敦煌‘李光杏’花芽发育过程中雌蕊败育观察及生物学特性调查

为克服杏生产中雌蕊败育现象、提高坐果率,该研究以甘肃省敦煌市的‘李光杏’盛果期不同树势(强势树、中庸树和弱势树)和不同类型结果枝(花束状果枝、短果枝、中果枝、长果枝)的花芽为试材,对其开花物候期及生物学特性进行调查,采用石蜡切片观察易发生败育时期(花芽分化初期、雌蕊分化期、花粉细胞期和花蕾膨大期)的花芽内部组织结构形态,同时测定各主要败育时期叶片可溶性糖、淀粉含量及矿质元素的变化。结果表明:(1)弱树花芽的平均败育率最高(91.26%),中庸树最低(71.08%);不同类型结果枝中,花束状果枝花芽的败育率最低,长果枝的败育率最高。(2)不同结果枝类型的花粉生活力表现为花束状果枝>短果枝>中果枝>长果枝,花粉发芽率表现为短果枝>花束状果枝>中果枝>长果枝。各花型花粉生活力表现为雌蕊高于雄蕊>雌雄等长>雌蕊低于雄蕊>无雌蕊,发芽率的表现为雌雄等长>雌蕊高于雄蕊>雌蕊低于雄蕊>无雌蕊。(3)各树势花芽雌蕊分化期叶片可溶性糖与淀粉含量显著低于其他时期;叶片P、K、Ca含量在分化前期较高,但是雌蕊、雄蕊分化期显著下降。(4)与正常花相比,败育花主要表现为子房发育异常,多数生长点不均匀,子房萎缩,胚珠原基发育停滞;雌蕊的花柱低于花丝,且花粉粒急剧减少。研究发现,‘李光杏’树势的强弱会造成败育花比例和坐果率的差异,并以中庸树果实坐果率最高,且花败育率最低;雌蕊发育是否正常直接关系到‘李光杏’正常开花,雌蕊的发育受阻,最终成为整个花芽退化的主要形式;叶片碳水化合物和矿质元素等营养物质参与并保证了花器官的正常发育。     

中国主要苜蓿品种的产量性状及其多样性研究

对28个4龄苜蓿品种单株产量性状及其相关性和变异进行了研究．结果表明,品种间单株干物质产量及各产量性状存在显著差异,其中单株干物质产量最高和较高的分别是新疆大叶(452．8g·株^-1)和甘农3号(373．0g·株^-1);叶片最宽和最长者均为新疆大叶和甘农3号;单株枝条数增加最多是第3茬,3茬单株枝条数最高和较高的品种是新牧1号、图牧2号、肇东和北疆;苜蓿株高生长高峰期在第1茬,生长最快的品种为甘农3号和新疆大叶．相关分析表明,单株干物质产量与株高及枝条数等构成因素之间存在显著或极显著相关,其中1、3茬株高及3茬单株枝条数等性状相关最好,呈显著相关的品种达19～22个,且相关系数亦最高．产量性状变异分析表明,品种内变异大于品种间变异,前者占总变异的76．0％～93．8％,而后者仅占6．1％～24．0％．各性状变异程度表现依次为3茬单株枝条数>单株干物质产量>1茬单株枝条数>2茬单株枝条数>春季株高>3茬株高>2茬株高>叶宽>现蕾期株高>叶长>1茬株高．     

