土施多效唑对小桐子营养生长与生殖生长的影响

小桐子(Jatropha curcas)是一种具有多种用途的植物,其种子含油量高达40％,是一种很有应用前景的能源植物.小桐子在温度、湿度较高的地区,特别是其修剪后新萌发的枝条经常出现营养生长旺盛,成花量较少的现象,导致其种子产量较低.本研究采用多效唑(paclobutrazol,PAC)对小桐子进行土施处理,结果表明:多效唑的使用剂量为0.8g·m-1树冠直径时,可有效抑制小桐子的营养生长,降低株高;同时促进小桐子的生殖生长,增加开花和结果枝条数量,增加花序和果序数量,增加单个花序的总花数和雌花的比例,可将小桐子单株种子产量提高2.4倍.此外,多效唑处理使小桐子的开花期和结果期更加集中,便于田间管理和采收.多效唑作为赤霉素合成的抑制剂,可以有效地促进小桐子由营养生长向生殖生长的转变,对于了解赤霉素在调控小桐子花发育方面的作用具有重要意义;同时也有助于克隆有关功能基因,进一步采用转基因技术对小桐子进行遗传改良.     

小桐子花的性别与开花时间的相互关系

通过对小桐子(Jatropha curcas L.)花序上小花的开花顺序和小花性别的观察,发现其聚伞花序中心花的性别与其开花时间相关联,同时还和周围其它小花的性别有很大的相关性.中心花若在整个花序开花的第一天开放,仅有23.2%的可能是雌花;若在第二天及以后开放,有85%以上的可能为雌花.而中心花的性别又与其它花的性别相关,中心花如为雌花,那么聚伞花序上的其它小花有80%的可能性为雌花;但中心花若为雄花,那么整个聚伞花序上将不会再有雌花.研究小桐子的开花行为及性别控制规律,对于进一步人工调控小桐子花的性别表达,提高小桐子的产量、培育高产稳产品种,具有重要的应用价值.     

与小桐子雌花形成、雌雄花比例提高相关影响因素的研究进展

小桐子是重要的能源植物,由于它是雌雄同株植物,雌花少,雄花多,雌雄花比例低,因而导致其种子产量很低,严重制约了其产业化进程。因此,了解与小桐子雌花形成、雌雄花比例提高相关影响因素的研究进展,不但对种植者进行小桐子大田种植采取必要的栽培措施具有指导意义,而且也为下一步开展相关的研究工作指明了方向。为此,综述了与小桐子单性花性别分化相关影响因素的研究进展,并对该领域未来的研究重点作了展望。与小桐子雌花形成、雌雄花比例提高相关的影响因素既有内因,也有外因,内因有开花习性、植物激素、遗传基因和结果枝的年龄与大小;外因包括植物生长调节剂、立地环境、CO2浓度、光照、水份、土壤厚度、所施肥料等环境因素。其中,最重要的影响因素是植物激素和遗传基因,二者协同作用共同调控小桐子的性别分化。     

珍珠莲传粉系统的研究

珍珠莲为榕属攀援灌木,雌雄异株。雌花序中着生雌花,每个花序中平均有雌花310.4朵;雄花序中着生瘿花、雄花和两性花,每个花序平均有瘿花391.0朵、雄花104.8朵、两性花2.0朵。自然状态下雌、瘿花的结实率和成虫瘿率分别为95.88％、29.51％。雌、瘿花在生理上已完全分离。匍茎榕小蜂是唯一能进入花产卵或传粉的共生昆虫,二者构成的传粉系统依靠形态结构的高度互适,物候生活史的相互吻合,以及特化的生物学行为维系其专一性和稳固性。     

