濒危植物明党参种子散布和种子库动态研究

对伞形科濒危植物明党参（Changium smyrnioides)的种子生产、散布和种子库动态进行了研究。明党参平均每株产生完好种子132粒,86.36%来自顶生花序,不同生境中个体产生的种子千粒重有差异;其平均1.06m高的花葶在种子散布过程中易倒伏,使种子远离母株;种子散布格局为聚集型;种子库密度随时间逐渐下降。明党参种子产量和不同时期种子库密度均低于同科非濒危植物峨参（Anthriscus sylvestris),2个种的种子库均为非持续型;明党参具有低种子数、大粒种子、种子散布远离母株以减少种内竞争的K对策,在受到人类大量采挖和生境干扰后种群不容易迅速恢复;而峨参采取高种子数、小粒种子、种子近母株密集分布和产生无性系的r对策,种群受干扰后易恢复。     

三峡地区柏木种子萌发和幼苗更新的研究

对三峡地区柏木(Cupressus funebris)林柏木种子的萌发、幼苗存活、幼苗生长进行了研究.结果表明,(1)柏木种子的萌动期约为10 d,播种35-45 d后进入萌发高峰期,柏木种子的平均萌发率为47.7%.土壤基质对种子萌发的影响是极显著的,光照对萌发则没有显著的影响.(2)幼苗平均死亡率为52.6%.土壤类型和光照强度对幼苗的存活都有显著影响,在林下土和80%光照条件下幼苗的存活率最高.(3)柏木幼苗生长初期茎的生长动态呈\"S\"型,而叶片数量的增长动态近于直线型.幼苗生长初期生物量形成主要受光照条件的影响,土壤类型的影响不显著.土壤和光照条件对柏木林柏木幼苗的更新都有显著影响,但是土壤条件主要影响种子萌发和幼苗的存活,而光照条件则主要对幼苗的生长和存活产生影响.     

珍稀濒危植物蒜头果种子萌发特征与幼苗类型的研究

以去除果皮后阴干的珍稀濒危植物蒜头果种子为材料,在温室大棚沙池内进行层积处理,从层积处理开始至子叶出土的不同萌发阶段,考察蒜头果种子发育形态、贮藏物质积累、酶活性以及幼苗类型等变化特征,初步探讨其种子休眠形成原因。结果显示：(1)蒜头果种子从解除休眠开始至萌发形成幼苗的过程约需195 d,其中幼胚的形态发育后熟约需75 d,随后30 d内是种子集中萌发的时期,其发芽率达到最高(53.33%);依据种胚发育形态的标志特征将此过程划分为7个阶段(S1～S7阶段):S1阶段种子未萌发,S2阶段种胚“露白”,S3阶段胚根突破种皮长超过1 cm, S4阶段下胚轴与胚根连接处形成弯钩结构,S5阶段“S”型胚形成及胚根前端膨大,S6阶段种子不仅具有膨大的胚根且已有侧根的分化,S7阶段子叶脱落,胚芽出土,真叶出现。(2)蒜头果种子在湿沙层积过程中,种胚胚长和胚率从S1阶段的(5.49±1.57)mm和(19.48±5.72)%分别增加至S6阶段的(67.92±2.94)mm和(240.75±15.29)%,胚率平均增加了12.4倍,显示蒜头果种子的胚需要经历后熟过程才能萌发,属于胚后熟型种子。(3)从...     

濒危植物银杉种子特征的研究

同一株银杉的不同珠果的出种量没有明显差异,说明就同一植株而言,其有性生殖是同步,球果的发育程度比较接近。银杉种子的平均重量０．００１９７ｇ,仅为乔木树种种子平均重量的６％。种子中空粒比例达１６．２４％,反映出较高的种子败育率,饱满的种子中有生活力者仅占５３．５％,银杉种子的吸水过程有３个明显的阶段,０－１ｈ是急剧吸水阶段,１－９ｈ吸水基本停滞９ｈ到１４ｄ吸水果又呈递增趋势。在同样贮藏条件下,播种环     

磺胺对小麦种子萌发和幼苗生长的影响

初步探讨了磺胺对小麦种子萌发与幼苗生长的影响。研究表明,用低浓度（＜6.0mg/L)的磺胺溶液浸泡小麦种子,能显著增加幼苗的根重,根长和根冠比,提高根系活力和叶片叶绿素的含量,降低幼苗的苗高,苗重,但对发芽率影响不大。高浓度（＞10．0mg/L)和安则强烈抑制小麦幼苗根,芽的生长,并导致幼苗形态的不良变化。     