花生主要性状遗传力和相关性的研究

1.材料为1960～1961年杂交的三个组合。选用的亲本,为生产应用的两个主要类型(普通型、珍珠豆型)。这两个类型的品种,在生态和生物学特性上都有比较明显的区别。采用这两个类型进行品种间有性杂交,选出的优良品种也较多。 2.花生性状遗传力的大小,在不同的估算方法(广义法及上下代亲子相关法)间,除总分枝、总果枝出入较大外,其他几个性状都有大体一致的趋势。百果重、饱果数、单株结果数、生育日数、主茎高等性状遗传力较高,秕果数、单株产量等性状的遗传力较低。 3.单株产量,从世代间(F_(2-3))的遗传力来看是很弱的,因此,对于单株产量的选拔标准不宜控制过严,特别是双亲生态型相差悬殊的组合,更有必要放宽选拔的标准。此性状于第二代通过直接选择是无效的,但与单株产量有密切关系的却有几个性状,如单株结果数、饱果数等。因此,通过间接性状的选择,亦可能选择出单株生产力高的优良品系。 4.产量与其他性状的相关性表明,单株结果数越多,产量越高,饱果数越多,产量越高,说明果多果饱是决定产量高低的主要因素。 5.利用变异系数的平方代替相应的变量来估算广义遗传力,可以起到一定的矫正作用。     

甘蓝型油菜数量性状遗传变异的研究

本试验采用单因素遗传设计,连续两年分别研究了42个和50个稳定遗传的甘蓝型油菜品种22个数量性状的平均表现和遗传变异,结果表明,开花期、株高、分枝高度、着粒密度、每果粒数、千粒重、一次分枝数、总角果数、单株产量和含油量的表现受大环境的影响较大。开花期、果长、千粒重、主花序长度的遗传力高,总角果数、单株产量、着果密度、分枝高度、每果粒数的遗传力较低。随着芥酸含量的降低,开花期延迟,主花序变短,主花序角果数减少。无芥酸品种的总角果数和单株产量显著低于有芥酸品种。中国的高芥酸品种具芥酸含量显著高于国外的高芥酸品种。     

绿豆5个产量相关性状的QTL分析

利用绿豆(Vigna radiata)品种苏绿16-10和潍绿11杂交构建的F2和F3群体发掘调控绿豆产量相关性状的遗传位点。同时对绿豆产量相关性状进行表型鉴定和相关性分析,并利用构建的遗传连锁图谱进行QTL定位。结果表明,单株产量与单株荚数、单荚粒数、百粒重和分枝数均呈正相关。单株产量与单株荚数的相关性最高,这2个性状在F2和F3群体中的相关系数分别为0.950和0.914。在F2群体中,共检测到8个与产量性状相关的QTL位点,其中与单株荚数、单荚粒数和单株产量相关的QTL位点各1个,分别解释11.09%(qNPP3)、17.93%(qNSP3)和14.18%(qYP3)的表型变异;2个与分枝数相关的QTL位点qBMS3和qBMS11,分别解释18.51%和7.06%的表型变异;3个与百粒重相关的QTL位点qHSW3、qHSW7和qHSW10,分别解释5.33%、46.07%和4.24%的表型变异。在F3群体中,qNSP3和qHSW7再次被检测到,表明这2个QTLs有较好的遗传稳定性。同时,开发了1个与百粒重主效QTLqHSW7紧密连锁的InDel标记R7-13.4,并利用自然群体对...     

国槐DNA导入花生D5代性状遗传变异的分析

利用花粉管通道技术对国槐DNA导入花生栽培品种79266,D2代变异株98D010－7经连续自交,D3代获得9个株系,61个株行,641个单株,观察D5代群体内每个单株的开花型、株型、主茎高、第一对侧枝长、分枝数及单株结果数等主要农艺性状的表现型。结果表明：（1）79266和98D010－7均为连续开花型,D5代出现了交替开花型变异株,占总株数4．37％,开花型分离株行占16．39％;（2）79266株型直立,98D010－7株型葡匐,D5代表现型有直立,葡匐和半葡匐3种类型,分别占34．95％、14．04％和51．09％;表现分离的株行占73．77％;（3）株高和第一对侧枝长与79266相比显著降低;（4）单档分枝数与受体平均值相近,只有1个株系分枝数显著少于受体79266,其它8个株系差异不显著;（5）D5代群体有3个株系的单株结果数显著大于受体79266的单株结果数。     