赤霉素、钙和甜菜碱对小桐子种子萌发及幼苗抗低温和干旱的影响

小桐子(Jatropha curcas L.)属大戟科( Euphorbiaceae)麻疯树属(Jatropha L.)的能源植物。分别以小桐子种子和幼苗为实验材料,研究了不同浓度的赤霉素和CaCl₂单独处理,以及不同浓度的赤霉素、CaCl₂和甜菜碱组合处理对小桐子种子萌发及幼苗抗低温和干旱的影响。结果表明:分别用10 mg/L赤霉素和10 mmol/L CaCl₂处理小桐子种子,不仅可以提高其在正常萌发条件(26℃)、低温(18℃)和干旱胁迫(5% PEG6000)下的发芽率,还可缓解小桐子幼苗在低温(2℃)或干旱胁迫(25% PEG6000)下电解质渗漏率的增加和丙二醛(MDA)的积累。用10 mg/L赤霉素、5 mmol/L CaCl₂和15 mmol/L甜菜碱组合处理小桐子种子,也可进一步增强其在正常萌发(26℃)、低温(18℃)和干旱胁迫(5% PEG6000)条件下种子的发芽率,以及缓解小桐子幼苗在低温(2℃)或干旱胁迫(25% PEG6000)下电解质渗漏率的增加和MDA的积累,表明10 mg/L赤霉素和10 mmol/L CaCl₂分别处理或10 mg/L赤霉素、5 mmol/L CaCl₂和10 mmol/L甜菜碱组合处理可提高小桐子种子在低温和干旱胁迫下的发芽率,以及提高小桐子幼苗对低温和干旱胁迫的抵抗能力。     

爱玉子花的变异类型及其相关统计分析

该文报道了爱玉子(Ficus awkeotsang)花序中存在变异花的现象, 并通过花序解剖观测及数据统计分析方法, 研究比较雌、雄花序中变异花的类型、不同品系的花序变异率以及单花序中变异花的数量, 了解变异花发育过程、变异花与传粉小蜂之间的相互关系, 以及变异花对爱玉子产量造成的影响。结果表明: 爱玉子变异花在形态上有单生与伞形花序状2种类型, 雌花序中的变异花分布在雌花区和退化花区; 雄花序中的变异花均生长在瘿花区。雌花序中伞形花序状的A型变异花影响传粉小蜂对正常雌花的授粉, 与正常雌花争夺养分和生长空间从而影响正常雌花的生长发育, 大量A型变异花的存在使未授粉的雌花序延迟凋落或挂树不落, 造成养分流失。雌性品系太和6、太7、W13、乐野8、日野20和大洋Z106的花序中A型变异花数量较多, 对产量有一定的影响。除A型外的其它类型的变异花, 由于数量少且结构简单, 或发育后熟, 对传粉小蜂的传粉、产卵以及花序的发育、成熟没有显著影响。无论是雌性品系还是雄性品系, 以扦插苗繁殖方式形成的植株, 其花序变异率高于以实生苗繁殖方式形成的植株。以上研究结果为高产优质爱玉子品系的选育提供了一定的依据, 且对于爱玉子的栽培和推广有着重要的指导意义。     

爱玉子花的变异类型及其相关统计分析

该文报道了爱玉子（Ficusawkeotsang）花序中存在变异花的现象,并通过花序解剖观测及数据统计分析方法,研究比较雌、雄花序中变异花的类型、不同品系的花序变异率以及单花序中变异花的数量,了解变异花发育过程、变异花与传粉小蜂之间的相互关系,以及变异花对爱玉子产量造成的影响。结果表明：爱玉子变异花在形态上有单生与伞形花序状2种类型,雌花序中的变异花分布在雌花区和退化花区：雄花序中的变异花均生长在瘿花区。雌花序中伞形花序状的A型变异花影响传粉小蜂对正常雌花的授粉,与正常雌花争夺养分和生长空间从而影响正常雌花的生长发育,大量A型变异花的存在使未授粉的雌花序延迟凋落或挂树不落,造成养分流失。雌性品系太和6、太7、W13、乐野8、日野20和大洋Z106的花序中A型变异花数量较多,对产量有一定的影响。除A型外的其它类型的变异花,由于数量少且结构简单,或发育后熟,对传粉小蜂的传粉、产卵以及花序的发育、成熟没有显著影响。无论是雌性品系还是雄性品系,以扦插苗繁殖方式形成的植株,其花序变异率高于以实生苗繁殖方式形成的植株。以上研究结果为高产优质爱玉子品系的选育提供了一定的依据,且对于爱玉子的栽培和推广有着重要的指导意义。     

