Total Flower Research Articles

都市内残存林における９年間のヤマザクラの着花状況と消長

This paper aims to make clear the growing and flowering condition of Prunus jamasakura under succession of broadleaved evergreen forest in an abandoned coppice woodlands, for conserving the seasonal landscape and bio-diversity in urbanized area. In 2008, we conducted the follow-up survey in“Kohnosu-Yama Forest Reserve”, and compared the data collected in 1999. The results are as follows: (1) Number of P. jamasakura decreased from 272 to 235 mainly ascribed to suppressing and shading of surroundings such broadleaved evergreen trees as Castanopsis sieboldii, Neolitsea sericea, Cinnamomum camphora and Machilus thunbergii. The height of died P. jamasakura was less than 14m (average was 9.6m) and the DBH was less than 20cm (average was 14.3cm). (2) The average tree height of existing P. jamasakura increased from 11.0m in 1999 to 11.7m in 2008, and the DBH also increased from 20.9cm in 1999 to 25.0cm in 2008. The most growing tree's height and DBH increased 6.5m and 13.7cm respectively. (3) Total flowering somewhat decreased in 2008 compared in 1999. (4) Removing the surrounding evergreen trees by volunteer activity was effective for encouraging P. jamasakura.

Flowering habits study on pomegranate: effect of flower thinning and zinc spry on perfect flower percentage and yield of some local pomegranate cultivars

This research was carried out using three local cultivars of pomegranate (Salemi, Rawa seedless and Gelawi) for the growing seasons (2000–2001). Two studies were performed, the first study dealed with the flowering habits on the fruiting units, intension, the percentage of perfect and male flowers during flowering period, while the second study dealed with the effect of flowers thinning during the last cycle of flowering which take place during the period from 20 may to 30 june and foliar sprays of Zn at a concentration of 1 & 2% which carried out on (1/ 7/ 2000 and 1/ 10/ 2000) the objective of this studies was to increase the percentage of perfect flowers in the following season and its effect on the yield . The experimental results shows the following: 1. The male flowers were exist before the perfect flowers by 10 days and then both types of flowers were increased at interected cycles to reach the highest intension during the period (10 April to 30 June). The percentage of perfect flowers was 86.25 % at the first cycle of flowering while the second cycle formed the remaining percentage which is 13.75% and the number of male flowers were higher than the perfect flowers at a ratio of (2.10–2.81). 2. There are a significant differences in number of total flowers, perfect flowers and male flowers between cultivars. Rawa seedless cultivars was the highest in number of total flowers while the Gelawi cultivar was the highest in the percentage of perfect flowers. In spit of the deffernces in the percentage of formed flowers on fruiting units from cultivar to another, they are all appered on small shoot (spur) with one or two years old and they reached the percentage of (23.73, 37.74, 38.52%) for the three cultivars on the new shoots, shoot 1-2 years old respectively. 3. The results showed that flowers thining of hast cycle of flowering, causes a significant increases on the percentage of perfect flowers and on the percentage of fruits set in the following season (2001) at a ratios of (6.89%, 5.34%) for both characters respectively, while the increament was (3.23% and 3.40%) when Zn at 2% and the effect was increased when there is an interaction between thining and appling Zn. 4. Thining and folair sprays of Zn causes a reduction in fruit weight at a ratio of (2.1% and 1.3) respectively, while this reduction was not in parrall with the increament in the percentage of perfect flowers and the percentage of fruits set. which causes an increases in total yield up to a percentage of 10.76% when thining was done, 2.37% when Zn was sprayed and the increament reached 16.40% with the interaction between them.

Effects of Cooling Temperature and Duration on Flowering of the Nobile Dendrobium Orchid

The effects of cooling temperature [constant (10, 13, 15, or 18 °C, or 15, 18, or 21 °C)] and duration (2, 3, 4, 5, or 6 weeks, or 3, 4, 5, 6, or 7 weeks) at two separate locations (College Station and Weslaco, TX) on growth and flowering of Dendrobium Sea Mary ‘Snow King’, a Dendrobium nobile Lindl. hybrid, were investigated and the cooling requirement for flowering was quantified. Interactions between temperature and cooling duration were significant on time required to reach anthesis from either the beginning or completion of cooling, average flower number per flowering node, and percentage of nodes with aborted buds. Increasing cooling duration from 2 to 6 or 3 to 7 weeks resulted in less time to reach anthesis after the completion of cooling. However, the increased cooling durations extended the time needed for producing a flowering crop. Plants cooled at a relatively higher temperature among 10, 13, and 15 °C required less time to reach anthesis after the completion of cooling. Plants had more flowering nodes and total flowers when cooled at 10, 13, or 15 °C than at 18 °C in College Station or at 15 or 18 °C than at 21 °C in Weslaco. The results suggest that 3 weeks at 13 °C has saturated the cooling requirement, and 3 weeks at 13 or 15 °C is a recommended cooling treatment that saves production cost without retarding flower development.

Effects of Fall Fertilization on Freeze Resistance, Flowering, and Growth of ‘Hinodegiri’ Azalea

Abstract Five fertigation treatments were initiated August 1, 2002: 1) no additional fertilizer, 2) N at 75 mg·L−1 from August 1 to September 29, 3) N at 125 mg·L−1 from August 1 to September 29, 4) N at 75 mg·L−1 from August 1 to November 28, and 5) N at 125 mg·L−1 from August 1 to November 28. Freeze resistance of stems and leaves was analyzed monthly, November to February. Flower counts began prior to budbreak, and continued to flower expression. Fall fertigation increased azalea leaf and stem dry weights (DWs) compared to azaleas that received no additional fertigation after July 31. Fertigation N applied at 75 or 125 mg·L−1 from August 1 to November 28 did not increase leaf or stem DWs compared to plants fertigated at the same N rate from August 1 to September 29. High N treatments (N at 125 mg·L−1 from August 1 to September 29 or November 28) increased above ground DW, but reduced stem freeze resistance in November and March compared to plants that received N at 75 mg·L−1 from August 1 to September 29. Early flower budbreak and decreased total flower production resulted when N was applied at 125 mg·L−1 from August 1 to November 28 compared to 75 mg·L−1 from August 1 to September 29.