南亚热带常绿阔叶林几个树种的种子萌发和幼苗发育

南亚热带常绿阔叶林树种光叶红豆（Ｏｒｍ ｏｓｉａ ｇｌａｂｅｒｒｉｍ ａ Ｗｕ）、扁斗青冈（Ｑｕｅｒｃｕｓ ｈｕｉＣｈｕｎ）、罗浮柿（Ｄｉｏｓｐｙｒｏｓ ｍｏｒｒｉｓｉａｎａ Ｈａｎｃｅ）和阳性速生树种木蝴蝶（Ｏｒｏｘｙｌｕｍ ｉｎｄｉｃｕｍ （Ｌ．）Ｖｅｎｔ．）、香椿（Ｔｏｏｎａ ｓｉｎｅｎｓｉｓ （Ａ． Ｔｕｓｓ．） Ｒｏｅｍ ．）和泡桐（Ｐａｕｌｏｗ ｎｉａ ｆｏｒｔｕｎｅｉ（Ｓｅｅｍ ．） Ｈｅｍ －ｓｌ．）的种子中,除光叶红豆外都为迅速萌发,处理２—３ ｄ 便开始萌发,２—４周萌发完全。光叶红豆因种皮特性而延迟萌发,切破种皮即能迅速萌发。速生树种的萌发较快。森林树种和阳性速生树种木蝴蝶、香椿在光、暗下均能萌发,种子微小的速生树种泡桐则几乎只在光下萌发。种子萌发过程中吸水显示出３个阶段,不同种有所不同。幼苗的形态可能和耐阴性和生长速度有关。在暗中,光叶红豆能形成正常的叶,植株不徒长,其它种不能形成正常的幼苗,植株徒长,不形成叶子（或仅有黄色的子叶）。森林树种的幼苗生长较慢。     

珍稀油料树种琴叶风吹楠果实和种子形态变异

以云南野生琴叶风吹楠(Horsfieldia pandurifolia)为材料,对39株树的果实和种子的形态进行变异分析。结果表明,果实和种子形态指标株间变异大,株内变异小。单株间果实表现出从卵圆形至长椭圆形的变异,果长4~7 cm,先端圆钝至锐尖,基部不同程度偏斜,与文献记录差异较大;单株间种子形态表现出从卵形、长卵形至细长形或近锥形的变异。单株平均种长变幅为25.05~35.66 mm,种宽为13.30~19.62 mm,长宽比为1.47~2.32,单因素方差分析表明此3个性状单株间差异极显著(p<0.01)。灰白色种皮具褐色斑块,种脐和胚位于种子基部,种子先端突尖或具短喙是稳定的性状,有重要的分类学价值。     

热带雨林林内小生境对木奶果和染木种子萌发与幼苗存活的影响

森林生态系统中小生境的差异可能影响种子萌发与幼苗的建立,并形成物种不同的分布格局。为探讨生境异质性对植物分布的影响,该研究在西双版纳热带季节性雨林中选取5个具有不同海拔和地形的小生境,人工散布木奶果与染木种子,定期监测种子萌发与幼苗存活,同步记录小生境的近地面（距地面3 cm）温度、近地面(3 cm)空气湿度和表层土壤(5 cm)含水量变化,并在实验室开展种子脱水和不同水势条件下的种子萌发实验。结果表明：（1）实验所选的5个小生境中,沟底地带的土壤水分含量在一年中始终都高于其他小生境;5个小生境的空气相对湿度在雨季与雾凉季都接近饱和,只有在干热季出现明显的差别,即随海拔的升高,空气湿度下降。同时,在旱季,近地面温度随海拔的升高而升高, 出现1~2个月的山地逆温现象。（2）木奶果与染木具有不同的种子传播与萌发规律,而且染木种子在不同生境下,其种子萌发率和幼苗存活率有显著的差异。其中：木奶果种子在雨季成熟散布并快速萌发,以幼苗的形式度过干热季,其种子可以在相对较低的水势下萌发;染木种子在雨季末期成熟并进入休眠期,以种子的形式度过干热季,其种子相对较抗脱水。研究认为,地形是决定西双版纳热带季节性雨林生境异质性的重要因子,小生境在温度和水分方面的差异在干热季时尤为明显,并对木奶果和染木种子的萌发或幼苗存活产生了重要影响, 而木奶果与染木种子自身的特性使其对于西双版纳季节性的干旱具有不同的适应对策。     

种子生态学: 种子在群落中的作用

种子是指由胚珠发育而成的繁殖器官。在生态学研究中,其涵义要比植物学上种子的概念宽泛有时也指果实。作为种子植物生活史的一个重要阶段,种子从其发生、发育到成熟、传播、萌发以至成苗都与周围的环境紧密联系着。因而种子生态学是研究种子与其环境相互关系的科学。种子生态学的研究内容主要包括:种子发育与成熟的环境调节(生殖分配和结实格局)、种子性状、种子捕食、种子传播(包括种子雨)、种子库、种子休眠、种子萌发、幼苗建成和种群更新等,其中种子传播、土壤种子库、种子休眠与萌发是研究的核心内容。     

