Pollination requirements of eight cultivars of black currant (Ribes nigrum L.)

Summary

Fruit set and yield of the following cultivars of black currant (Ribes nigrum L.): `Ben Alder', `Ben Lomond', `Ben Nevis', `Ben Tirran', `Ceres', `Ojebyn', `Titania' and `Triton' were investigated in 1994±1996. Percentage fruit set, size of berries and yield of all investigated cultivars were higher when much foraging activity of pollinating insects was observed. The bushes on open-pollinated plots set more fruit (50-200%), had bigger fruits (10±20%) and gave higher yields (60±300%) than plants isolated from insects. All eight cultivars, including `Titania', had lower fruit set when pollinated with their own pollen under nets than when subjected to free pollination in open plots.     

A Study of the Plant/Insect Relationships and Pod-Setting in the Runner Bean (Phaseolus Multiflorus)

Pod-setting in runner bean crops depends on the building up and maintenance of a sufficiently large population of efficient insect pollinators, and this appears to be affected by the early spring weather.

Runner bean flowers were visited and could be pollinated both by bumblebees (Bombus spp.) and honeybees (Apis mellifera). Visits to the front of the flower for nectar or pollen resulted in pollination, but “nectar-robbing” via a hole bitten through the underside of the flower, caused little or no pollination. During periods of intense nectar-robbing activity, pollination efficiency varied widely and depended largely upon whether or not insects were also collecting pollen from the crop.

A technique was devised for measuring the daily insect pollinating efficiency in a crop, that is, the actual daily pod-set as a percentage of the potential daily pod- set. A simple visual method for assessing the current day’s pollinating activity in the field is described, and the efficiency thus indicated compares well with results obtained from experimental pollination efficiency measurements.     

牛角瓜花部综合特征与繁育系统

野外调查发现,牛角瓜（Calotropis gigantean）的自然坐果率较低,影响了利用其种子纤维的开发前景。研究了牛角瓜的传粉生物学,观察了云南元江牛角瓜居群的开花进程、花部特征和访花昆虫,检测了其花粉活力与柱头可授性,并对其进行了人工授粉辅助试验。结果表明：（1）牛角瓜花为聚伞形花序,花冠蓝紫色,花期全年,单花花期7 ~ 8 d,在开花整个过程中花粉一直保持较强活力且柱头具有可授性,花药一直低于柱头,由蜡质薄膜包裹的花粉粒形成花粉块,无法散落至柱头,花药和柱头间存在空间隔离。（2）牛角瓜的杂交指数为4,说明其繁育系统以异交为主,部分自交亲和,需要传粉者。（3）人工授粉试验显示,牛角瓜不能在柱头表面完成授粉,而是在柱头腔中,且存在一定的传粉限制;没有自发的自花传粉现象,在自然条件下也没有无融合生殖现象,人工异株授粉结实率比自花授粉结实率高。（4）昆虫借助足部特殊结构将花粉块移出并将花粉块通过花药裂口插入柱头腔中以完成授粉;牛角瓜访花昆虫共有10余种,传粉昆虫主要有膜翅目的黑小蜜蜂、圆柄木蜂和木蜂。花粉限制是牛角瓜坐果率低的主要原因,可通过放养传粉昆虫来提高牛角瓜的坐果率,从而增加其种毛纤维的产量。     

Flower emasculation accelerates ovule degeneration and reduces fruit set in sweet cherry

Flower emasculation is commonly used to make flowers unattractive to pollinating insects and to carry out controlled pollinations. In sweet cherry, we have observed recurrent low fruit set after flower emasculation and compatible pollination without apparent causes. This led us to evaluate its effect on the progress of the reproductive phase and on fruit set in this species. Flower emasculation reduced by more than a half the fruit set obtained in crosses made during two consecutive years. This effect could be traced back to the first week after anthesis where weight increase of pistils from emasculated flowers was smaller and ovule degeneration was accelerated compared to pistils from non-emasculated flowers. Pollen tubes, which behaved similarly at the stigma-style level in emasculated and non-emasculated flowers, lost their directionality in the area close to the degenerated ovule in the ovary. While flower emasculation is valid to evaluate pollen tube performance in the style and to determine incompatibility relationships, the lower fruit set registered after emasculation alerts on its use in fruit set experiments and breeding programs.     