播种季节和种植方式对多年生苦荞主要农艺性状的影响

该研究选取六个多年生苦荞新品系,对春季、秋季直播与秋季再生其主要农艺性状进行调查。结果表明:(1)不同播种季节对多年生苦荞新品系主花序的花粉可育率、总结实率、有效结实率、植株株高、主茎粗、主茎分枝数、主茎节数、籽粒百粒重、单株粒数、单株产量的影响均达到显著或极显著水平;秋播主花序花粉可育率、总结实率、有效结实率、植株主茎分枝数、籽粒百粒重、单株粒数、单株产量均极显著高于春播;植株株高、主茎粗、主茎节数均极显著低于春播;主花序花朵大小、籽粒种子长宽比无显著差异。(2)不同种植方式对主花序花粉可育率、有效结实率、植株主茎节数及籽粒百粒重的影响达到显著或极显著水平;秋季再生主花序花粉可育率、籽粒单株粒数显著高于秋季直播;主花序有效结实率、植株主茎粗、主茎节数、籽粒百粒重显著低于秋季直播;主花序花朵大小、总结实率、植株株高、主茎分枝数、籽粒种子长宽比、单株产量无显著差异;相关分析表明,各生长季节下主花序有效结实率及单株粒数与单株产量的相关系数均最高。(3)所有参试品系中,1612-241秋季直播的单株产量显著高于其他品系; 1612-16、1612-33秋季再生单株产量较正季优势显著。该研究结果有助于筛选出适宜一季播种两季收获的优良品系,为今后多年生苦荞的选择育种提供线索基础。     

种植方式与密度对油后棉生育特性及产量构成的影响

为提高棉油两熟作物的产量,实现棉花不同种植方式与密度的合理结合,2013年在湖南省4个试验点研究了密度与种植方式对棉花生育特性及产量构成的影响。结果表明,种植方式和密度对棉花产量的互作效应不显著,各种植方式间以营养钵的产量最高,直播产量最低,但无显著性差异。在同一种植方式中,果枝数、单株成铃数随密度增高而降低,产量随密度的增加而增加。在同一密度下,生育期以直播最短,单株成铃数以营养钵最高、果枝层数以漂浮最多、株高、果枝始节位以直播最高,不同处理对棉花铃重、衣分、衣指、子指影响不显著。直播高密度的产量与营养钵中密度、漂浮高密度产量相当。结果表明,不同种植方式之间产量无显著性差异,直播、营养钵、漂浮三种种植方式均适用于湖南油后棉种植,直播的日产量最高,漂浮日产量最低,适当加大直播种植密度,有利于提高棉花产量,为推广棉花轻简化栽培提供理论依据。     

不同株型芝麻种质湿害后产量性状研究及耐湿性评价

于盛花期对66份种质进行湿害处理,结果表明:湿害对单秆型和分枝型种质的产量性状影响差异明显,对单秆型芝麻产量性状的影响(湿害指数值)大小依次为单株种子干重(69.18%)蒴果数(67.48%)有效果节数(49.10%)有效果轴长度(45.69%)株高(16.40%),对分枝性芝麻的影响依次为分枝有效果节数(65.96%)分枝蒴果数(64.73%)总蒴果数(52.01%)单株种子干重(49.92%)主茎蒴果数(41.66%)主茎有效果轴长度(37.57%)有效分枝数(34.21%)主茎有效果节数(20.12%)株高(15.43%);湿害对三蒴型芝麻的侧位蒴果影响较大,对单秆三蒴型芝麻的影响为侧位蒴果数(92.25%)中位蒴果数(50.25%),对分枝三蒴型芝麻的影响为分枝侧位蒴果数(92.86%)主茎侧位蒴果数(69.14%)分枝中位蒴果数(44.17%)主茎中位蒴果数(32.97%)。根据相对湿害产量可以将供试种质聚为耐湿与不耐湿二大类,不耐湿类型种质61份,占92.42%;耐湿类型种质5份,占7.58%,为竹山白芝麻、西平二郎花、阜南芝麻、嘉兴紧口黑和麻城黑芝麻,可作为耐湿种质加以利用。     