喀斯特乡土树种伊桐的种实性状及幼苗生长特征

研究了喀斯特乡土树种伊桐的果实性状、种子性状、播种萌发和幼苗生长等的基本特征.结果表明:伊桐果实单果鲜重63.20～149.50 g,其长度和宽度则分别为55.59～86.60mm和38.59～51.80mm,单果出种量19.95～57.15 g,出籽率31.57％～40.81％,单果种子数343～690粒,单粒种子均重0.0582～0.0857 g,其出籽率、单果种子数和单粒种子均重与果实重量存在一定程度的正相关;伊桐种子的长、宽平均分别为(25.93±2.80)mm和(13.72±2.88)mm,完整种子平均风干重(0.0153±0.0033)g,脱翅种子平均重(0.0112±0.0024)g,种翅占整个种子的(26.56±4.53)％;伊桐种子播前采取不同处理方式的平均发芽天数、平均发芽指数和平均发芽率等存在一定或是比较明显的差异,浸种、脱翅或两者相结合的方式均能有效缩短种子发芽时间并明显提高种子发芽率;伊桐幼苗的株高和基径的月均生长量分别介于3.3～16.3 cm和0.32～2.80mm之间,其中经浸种处理的前期生长较快,未经浸种处理的中期生长较快.     

Reproductive ecology of Thymelaea velutina (Thymelaeaceae)- Factors contributing to the maintenance of heterocarpy

Thymelaea velutina (Thymelaeaceae) is a dioecious shrub that presents a unique type of heterocarpy which consists of the simultaneous production of dry and fleshy fruits. It is endemic to the Balearic Islands (Western Mediterranean) and is found both in dunes and mountain areas. The goal of this study was to identify which factors influence the production of both fruit types, examining the variation of their effects at a spatio-temporal scale (comparing two localities in different years). Specifically, we investigated (1) whether pollen limitation influences the type of fruit produced, and (2) the possible differences in seed size, mass, dispersal capacity, seed predation, germination patterns and seedling survival between fruit types. We also examined if the production of fleshy fruits was modified with the application of gibberellins to reproductive branches. Although fleshy fruits were consistently more abundant than dry ones at both populations, their proportion was significantly higher at the site with greater precipitation. The addition of either pollen or gibberellins did not affect the proportion of each fruit type. Seeds in fleshy fruits are consistently larger, heavier and more likely to be dispersed than seeds in dry fruits, but germinability, germination rate and seedling survival was similar among fruit types. Heterocarpy in this species is currently maintained as there is no apparent factor that exerts any strong selective pressure on either fruit type. The two fruit types might even have different `functions', one serving especially for dispersal and population expansion and the other for producing a seed bank that ensures an eventual germination.     

Fruit colour polymorphism in Acacia ligulata: seed and seedling performance, clinal patterns, and chemical variation

Fruit colour polymorphisms are widespread in nature, but their ecological and evolutionary dynamics remain poorly understood. Here we examine Acacia ligulata, a shrub of the Australian arid zone which exhibits a red/orange/yellow aril colour polymorphism. We asked whether the polymorphism had a genetic basis; whether selection acted differentially on morphs during the seed and seedling stages; whether geographic variation in morph frequencies was correlated with environmental factors; and whether morphs differed in physical or chemical characteristics that might influence selection on them. When grown to maturity in a common greenhouse environment, maternal families of seeds showed phenotypic patterns consistent with biparental genetic control of the polymorphism. In contrast to other fruit-colour polymorphic species, progeny of A. ligulata morphs did not vary in rates of seedling emergence or survival in a common garden. Sampling along a 580 km transect revealed clinal variation in morph frequencies. Frequencies of the yellow morph decreased, and frequencies of the red morph increased, across a gradient of decreasing temperature and increasing rainfall. Morphs did not differ in seed mass, aril mass, or in profiles of fatty acids and flavonoids in either arils or seeds. However, morphs showed consistent differences in carotenoid profiles' and elemental content of arils, suggesting that selection by avian and insect seed dispersers, seed predators and herbivores should be investigated. These patterns indicate that both abiotic and biotic factors may contribute to selection on the A. ligulata polymorphism. This revised version was published online in August 2006 with corrections to the Cover Date.     

The role of the brown-eared bulbulHypsypetes amaurotis as a seed dispersal agent

The role of the brown-eared bulbul,Hypsypetes amaurotis, as a dispersal agent for seeds of fruiting plants was studied by field observations for two years, in parallel with laboratory experiments on seed germination. Bulbuls consumed fruits of 53 species from 24 plant families. The fruits of these plants had similar color and size, and these characteristics were likely to enhance the feeding efficiency of the frugivore. Laboratory experiments on 20 food plant species demonstrated that: (1) no seeds were injured by passing through the bulbul's gut; (2) seeds that had passed through the bulbul's gut were still able to germinate and (3) fruit pulp reduced germination ability. When pulp was removed by passing through bulbul's gut, or by hand, germination was improved. An estimate of the home range of six bulbuls suggested that they may transport seeds for at least 300 m.