The pattern and control of reproductive development in lychee: A review

Often there is no relationship between yield and flower production in lychee (Litchi chinensis Sonn,). This is because of the high rate of premature flower and, especially, fruit abscission between floral initiation and fruit maturation. There is the possibility that low female-to-male sex ratio, lack of pollinating insects, poor pollen transfer, low pollen viability and failure of pollen tube growth may also reduce fruit set, while poor fruit development may reduce final fruit size.Detailed studies are required on the effects of genotype and environment (temperature, soil moisture, humidity and mineral nutrition) on the growth and abscission of the flowers and fruit. Potential techniques for improving the setting and retention of fruit include varietal selection, withholding of nitrogen fertilization during flowering and early fruit growth (to reduce vegetative flushing), and the maintenance of plant moisture status (irrigation, overhead misting and windbreaks).     

Water spray as a potential thinning agent for date palm flowers (Phoenix dactylifera L.) c.v. ‘Lulu’

Flower or fruit thinning is a critical cultural practice in the date palm production chain that affects fruit development, quality and yield and regulates tree yearly bearing. Development of a save and economic thinning agent for date palm is critically required especially under harsh conditions. During 2004 and 2005 seasons, water spray for 3 min was applied at different times following mechanical pollination on ‘Lulu’ date palm cultivar growing under Al-Ain oasis conditions. The results showed that water spray following pollination generally decreased fruit set percentage to different extent depending of the time of application. In this respect, the most effective treatment was water spray after 4 h following pollination. This treatment significantly decreased fruit set percentage (48%) compared to the control (79%), as the mean of both seasons. However, the other treatments including water spray 1 h before pollination also decreased fruit set percentage but to a lesser extent. Fruit quality characteristics especially fruit and flesh weight, length and diameter were significantly increased by water spray treatments during the 2004 season, in contrast to the 2005 season. Thinning with water significantly decreased both bunch weight and total yield per tree at the Tamr stage especially when applied after 4 h following pollination. To the best of our knowledge, this is a pioneer study investigating the role of water as a potential thinning agent for date palm flowers. The use of water spray as a save and economic thinner needs, however, more research work to justify the time following pollination and duration of application which may vary upon cultivar, method of pollination and district.     

The native pollinators of an apple orchard: variations and significance

Observations on native and domestic insect pollinators were carried out during the blossom period from 1978 to 1980 in a semi-dwarf apple orchard in Ontario. Weather conditions and numbers of blossoms per tree were also recorded. Apis mellifera was the most frequent pollinator for all years. The Anthomyiidae (Diptera) ranked second for 1978 and 1979, but in 1980 the Andrenidae and Halictidae were of greater importance than the Diptera. The efficiency of the pollinators was determined by analysis of the pollen carried on their bodies. Hymenoptera had more pollen on their bodies than the Diptera. Among the Hymenoptera, the Andrenidae and the pollen-gathering Large Andrenidae had the greatest amount of fruit pollen on their bodies. Among the Diptera, the Syrphidae had the greatest amount of fruit pollen. The effectiveness of the pollinators was evaluated by measuring fruit set, seed set and the effective pollination period. There was no significant difference in fruit set between years inspite of adverse weather in 1979. Native insects were important pollinators, particularly in unfavourable weather.     

苹果杂交授粉方法的比较研究

在果园杂交授粉时设计6种处理 (A:去花瓣、不去雄、不授粉、不套袋;B:去花瓣、去雄、不授粉、不套袋;C:不去花瓣、不去雄、不授粉、套袋;D:不去花瓣、去雄、授粉、套袋;E:自然坐果;F:不去花瓣、去雄、授粉、不套袋)应用于陕西省苹果杂交育种的秦冠、富士、嘎拉共3个核心亲本,花后20 d统计坐果率,进行比较分析.以试图简化苹果杂交育种的传统方法去雄、授粉然后套袋,分析花瓣、自体花粉和套袋对授粉坐果的影响,提出简单可行的杂交育种授粉方法.结果表明:无自交结实能力的嘎拉和有较弱自交结实能力的富士做母本,去掉花瓣,无论有无自体花粉,无人工授粉时结实率均为0;有较强自交结实能力的秦冠做母本,自体花粉在无花瓣时可以形成自交结实,结实率为10%;套袋降低杂交授粉的结实率.说明有较强自交结实能力的秦冠做母本时,杂交授粉需要去掉花瓣和雄蕊,不必套袋;无自交结实能力的嘎拉和富士做母本时,杂交授粉时仅去掉花瓣即可,不必去雄和套袋.     