花叶芋(天南星科)的花器官发生

利用扫描电镜首次观察了天南星科花叶芋(Colocasia bicolor) 的花器官发生过程。花叶芋的肉穗花序由无花被的单性花构成, 雌花发生于花序基部, 雄花发生于花序上部, 中性花位于花序中间部位。雄花: 3 或4 个初生雄蕊原基轮状发生, 随后每个初生原基一分为二, 形成6或8个次生原基; 一部分次生原基在其后的发育过程中融合, 形成5 或7 枚雄蕊; 雄花发育过程中未见雌性结构的分化; 花药的分化先于花丝; 雄蕊合生成雄蕊柱。雌花: 合生心皮, 3或4个心皮原基轮状发生, 未见雄性结构的分化。中性花来源于雌雄花序过渡带上, 属于雄蕊原基的滞后发育以及发育成熟过程中的退化; 与彩叶芋属(Caladium)不同, 此过渡区未见畸形两性花。初生雄蕊原基二裂产生次生原基的次生现象在目前天南星科花器官发生中显得比较特殊, 同时初步探讨了次生原基的融合方式。     

桤木属花序和花的形态发生

在扫描电镜下首次观察了桦木科Betulaceae桤木属Alnus花序和花的形态发生过程,为桦木科属级鉴定提供了微形态学依据.实验材料为东北桤木A.mandshurica和辽东桤木A.sibirica,其雌花序均为柔荑状,由多个小聚伞花序螺旋状排列组成:每个小花序外具1枚初级苞片、2枚次级苞片、2枚三级苞片,内有2朵花.每个花具1个二心皮合生雌蕊,雌蕊具二叉分枝的长柱状花柱.每个小花序的2个二心皮合生雌蕊的定位方式为相互垂直.东北桤木的雌花序由芽鳞包被越冬,而辽东桤木的雌花序裸露越冬.东北桤木和辽东桤木的雄花序亦为柔荑状,由多个小聚伞花序螺旋状排列组成.每个小花序外被1枚初级苞片、2枚次级苞片、2枚三级苞片,内有3朵花.先形成的2枚次级苞片和后形成的2枚三级苞片均来源于小花序原基.3个花原基中.位于中间的比两侧的分化要早.每个花具4枚被片和4枚雄蕊,每个雄蕊具4个药囊.花的被片比雄蕊发育得早,均由花原基发育而成.东北桤木和辽东桤木的雄花序均裸露越冬.     

毛翠雀花花序内的性分配和繁殖成功

两性花植物花序内不同位置的性分配和繁殖成功一般存在差异,通常认为资源竞争、结构效应和交配环境是形成这种差异的主要原因。为了研究雄性和雌性繁殖资源在花序内不同位置间的最优分配问题,该文以青藏高原高寒草甸典型高山植物毛翠雀花为材料,通过比较花序内不同位置的花部特征和种子性状,对其花序内的性分配模式和雌性繁殖成功进行研究,并通过观察传粉者运动特点以及人工去花和补授花粉实验,探讨花序内资源竞争和交配环境对繁殖资源分配的影响。结果表明:(1)不同位置间的雄蕊数、雄蕊鲜重/雌蕊鲜重、花粉数及花粉胚珠比从花序基部到上部显著增加,而雌蕊鲜重和胚珠数逐渐减少,表现出上部花偏雄的性分配;上部花的结籽率显著低于基部花和中部花,不同位置间的发育种子数/果实和发育种子重/果实随着花位置的升高而显著降低,说明基部花具有更佳的雌性繁殖成效。(2)去花处理后,剩余果实的单个种子重/果实显著增加,但发育种子数/果实没有显著增加;而给上部花人工补授异花花粉后,位置间结籽率的差异消失,说明传粉限制而非资源竞争导致了花序内位置依赖的种子生产模式。(3)毛翠雀花雄性先熟的开花特征,以及传粉者苏氏熊蜂从花序基部到上部的定向访花行为,导致了花序内交配环境的变化。综上结果表明,毛翠雀花花序内的性分配和繁殖成功差异是对交配环境适应的结果,对其在高山环境中实现雌雄适合度最优化具有重要意义。     

Benzyladenine Treatment Significantly Increases the Seed Yield of the Biofuel Plant Jatropha curcas

