgrass exhibited shade-tolerant phenotypes similar to those observed under laboratory shade conditions. Therefore, the present study suggests that the hyperactive phyA is effective for the development of shade-tolerant plants, and that the shade tolerance nature is sustained under field conditions.     

The shrub Rhodomyrtus tomentosa acts as a nurse plant for seedlings differing in shade tolerance in degraded land of South China

Questions: What are the nurse effects of Rhodomyrtus tomentosa in degraded land of South China? Are canopy or soil factors responsible for the main nurse effect? Do facilitative effects increase with the shade tolerance of the target species? Location: Degraded shrubland in South China. Methods: Seedlings of three native climax woody species (Schima superba, Michelia macclurei, Castanopsis fissa) that differ in shade tolerance were subjected to four treatments by transplantation: (1) under the canopy of R. tomentosa shrubs; (2) in open interspaces without vegetation cover (control); (3) under the canopy of R. tomentosa from which canopies had been removed; and (4) in open interspaces without vegetation but covered by branches and leaves of R. tomentosa. Results: At low soil nutrient levels, increased canopy shade, soil porosity and soil moisture under the canopy of R. tomentosa increased seedling survival of the climax tree species S. superba, C. fissa and M. macclurei, and shoot height of S. superba. The nurse effect (a form of facilitation) of R. tomentosa depended more on canopy shade than on soil amelioration. The magnitude of facilitation or nurse effect was positively correlated with shade tolerance of the target species. Conclusions: Use of nurse plants in restoration differs from traditional reforestation (clearing and/or burning to reduce interspecific competition between target tree species and non‐target species) because it focuses on positive interactions between nurse plants and target plants that increase establishment of target species and reduce time required for restoration. Because nurse effects of R. tomentosa shrubs tended to be larger on target species with greater shade tolerance, shade‐tolerant plants are suggested as target species to accelerate restoration.     

Light environment,sapling architecture,and leaf display in six rain forest tree species

Architecture and leaf display were compared in saplings of six rain forest tree species differing in shade tolerance. Saplings were selected along the whole light range encountered in a forest environment. Species differed largely in realized height and crown expansion per unit support biomass, but this could not be related to differences in shade tolerance. The results demonstrate that there exist various solutions to an effective expansion of plant height and crown area. It is argued that choice of the study species and the ontogenetic trajectory regarded determine to a large extent the outcome of interspecific comparisons. No evidence was found that pioneers were characterized by a multilayered and shade tolerants by a monolayered leaf distribution. Yet, sun plants had a similar crown area, a deeper crown, and a higher leaf area index compared to shade plants and their leaves were more evenly distributed along the stem. This suggests that differences in leaf layering are found between plants growing in different light environments, rather than between species differing in shade tolerance.     

森林植物耐荫性及其形态和生理适应性研究进展

耐荫性是植物在低光环境下的生存和生长能力,对森林植物群落演替起重要作用,植物对遮荫的适应机制已成为生态学的研究热点.本文综述了森林植物的耐荫性及其在形态和生理方面的适应性,分析了森林植物在生长性状、生物量分配、树冠结构、叶片形态生理、叶片解剖结构、光合参数、碳水化合物分配、水分和养分的利用等方面对遮荫产生的可塑性响应,最后对目前研究存在的问题进行了分析,展望了未来的研究内容和方向.     

Shedding light on shade: ecological perspectives of understorey plant life

Shade, in ecological sense, is not merely a lack of light, but a multi-faceted phenomenon that creates new and complex settings for community and ecosystem dynamics. Tolerating shade therefore affects plants’ ability to cope with other stressors, and also shape its interactions with surrounding organisms. The aim of this broad review was to map our current knowledge about how shade affects plants, plant communities and ecosystems – to gather together knowledge of what we know, but also to point out what we do not yet know. This review covers the following topics: the nature of shade, and ecological and physiological complexities related to growing under a canopy; plants’ capability of tolerating other stress factors while living under a shade – resource trade-offs and polytolerance of abiotic stress; ontogenetic effects of shade tolerance; coexistence patterns under the canopy – how shade determines the forest structure and diversity; shade-induced abiotic dynamics in understorey vegetation, including changing patterns of irradiance, temperature and humidity under the canopy; shade-driven plant–plant and plant–animal interactions – how shade mediates facilitation and stress, and how it creates differentiated environment for different herbivores and pollinators, including the role of volatile organic compounds. We also discuss the ways how vegetation in understorey environments will be affected by climate change, as shade might play a significant role in mitigating negative effects of climate change. Our review shows that living under a shade affects biotic and abiotic stress tolerance of plants, it also influences the outcomes of both symbiotic and competitive plant–plant and plant–animal interactions in a complex and dynamic manner. The current knowledge of shade-related mechanisms is rather ample, however there is much room for progress in integrating different implications of the multifaceted nature of shade into consistent and integral understanding how communities and ecosystems function.     