Seed abortion of ‘Tosa-Buntan’ pummelo pollinated with soft-X-irradiated pollens

Cross-pollination was performed with soft-X-irradiated hyuga-natsu pollens (1000 Gy) for ‘Tosa-Buntan’ pummelo (Citrus grandis (L.) Osbeck). This resulted in the transformation of large and complete seeds into small and empty ones (practically seedless). Although fruit set, fruit retention, total soluble solids content (TSS) and titratable acidity of the juice were not affected, decrement in the fruit size was observed. Two weeks after the pollination, endosperm cell division with free nuclei began in both the non-irradiated and irradiated pollen treatment conditions. Seven weeks after pollination, endosperm division with the cell wall occurred in the non-irradiated pollen treatment conditions; however, the endosperm development ceased in most ovules that underwent the irradiated pollen treatment, and the ovules remained in their free nuclear stage. The delayed degeneration of the ovules, following successful fertilization and commencement of endosperm cell division, allow these seedless fruits to be categorized as pseudo-parthenocarpic.     

Fruit set and quality of loquats (Eriobotrya japonica) as effected by pollinations under sub-humid Mediterranean

A field experiment was conducted during 2005 and 2006 growing seasons at Ras Munif (32°22′N, 35°45′E), Ajloun, Jordan, to evaluate different pollination treatments and their effects on fruit set and quality of loquat fruit grown under Mediterranean conditions. Open, supplemental, rain, and covered pollination treatments were imposed on the selected trees. Results showed that under supplemental and open-pollination, extremely higher fruit set was obtained compared with rain and covered treatments. In spite of a heavy crop load, fruits obtained under open and supplemental pollination were also heavier and larger, this could be partly due to a significant increase in seeds and flesh weight. Sugar content was good for both open and supplemental pollination. Wind plays little or no role in loquat pollination process. Loquat flowers attracted very limited number of bee visitors, A. mellifera, Anthophora albigena and Xylocopa violocea of family Apidae and Halictus quadricinctus of family Halictidae were recorded the only loquat flower visitors. They showed a variation in their visiting time but loquat flowers attracted the highest rate and number during the mid of the day.     

熊蜂授粉对大棚蔬菜产量和品质的影响

为了解熊蜂授粉对大棚蔬菜产量和品质的影响,开展自然授粉和熊蜂授粉对比试验。试验结果表明,熊蜂授粉可提高大棚试验农作物坐果率30%以上,单株产量提高17%以上;试验蔬菜维生素C、总糖、可溶性固形物含量均有所提高;熊蜂授粉可显著提高大棚蔬菜株产量和品质,增加大棚农作物种植效益。     

Pollination management for controlled hybridization of white yam

Pollination and fertilization success in white yam, Dioscorea rotundata Poir., depend on knowledge and good management of factors influencing the availability of open male flowers from which good pollen can be collected for effective use in pollinations of genetically compatible female plants under non-xeric conditions. In vitro germination of pollen from numerous genotypes demonstrated varied viability (0.3–85.0%). However, pollen from bisexual flowers on monoecious plants was inferior to pollen from unisexual flowers from dioecious plants. Natural pollination by thrips is inefficient, such that populations with higher ratios of male to female plants set more fruits. To improve fruit set, hand pollinations should be made with pollen from diverse genotypes, early in the flowering period when net water balance is positive. In crossing-blocks, male plants should be closely interpositioned with female plants to reduce pollination distance, thereby improving pollination and fruit set.     