濒危植物矮沙冬青开花物候研究

对矮沙冬青(Ammopiptanthus nanus Cheng f.)的形态学特征、开花物候及花空间分布进行了研究,结果表明:在单花、花序、单株、居群水平上的开花物候都表现出很强的开花不同步性,在单花、单花序水平主要表现在单花寿命4~9 d不等,平均(6.74±1.23)d,以7 d出现的频率最高;单花序开花持续时间范围在4~13 d,平均(8.33±2.63)d,以10 d出现的频率最高;单株及居群水平上表现更为明显.矮沙冬青的花具有虫媒传粉的特征,花主要分布在花枝的上部,下部花所占比例很小,有很多花枝花全部为上部花.相关性分析表明上部花和总花数相关性极显著(r=0.990,P<0.01),而中部花、下部花和总花数的相关性不显著,甚至呈负相关.单株不同方位开花数量差异不显著(F=0.0579,P>0.05).     

疏花对富士苹果光合同化物分配的外部调节和生理表现

在盛花期,利用对树冠不同部位疏除花序的试验。对富士苹果树体内同化物的调配及其生理表现进行了研究。结果表明,苹果平均单果重和平均单果叶面积之间关系呈线性正相关。该相关关系在不同处理之间无差异（r=0.91),充分说明在苹果树体内存在一个可自由流动的碳水化合物库或者说树体对结果具有光合调节作用,疏花可以从外部调节光合同化物分配的方向。对每株苹果树未结果部位和结果部位短枝及延长枝叶片净光合速率测定表明。结果和未结果部位光合速率没有显著差异。虽然疏花没有显著影响苹果单株枝条生长量和叶面积,但是,苹果树树冠全部疏除花序的一侧 或主枝的平均枝条生长量和叶面积去比该树其它结果部位分别平均高出153.5cm和8900cm^2,差异极为显著。苹果树疏除花序1/2或3/4的数量使苹果平均单果重比不疏花分别显著增加了33g或79g。而果实钙浓度每百克鲜重分别降低了1.62mg或2.66mg,充分说明当疏花显著地影响果实大小时,果实内钙浓度也会明显地发生相应的变化,虽然在疏花处理之间不同部位疏除花序没有影响单株花芽总数量,但是,每株树前一年春季疏花的部位比未疏花,结果的部位极显著地增加了花芽数量（SED=11.6)。     

辣椒杂种一代生化特性与农艺性状的灰色关联分析

用灰色关联分析方法研究了辣椒雄性不育杂种一代农艺性状与单株产量间、花蕾、叶片中生化物质含量与农艺性状间关系的密切程度。结果表明,农艺性状与单株产量问关联度的大小顺序依次为株幅、株高、果长、结果数、单果质量、第一花节位、果宽和侧枝数,花蕾中生化物质含量与农艺性状问总体关联度的大小顺序依次为可溶性糖、可溶性蛋白质、过氧化物酶活性、脱落酸、生长素、游离脯氨酸和玉米素,叶片中生化物质含量与农艺性状问总体关联度的大小顺序依次为可溶性糖、过氧化物酶活性、游离脯氨酸、脱落酸、生长素、玉米素和可溶性蛋白质。     