Jatropha curcas, a monoecious perennial biofuel shrub belonging to the family Euphorbiaceae, has few female flowers, which is one of the most important reasons for its poor seed yield. This study was undertaken to determine the effects of the plant growth regulator 6-benzyladenine (BA) on floral development and floral sex determination of J. curcas. Exogenous application of BA significantly increased the total number of flowers per inflorescence, reaching a 3.6-fold increase (from 215 to 784) at 160 mg/l of BA. Furthermore, BA treatments induced bisexual flowers, which were not found in control inflorescences, and a substantial increase in the female-to-male flower ratio. Consequently, a 4.5-fold increase in fruit number and a 3.3-fold increase in final seed yield were observed in inflorescences treated with 160 mg/L of BA, which resulted from the greater number of female flowers and the newly induced bisexual flowers in BA-treated inflorescences. This study indicates that the seed yield of J. curcas can be increased by manipulation of floral development and floral sex expression.     

Differential self‐fertilization rates in response to variation in floral traits within inflorescences of Aquilegia buergeriana var. oxysepala (Ranunculaceae)

To assess variation in the proportion of self‐fertilized seeds among flowers within inflorescences and the relationship between floral traits and the rate of self‐fertilization, the proportion of self‐fertilized seeds among individual flowers was estimated using ten microsatellite markers in self‐compatible plants of Aquilegia buergeriana var. oxysepala. Within‐inflorescence variation in floral traits, such as the duration of the male and female phases, flower size, herkogamy and the number of pollen grains and ovules in two natural populations, were investigated. The first flower in an inflorescence produced more seeds and a higher proportion of self‐fertilized seeds than the second flower. The higher proportion of self‐fertilized seeds in the first flowers was accompanied by a higher number of pollen grains and ovules in the bud stage and the female phase. These results indicate that the high proportion of self‐fertilized seeds in the first flowers in an inflorescence may be due to the high number of remaining pollen grains in the female phase. This suggests that variation in floral traits within inflorescences affects seed quality and quantity among flowers within inflorescences.     

Conservation of microRNA-mediated regulatory networks in response to copper stress in grapevine

Jatropha curcas L. as a bio energy plant belonging to the Euphorbiaceae family is gaining progressive importance over the last years. In 2012 and 2014 field experiments were carried out to assess the effects of cytokinins 6-Benzyladenine (BA) and Forchlorfenuron (CPPU) acting as plant growth regulators (PGRs). Number of flowers per inflorescence, female-to-male ratio of flowers, fruits per infructescence, fruiting rate, number of seeds per fruit, seed size and weight as well as seed oil content were determined. It was suggested that concerning effectiveness of exogenous application of PGRs the developmental stage of flower is very important. Due to that, special interest was laid on the age of inflorescences at the time of application. Our experiments revealed a strong dependence of cytokinin effectiveness on the developmental stage of flowering. So treatment of plants with 6-Benzyladenine at the beginning of flower formation (stage 1) significantly increased the number of male and female flowers per inflorescence, whereas treatment at an advanced flowering stage (stage 2) or at the stage of fully developed flowers (stage 3) had only slight or no effects. In contrast, fruit retention was progressively increased by treatment in stage 2 and 3. Application of Forchlorfenuron significantly increased female-to-male ratio in stage 1 flowers but showed no effects on stage 2 and 3. 6-Benzyladenine as well as Forchlorfenuron showed equal effects on number of fruit inflorescences treated in stage 1. Our results show a significant decrease in seed weight due to BA- and CPPU-application while kernel weight remained stable. Concerning fruits, clusters and oil yield per tree, BA-application showed significant increasing effects. This study indicates that 6-Benzyladenine and Forchlorfenuron can improve yield affecting parameters in J. curcas when the phenological stage of flowering at time of application is precisely considered.     

Floral display size in comfrey, Symphytum officinale L. (Boraginaceae): relationships with visitation by three bumblebee species and subsequent seed set

The fecundity of insect-pollinated plants may not be linearly related to the number of flowers produced, since floral display will influence pollinator foraging patterns. We may expect more visits to plants with more flowers, but do these large plants receive more or fewer visits per flower than small plants? Do all pollinator species respond in the same way? We would also expect foragers to move less between plants when the number of flowers per plant are large, which may reduce cross-pollination compared to plants with few flowers. We examine the relationships between numbers of inflorescence per plant, bumblebee foraging behaviour and seed set in comfrey, Symphytum officinale, a self-incompatible perennial herb. Bumblebee species differed in their response to the size of floral display. More individuals of Bombus pratorum and the nectar-robbing B.?terrestris were attracted to plants with larger floral displays, but B. pascuorum exhibited no increase in recruitment according to display size. Once attracted, all bee species visited more inflorescences per plant on plants with more inflorescences. Overall the visitation rate per inflorescence and seed set per flower was independent of the number of inflorescences per plant. Variation in seed set was not explained by the numbers of bumblebees attracted or by the number of inflorescences they visited for any bee species. However, the mean seed set per flower (1.18) was far below the maximum possible (4 per flower). We suggest that in this system seed set is not limited by pollination but by other factors, possibly nutritional resources.     