Fruit set and June drop in Cox's Orange Pippin apple as affected by pollination and treatment with a mixture of gibberellins A4 and A7

Single spray applications of 100 ppm of a mixture of the gibberellins A₄ and A₇ (GA_{4 + 7}) were made on fruiting spurs of the apple cultivar Cox's Orange Pippin to investigate the effect on set, June drop and growth of fruits, as well as on shoot development and flower-bud formation on the bourses. Applications were made from 1 to 50 days after full bloom following partial hand-pollination of flowers, i.e. two stigmas per flower pollinated. In another experiment applications were made from 1 to 20 days after full bloom following complete (five stigmas per flower) or partial (two stigmas per flower) hand-pollination, after open pollination, or on emasculated flowers.GA_{4 + 7} only temporarily increased fruit set after open pollination or after effemination of flowers, and then only after application 1 day after full bloom. GA_{4 + 7} did not affect the very high fruit set after complete or partial hand-pollination. Both latter pollination treatments induced an equally high fruit set.GA_{4 + 7} reduced June drop significantly whenever fruits were left after first drop, except after early applications following open pollination. GA_{4 + 7} was effective in June-drop reduction up to 40 days after full bloom, i.e. until the onset of the June drop.Fruit size was not clearly affected by GA_{4 + 7}. The smaller fruits obtained in some cases after GA treatment could be explained by assuming that maturity was reached by fruits that would have abscised without an exogenous GA_{4 + 7} supply. GA_{4 + 7} also increased seed abortion. Fruit length was increased by GA_{4 + 7} only for applications made up to 20 days after full bloom.GA_{4 + 7} stimulated bourse-shoot development to some extent. Flower-bud formation on the bourses was not clearly affected by GA_{4 + 7}, but was markedly influenced by the presence of fruits.That GA_{4 + 7} reduced June drop so much in spite of a slight promotive effect on bourse-shoot growth and a slight abortive action on seeds suggests that these gibberellins may be specific stimuli for apple-fruit growth after actual fruit set is achieved.     

Effect of pollination intensity,frequency and pollen source on fig (Ficus carica L.) productivity and fruit quality

Yield and fruit quality in fig (Ficus carica L.) are highly dependent on cultural practices especially caprification (pollination). However, this technique remains not well controlled in Tunisia. This study was conducted during two successive years, 2009 and 2010, to investigate different pollination conditions, i.e. number of caprifigs and repetitions of caprification on fruiting of two cultivars Bouhouli (San Pedro type) and Zidi (Smyrna type). In addition, the efficiency of four pollen sources was evaluated to identify the most effective pollinator for female cultivar Zidi. The following parameters were recorded: fruit number per shoot, fruit set, productivity, fruit characteristics and vegetative growth.     

不同授粉品种影响苹果梨果型的试验研究

该研究用7个授粉品种对苹果梨进行授粉试验,结果表明,车头梨、大长把梨能较大的影响苹果梨的果型,授粉后果型表现明显较正.     

不同授粉方式和品种对大棚翠冠梨着果及品质的影响

研究大棚栽培环境下不同授粉方式和品种对翠冠梨着果率和果实品质的影响。结果表明,不同授粉方式以人工点授效果最好,着果率达到96%,果形大,果实内饱满种子多;100倍和250倍花粉悬浮液液体授粉的着果率分别为69.2%和50.1%,除250倍花粉悬浮液液体授粉的单果重显著下降外,其他品质指标均无显著差异,也能满足大棚梨生产上的需要。雪花梨是翠冠梨大棚栽培优良的授粉品种,表现为着果率高、果形大、可溶性固形物含量和固酸比高等优点。     