THE EMERGENCE AND DEVELOPMENT OF BRANCHES IN CROTALARIA JUNCEA AND THEIR RELATIONSHIP TO FLOWERING

Nanda , K. K. (Forest Res. Inst., Dehra Dun, India.) The emergence and development of branches in Crotalaria juncea and their relationship to flowering. Amer. Jour. Bot. 49(4): 334–341. Illus. 1962.—Seeds of Crotalaria juncea L. were sown in pots on March 23, 1959, and records were kept of the dates of emergence of individual branches and the appearance of flower buds on them. Periodical observations were also made of the height of the main shoot as well as its branches and the number of nodes and leaves borne by them throughout the year. The main shoot elongates rapidly and terminates in an inflorescence. Development of lateral buds remains completely arrested during the period of rapid elongation and is initiated only after the appearance of the floral buds when it takes place in basipetal sequence. The flowering of the branches also takes place in a basipetal manner. This mode of emergence of branches and their flowering are exhibited even by secondary and tertiary branches. The length attained by these branches is very small as the flower buds appear soon after their emergence. In contrast, the branches formed towards the middle of May continue to elongate for a considerable period and become many times longer than the main shoot or the branches produced earlier in the season. The vegetative period of these branches is also very much prolonged. These differences in the height attained by branches produced at different times of the year and the basipetal sequence in the emergence of branches and their flowering appear to be under the control of some physio-chemical changes which cause the transformation of the growing apex from the vegetative to the reproductive state. This holds good irrespective of whether these changes are brought about as a result of a favorable environmental complex, as is the case with the main shoot and late-formed, much elongated branches, or are due to the favorable internal conditions produced within the plant as a result of the completion of the developmental process of the main shoot, as happens in the case of branches produced earlier in the season.     

COMPARATIVE EFFECTS OF GIBBERELLIN AND INDOLE COMPOUNDS ON THE INDUCTION OF PARTHENOCARPY IN SEXUALLY INCOMPATIBLE PERESKIA ACULEATA

Sachar , R. C. (U. Delhi, India.) Comparative effects of gibberellin and indole compounds on the induction of parthenocarpy in sexually incompatible Pereskia aculeata. Amer. Jour. Bot. 49(9): 913–917. Illus. 1962.—The effects of indoleacetic acid (IAA), indolebutyric acid (IBA), gibberellin (G) and gibberellic acid (GA) were studied on the fruit growth of the sexually incompatible Pereskia. Under natural conditions, this plant did not produce any fruits and seeds, and the flowers abscised a week after anthesis. IAA (50–500 ppm) delayed the formation of an abscission layer by another 2 weeks, but it was ineffective in inducing parthenocarpy. IBA (50–500 ppm) induced fruit-set in only 15% of the flowers. Best response was achieved by G (100–500 ppm), or GA (100–500 ppm), which gave 100% fruit-set. The effect of GA in inducing parthenocarpy was not inhibited when used in conjunction with IAA. Maximum size of the fruits was obtained with 2 sprayings of GA, and subsequent sprays were of no consequence. Further, fruit size was the largest when GA or G was sprayed at anthesis, or on old flower buds, but it was much less when the chemicals were sprayed on young flower buds. There was no stimulation of the growth of ovules; instead, a translucent mucilaginous placental tissue developed within the cavity of the fruit wall. Attempts were made to culture ovules and the placental tissue on artificial nutrient medium, but without success.     

A REEXAMINATION OF THE POLLEN-DONATION HYPOTHESIS IN AN EXPERIMENTAL POPULATION OF ASCLEPIAS EXALTATA

The evolution of large floral displays in hermaphroditic flowering plants has been attributed to natural selection acting to enhance male, rather than female, reproductive success. Proponents of the “pollen-donation hypothesis” have assumed that maternal resources, rather than levels of effective pollination, limit fruit set. We investigated the pollen-donation hypothesis in an experimental population of poke milkweed, Asclepias exaltata, where effective pollination did not limit fruit set. Specifically, we examined the effects of flower number per plant, and flower number per umbel on male reproductive success (number of fruits sired) and female reproductive success (number of fruits matured). In 1990, a paternity analysis was performed on fruits collected from 53 plants whose inflorescences were not manipulated. Flower number per plant was significantly correlated with male success, but not with plant gender. Flower number per plant was also significantly correlated with female success, but umbel number and stem number per plant together explained more than half (58%) the variation in female success. The percentage of fruit set was not significantly correlated with flower number per plant. Plants with large floral displays did not disproportionately increase in male reproductive success, relative to female success, as predicted by the pollen-donation hypothesis. In 1991, the effect of flower number per umbel on male and female reproductive success was investigated. Flower number per umbel was manipulated on four umbels per plant by removing flowers to leave 6, 12, or 18 flowers in each umbel. Plants with the largest umbels effectively pollinated twice as many flowers on other plants, but produced only 1.35 times as many fruits as plants with 6 and 12 flowers per umbel. Relative maleness of plants with large umbels was nearly twice that of small and medium umbels. Although these observations are consistent with the pollen-donation hypothesis at the level of umbels, they are problematic, because much of the variation in flower number per umbel exists within, rather than among, plants in natural populations. Thus, plants consist of both reproductively male (large) and female (small) inflorescences, which act to increase total reproductive success. It is therefore inappropriate to explain the evolution of large floral displays in milkweeds solely in terms of potential male reproductive success.     