Effects of some natural and synthetic growth regulators on sex-expression of Myrica esculenta Buch-Ham. ex D. Don

Gibberellic acid (GA,), chlorflurenol and ethrel were applied at different concentrations to either male or female trees of Myrica esculenta. GA₃ induced intersexual flowers both on the male and female trees whereas chlorflurenol and ethrel induced similar (intersexual) flowers but only on the male plants. When GA₃ was applied in combination with chlorflurenol, fewer intersexual inflorescences appeared on the male plants along with a significant decline in the number of flowers per inflorescence. In combination, chlorflurenol and ethrel induced copious female and intersexual inflorescences per male plant, especially when two successive treatments of 100 mg/I of chlorflurenol and 1920 mg/l of ethrel were applied. The induced female inflorescences later bore fruits.     

Gender variation of sequential inflorescences in a monoecious plant Sagittaria trifolia (Alismataceae)

In protogynous plants, female flowers of early blooming plants are at a reproductive disadvantage because they cannot set fruit due to the lack of available pollen. To study this phenomenon, gender expression of the monoecious herb Sagittaria trifolia was investigated over the entire flowering season in two field and two cultivated populations in Hubei and Hunan Provinces, China. In racemes of S. trifolia, flowers open sequentially from bottom to top, with female flowers opening first followed by male flowers. This creates a temporal separation of sexes in the species. Under field conditions small plants are often male, with production of both male and female flowers increasing with plant size. Femaleness increased among sequential inflorescences since female flower production increased whereas male flower production did not. Seed production was greater in large inflorescences because they contain more female flowers, and the number of ovules increased in female flowers at basal positions within the raceme. A consistent pattern of high seed set was observed in flowers from both field and cultivated populations. About 1 % of unfertilized ovules resulted from no pollination and 2 % of the seeds produced were only partly developed due to resource limitation. In the first inflorescence of the six experimental populations, 6.7-40.0 % of individuals produced only male flowers, and female flowers of 1.9-6.5 % individuals were aborted. The occurrence of male flowers in early blooming inflorescences could be an adaptive strategy to conserve resources and enhance pollination of female flowers in protogynous S. trifolia.     

Observations of inflorescence patterns and flower sex in a population of Sagittaria papillosa Buch. (Alismataceae)

Sagittaria papillosa Buch. is monoecious with unisexual flowers, pistillate below, staminate above, typically with an unbranched scape. A large population with unusual numbers of staminate and bisexual flowers on the lowest whorl of the inflorescence and many particles was quantitatively evaluated. First-formed inflorescences had more staminate and bisexual flowers than those produced later. Branched scapes were predominantly found to be the second inflorescence produced by a given plant. Genetic crosses between flowers on recemes and panicles produced no branched inflorescences. When grown under greenhouse conditions all tested plants had racemes with pistillate flowers in the lower whorls and staminate ones above. Data from soil parameters, daylengths and air temperatures are compared to reported information on modification of flower sexuality by these factors.     

Time of application of Niagara 10637 for induction of maleness or femaleness inRicinus communis Linn.

Ethyl hydrogen-1-propylphosphonate (Niagara 10637) at concentrations of 500, 1000 and 2000 mg/l had two different effects on sex expression ofRicinus communis L. cvIari 132. Higher concentrations (1000 and 2000 mg/l), applied just before emergence of inflorescence i.e. to 90 day old plants, induced a marked increase in female flower number and reduced the number of male flowers on the first inflorescence. However, there was a tendency towards maleness on the second and third inflorescences. When applied to 60 day old plants, the test compound induced a high degree of maleness on the first and second inflorescences. Sex expression was not markedly altered with treatments at still younger stages (seeds and seedlings).