Neighbour signals perceived by phytochrome B increase thermotolerance in Arabidopsis

Due to the preeminence of reductionist approaches, understanding of plant responses to combined stresses is limited. We speculated that light‐quality signals of neighbouring vegetation might increase susceptibility to heat shocks because shade reduces tissue temperature and hence the likeness of heat shocks. In contrast, plants of Arabidopsis thaliana grown under low‐red/far‐red ratios typical of shade were less damaged by heat stress than plants grown under simulated sunlight. Neighbour signals reduce the activity of phytochrome B (phyB), increasing the abundance of PHYTOCHROME‐INTERACTING FACTORS (PIFs). The phyB mutant showed high tolerance to heat stress even under simulated sunlight, and a pif multiple mutant showed low tolerance under simulated shade. phyB and red/far‐red ratio had no effects on seedlings acclimated with nonstressful warm temperatures before the heat shock. The phyB mutant showed reduced expression of several fatty acid desaturase (FAD) genes and less proportion of fully unsaturated fatty acids and electrolyte leakage of membranes exposed to heat shocks. Red‐light‐activated phyB also reduced thermotolerance of dark‐grown seedlings but not via changes in FADs expression and membrane stability. We propose that the reduced photosynthetic capacity linked to thermotolerant membranes would be less costly under shade, where the light input limits photosynthesis.     

Costs versus risks: Architectural changes with changing light quantity and quality in saplings of temperate rainforest trees of different shade tolerance

Light requirements and functional strategies of plants to cope with light heterogeneity in the field have a strong influence on community structure and dynamics. Shade intolerant plants often show a shade avoidance strategy involving a phytochrome‐mediated stem elongation in response to changes in red : far red ratio, while shade‐tolerant plants typically harvest light very efficiently. We measured plant size, stem diameter, internode and leaf lengths in randomly chosen saplings of 11 woody species differing in their shade tolerance in both a secondary forest and an old‐growth temperate evergreen rainforest in southern Chile. We also recorded the irradiance spectrum and the diffuse and direct light availabilities at each sampling point. Significant differences were found for the mean light environment of the saplings of each species, which also differed in basal stem diameter, internode length and leaf length, but not in plant height. Both plant slenderness (plant height/stem diameter) and mean internode length increased with increasing light availability, but no relationship was found between any of these two traits and red : far red ratio. The change in plant slenderness with light availability was of lesser magnitude with increasing shade tolerance of the species, while internode change with light availability increased with increasing shade tolerance of the species. Shade tolerators afford higher costs (thicker stems and plants), which render more biomechanically robust plants, and respond more to the light environment in a trait strongly influencing light interception (internode length) than shade intolerant species. By contrast, less shade‐tolerant plants afforded higher risks with a plastic response to escape from the understorey by making thinner plants that were biomechanically weaker and poorer light interceptors. Thus, species differing in their shade tolerances do differ in their plastic responses to light. Our results contribute to explain plant coexistence in heterogeneous light environments by improving our mechanistic understanding of species responses to light.     

植株叶片的光合色素构成对遮阴的响应

叶绿素在植株体内负责光能的吸收、传递和转化, 类胡萝卜素则行使光能捕获和光破坏防御两大功能, 它们在光合作用中起着非常重要的作用。该文综述了几大主要光合色素的分布和功能, 以及不同物种的色素含量和构成差异。阳生植物的叶黄素库较大, 但脱环氧化水平不及阴生植物。黄体素与叶黄素库的比值与植物的耐阴性呈正相关关系。由不同的遮阴源造成的遮阴环境, 光强和光质有很大的差异, 总体来说对植物生长的影响, 建筑物遮阴<阔叶林遮阴<针叶林遮阴。光强的改变可诱导类胡萝卜素的两大循环——叶黄素循环和黄体素循环。由光强诱导的叶绿素含量和叶绿素a/b比值的改变与该物种的耐阴性无关。短时间的遮阴不会对植物的生长造成危害, 叶黄素库的大小不仅与每天接受的光量子有关, 更与光量子在一天的分布有关, 因为光照和温度是协同作用的。光合作用或色素构成是蓝光、红光和远红光共同作用的结果, 不是某一种单色光所能替代的。我们总结了影响植物色素构成的内因和外因, 指出植物主要通过调整光反应中心和捕光天线色素蛋白复合体的比例, 以及两个光系统的比值来调整色素含量和构成以适应不同的光照条件, 提出了现存研究中存在的一些问题, 旨在为今后的相关研究提供建议。     

An Analysis of Growth of Oil Palm Seedlings in Full Daylight and in Shade

Growth of seedling oil palms (Elaeis guineensis), in full daylightand under three levels of shade, was studied using growth analysistechniques. In full day-light, net assimilation rates (E_A) betweeno.15 and 0.32 g./dm.²/week were obtained associated with lowleaf-area ratios (F) giving relative growth-rates (R_W) rangingfromI I.8 to 3.2 per cent, per day. There were no indicationsof seasonal differences within the small range of values found. The plants take about 90 days to adapt to shade conditions becausethe mean plastochron is 24 days, and shading effects are beststudied on plants grown since germination under the shade treatments.Very different pictures of response to shade were obtained usingplants grown initially in full light followed by 90 days' shadebefore sampling compared with plants grown under shade sincegermination. In the latter, except at the lowest light levelused, I I.I per cent, of full day-light, there was very littleeffect of light on E_A or R_w, although the F values decreasedas light increased. Extrapolation of the F values to the extinctionpoint gave values similar to those obtained in another experimenton the effect of a number of shade levels on F. The physiological and ecological implications of these findings,particularly the low growth-rates and shade tolerance, are discussed.