How plant allometry influences bud phenology and fruit yield in two Vaccinium species

Background and AimsUnderstanding how plant allometry, plant architecture and phenology contribute to fruit production can identify those plant traits that maximize fruit yield. In this study, we compared these variables and fruit yield for two shrub species, Vaccinium angustifolium and Vaccinium myrtilloides, to test the hypothesis that phenology is linked to the plants’ allometric traits, which are predictors of fruit production.MethodsWe measured leaf and flower phenology and the above-ground biomass of both Vaccinium species in a commercial wild lowbush blueberry field (Quebec, Canada) over a 2-year crop cycle; 1 year of pruning followed by 1 year of harvest. Leaf and flower phenology were measured, and the allometric traits of shoots and buds were monitored over the crop cycle. We hand-collected the fruits of each plant to determine fruit attributes and biomass.Key ResultsDuring the harvesting year, the leafing and flowering of V. angustifolium occurred earlier than that of V. myrtilloides. This difference was related to the allometric characteristics of the buds due to differences in carbon partitioning by the plants during the pruning year. Through structural equation modelling, we identified that the earlier leafing in V. angustifolium was related to a lower leaf bud number, while earlier flowering was linked to a lower number of flowers per bud. Despite differences in reproductive allometric traits, vegetative biomass still determined reproductive biomass in a log–log scale model.ConclusionsGrowing buds are competing sinks for non-structural carbohydrates. Their differences in both number and characteristics (e.g. number of flowers per bud) influence levels of fruit production and explain some of the phenological differences observed between the two Vaccinium species. For similar above-ground biomass, both Vaccinium species had similar reproductive outputs in terms of fruit biomass, despite differences in reproductive traits such as fruit size and number.     

EFFECT OF DEFOLIATION ON GENDER EXPRESSION AND FRUIT SET IN PASSIFLORA INCARNATA

We examined the effect of defoliation on gender expression and fruit set in a north-central Florida population of the andromonoecious vine, Passiflora incarnata, during the 1984 flowering season. At three times during the flowering season (May, June, July), the leaves adjacent to flowers at four stages of development were removed, and subsequent sex and fate of each flower were determined. Defoliation affected gender of the flower by significantly decreasing the probability that the styles of the flower would deflex and the flower would thus function only as a pollen donor. Flowers were sensitive to defoliation at any stage before anthesis, though the sensitivity appeared to decrease in the most mature category of flower buds. Fruit set of hermaphroditic flowers remained unaffected by defoliation, but the probability of fruit set and gender expression were significantly influenced by the time of the flowering season. We conclude that the local photosynthate environment determines flower gender in Passiflora, but branch or entire plant photosynthate resources can compensate for local resource fluctuations and play an important role in fruit set and flower bud abortion. The sexual lability of Passiflora incarnata appears to be an adaptation to uncertain resource levels at a fine scale, caused by nearby developing fruits and the possibility of herbivore defoliation.     