Studies on the Nutrition of Tulips and Narcissi

Summary

We explored the effects of pollination method (hand cross-, hand self-, automatic self-, and open-pollination) and pollen source on fruit set and growth in four red-skinned pitaya (Hylocereus spp.) cultivars [‘Vietnam White’ (‘VNWhite’), ‘Chaozhou 5’, ‘Orejona’, and ‘F11’] in Taiwan.‘VN-White’ has white flesh, while the other three cultivars have red flesh. There were no significant differences in pollen viability or germination rate among the four cultivars, irrespective of whether the pollen was collected at night (approx. 20.30 h) or on the following morning (approx. 08.30 h).The results also indicated that ‘VN White’ was fully self-compatible and exhibited a high fruit set percentage (80 - 96%) following all pollination treatments. This cultivar produced the largest fruit from both hand self- and openpollination, compared to the three other cultivars tested. ‘Chaozhou 5’ was partly self-compatible, and ‘Orejona’ and ‘F11’ were completely self-incompatible. Hand cross-pollination significantly increased the fruit set percentages and mean fruit fresh weights (FWs) in ‘Chaozhou 5’ and ‘Orejona’. Pollen source also significantly affected the fruit set percentage and fruit FW. ‘VN-White’ (after self-pollination) and ‘Chaozou 5’ (after crossing with ‘VN-White’) gave superior fruit set percentages and fruit FWs. Reciprocal crosses between ‘Orejona’ and ‘F11’ also resulted in high fruit set percentages as well as large fruit in both cultivars. Therefore, the source of pollen and the method of pollination can affect fruit production in some cultivars of pitaya. Self-compatibility in ‘VN-White’ concurs with the morphology of its flowers in which the anthers lie in close proximity to the stigma.The distance between the anthers and the stigma may be used an indicator of whether hand pollination is necessary for a pitaya cultivar.     

Spray pollination as a labor-saving pollination system in Japanese pear (Pyrus pyrifolia (Burm.f.) Nakai): Development of the suspension medium

Effects of suspension media used for spray pollination on pollen grain viability were investigated in Japanese pear (Pyrus pyrifolia (Burm.f.) Nakai ‘Kosui’). The suspension media tested in this study consisted of pectin methylesterase (PME) and polygalacturonase (PG) combined with either 0.1% agar or 0.04% xanthangum (XG). We also evaluated the influences of spray pollination on fruit set and fruit quality. Pollen grain viability, as measured by germination and pollen tube growth rates, was maintained in media supplemented with 0.1 mg L⁻¹ PME or 0.1 mg L⁻¹ PG. The level of fruit set after spray pollination using media containing PME or PG in combination with either 0.1% agar or 0.04% XG was almost the same as the level after artificial pollination by hand (hand pollination). The media containing XG combined with either PME or PG seemed to show better results for pollen grain viability and fruit set, although the results were variable from year to year. With regard to fruit size, shape and other parameters for fruit quality, spray pollination and hand pollination gave comparable results, irrespective of the medium composition. The time required for spray pollination was less than half of that required for hand pollination, and the amount of pollen grain required for spray pollination was one-third or less than the amount required for hand pollination. Thus, spray pollination may be a time- and labor-saving pollination system for the cultivation of Japanese pear.     

Pollen load affects fruit set,size, and shape in cherimoya

Cherimoya (Annona cherimola Mill.) is a subtropical fruit crop that exhibits protogyny dichogamy and for which the original pollinators are not present in the main producing countries. Under such circumstances the achievement of profitable yields depends on hand pollination. The present work explores the effects of the amount of pollen applied on pollen–pistil interaction and on fruit set, size, shape and growth. Pollen dilution with Lycopodium spores reduced fruit set and size and favoured the appearance of misshapen fruits, whereas the application of double amount of pollen did not improve fruit size and increased fruit set only the first year. Pollen load did not affect fruit growth model, which always followed a double sigmoid pattern. Nevertheless, the slopes of the curves during the two rapid growth phases were higher when a larger amount of pollen grains was applied. Seed index (seed number per 100 g of fresh fruit weight) rose slightly as pollination level increased.     

Floral biology,pollination ecology and seed production of the ornamental plant Salvia splendens Sello

Summary

In this paper, the floral biology and pollination ecology of Salvia splendens are described. All flower characteristics (red corolla, large tubular flowers with abundant but dilute nectar) indicate that S. splendens is adapted to hummingbird pollination. Honeybees, however, were also found to be good pollinators of this plant. Apis mellifera was equally effective in pollinating S. splendens as hand pollination and open pollination, resulting in a 300% increase in seed set compared with bagged control plants. The much smaller stingless bee Tetragonisca angustula was not an effective pollinator of these flowers since during visitation its body failed to touch the stigma. Although pollination seemed not to be the only limiting factor in seed production, external pollinators enhance seed production in S. splendens, and Apis mellifera is an effective, commercially available pollination agent of this economically important ornamental plant.