Between-year variation in flowering and fruit set in frost-prone and frost-sheltered populations of dioecious Rubus chamaemorus

Summary The flowering and fruiting patterns of the dioecious perennial herb Rubus chamaemorus L. were studied in frost-prone (open) and frost-sheltered (Shaded) habitats in northern Sweden over 6 years. The number of ramets with flower buds, the proportion of flower buds that opened, and fruit set varied markedly between years. In the frost-prone populations, the occurrence or absence of detrimental frosts during the development of flowers and fruit could explain much of the variation, both in the proportion of flower buds that developed into flowers, and in fruit set. In the frost-sheltered populations, most female flowers that did not develop into fruit aborted without any signs of physical damage and before any ovules had begun to enlarge. Flower mortality caused by herbivores feeding on reproductive parts was commonly low, but reached values higher than 10% in one of the shaded populations. Hand-pollination increased the proportion of ovules producing seeds in the mature fruits by about 20%, and in one year also increased fruit set significantly in one population. Fruit-producing female ramets had a higher mortality and a lower probability of flowering in the subsequent year than male ramets and non-fruiting female ramets. In R. chamaemorus, the conditions for fruit maturation are highly unpredictable at the time of flower initiation. It is suggested that the apparent over-initiation of flower buds is advantageous, as it allows the plant to attain a high reproductive success in years favourable for flowering and fruit development.     

Sexual dimorphism and fruit production in a dioecious understory tree,Ilex opaca Ait.

Summary This study suggested that sexual selection is potentially an important factor in the maintenance of dioecy in the American holly, Ilex opaca (Aquifoliaceae). Sexual dimorphisms in flower production and phenology were highly significant in this understory tree. On average, individual males produced 7.4 times as many flowers as did female trees. Staminate flowers lasted only a single day, whereas pistillate flowers lasted 3–4 days, during which they showed no significant decline in their ability to produce fruit after pollination. Individual male trees opened their flower buds asynchronously during the season, maximizing the number of days they were in flower. Individual females opened their buds more synchronously, maximizing their floral display at one point in time. Females produced fruits in numbers that were somewhat less than proportional to their flower production. Fruit development was initiated from only 38.9% and 69.5% of pistillate flowers in 1987 and 1988, respectively. By the time of ripening, an average female had lost 62.3%, 24.3%, and 11.1% of its initial fruit crop in 1986, 1987, and 1988, respectively. The proportion of fruit lost in 1986 was independent of the number of fruit that initially began development. In 1988, artifically supplementing pollen to a large number of flowers failed to increase either fruit or seed production relative to control branches with unsupplemented flowers. This suggested that resource levels were likely more important than pollen availability in limiting female reproductive success. These observations on I. opaca were consistent with the expectations for a population in which male reproductive success continues to benefit from continued pollinator service and female reproductive success does not.     

Predispersal mortality and fecundity in the grey mangrove (Avicennia marina) in southeastern Australia

Abstract The predispersal mortality of floral buds and fruits in the grey mangrove (Avicennia marina) was examined over a range of populations for 3 years. The average survival of floral buds to anthesis was 34%. Moth larvae (subtribe Phycitina) attack and consume the contents of variable numbers of flower buds, but their activities did not influence bud survival, as experimental exclusion of larvae did not increase the number of buds surviving to anthesis. Fruit mortality is initially high with an average of 21% of floral buds surviving to immature fruit. Subsequent mortality is lower until on average 2.9% of floral buds survive to become viable propagules. Several cohorts of the phycitine moth larvae feed throughout the development of the fruit, and up to 62% of mature fruit show signs of larval attack. Experimental exclusion of moth larvae doubled the survival of fruits. However more than 75% of fruit mortality may be attributed to maternal regulation. Hail storms can also cause fruit mortality. The potential fecundity (number of ovules) of A. marina was measured over a range of age-size classes of trees and the realized fecundity (viable propagules) was estimated from average predispersal mortality. These estimates were subsequently verified in the field. A fecundity schedule was constructed with assumptions on reproductive frequency and reproductive life. The average annual supply of propagules over a lifetime is estimated to be about 247 viable propagules per tree.