Biologia reprodutiva de Acacia mearnsii De Wild.: receptividade de estigmas

O objetivo deste trabalho foi analisar a receptividade de estigmas de Acacia mearnsii De Wild. em 20 árvores da Área de Produção de Sementes (APS) da Fazenda Locatelli, da empresa SETA S.A., no município de Butiá (RS) e comparar os períodos de receptividade de estigmas e de viabilidade polínica em diversas fases da abertura floral. Foi utilizado como método de colorimetria o reagente de Baker para indicar a receptividade e a viabilidade. As análises foram conduzidas em delineamento inteiramente casualizado e a estatística χ2 foi utilizada para verificar a significância dos eventos estudados. Foi observada receptividade no início da abertura floral (71%), alcançando a total receptividade (100%) em plena antese. A viabilidade polínica foi detectada no início da antese (77%) e em total abertura floral (88%). Na fase de senescência foram observados estigmas receptivos (50%) e políades viáveis (23%). Há sobreposição da fase de viabilidade masculina e de receptividade feminina, aumentando as chances de autopolinização. Na maioria das árvores analisadas (85%) foi observada a total receptividade (100%) nos estigmas amostrados. Em três árvores (15%) observou-se uma média inferior a 95% de estigmas receptivos. Não foi observada diferença significativa pelo teste do χ2 na receptividade dos estigmas no germoplasma analisado, sugerindo que o genótipo não interfere diretamente para a receptividade dos estigmas.

Timing of Nutrient Termination and Reapplication for Growth, Flower Initiation, and Flowering of the Nobile Dendrobium Orchid

Hybrids of Dendrobium nobile Lindl. have high potential to become a high-value pot plant, but detailed research to support the development of commercial production protocols was lacking. A 3 × 5 factorial experiment was conducted to investigate the effects of nutrient termination date (1 Aug., 1 Sept., or 1 Oct.) and nutrient reapplication time (at the beginning or in the middle of cooling, immediately after or 2 weeks after the completion of cooling, or no nutrient reapplication) on growth and flower development of Dendrobium Sea Mary ‘Snow King,’ a D. nobile hybrid. Interaction between nutrient termination date and reapplication time on growth and flowering was nonsignificant for all variables measured, and reapplication time had only a minor effect on leaves remaining. Regardless of nutrient reapplication time, delaying nutrient termination date resulted in improved growth and flowering. Nutrient termination on 1 Oct. resulted in taller plants with more nodes, leaves remaining, flowering nodes, and total flowers as well as fewer aborted flowers than an earlier termination date. Nutrient supply until 1 Oct. did not lead to differences in time required for anthesis but extended the time needed to reach full flowering by 1.5 d. The results suggest that flower development benefited more from the nutrients that were accumulated in mature pseudobulbs before nutrient termination rather than from those being taken from the reapplied fertilizers. Only lateral buds protruding 2 mm or more from the pseudobulb surface showed differentiated floral structures when examined histologically. The buds, excised 4 weeks after cooling treatments began, showed that nutrient termination on 1 Aug. resulted in larger flower primordia than those ended on 1 Oct., indicating an earlier or faster flower differentiation with earlier nutrient termination. No aerial shoot formation or reversion of reproductive to vegetative buds arose as a result of either late nutrient termination or resumption of nutrient application.

A flora melitófila de uma área de dunas com vegetação de caatinga, Estado da Bahia, Nordeste do Brasil

As espécies melitófilas de uma área de caatinga foram caracterizadas quanto à morfologia e recursos florais, floração e abelhas visitantes. As coletas foram realizadas, durante quatro dias consecutivos, em fevereiro, abril, junho, agosto, outubro e dezembro/2000 (10º47'37'S e 42º49'25'W). A área foi percorrida das 06:00 às 17:00 h, seguindo dois transectos paralelos (com 450 m × 100 m e 550 m × 100 m) e distando 50 m entre si, abrangendo 10 ha. As 42 espécies melitófilas identificadas (55% da flora local) foram visitadas por 2.924 indivíduos de 41 espécies abelhas. As famílias Caesalpiniaceae e Malpighiaceae foram as mais visitadas. As espécies predominantemente visitadas por 35 espécies de abelhas, correspondendo a 78% do total de indivíduos foram: Byrsonima blanchetiana Miq., Copaifera coriacea Mart., Senna macranthera, Peltogyne pauciflora Benth., Senna gardneri (Benth.) H.S. Irwin & Barneby, Serjania comata, Mouriri pusa (Gardner), Jatropha mutabilis (Pohl.) Baill., Maytenus rigida Mart. e Turnera calyptrocarpa Urb. (24% da flora apícola). A produção de flores dessas espécies representou 95% do total. Em geral, os aspectos básicos da morfologia floral das espécies: pequenas, dispostas em inflorescências, zigomorfas, de cores alva e rosa, monoclinas e com deiscência longitudinal das anteras, não diferiram em relação à flora local, corroborando o seu caráter generalista. O predomínio de interações generalistas deve-se à abundância local de abelhas eussociais nativas (Meliponinae) e Apis mellifera. Embora a produção de flores tenha sido maior na estação chuvosa, as abelhas foram mais abundantes no período seco, indicando que o recurso não limitou a atividade das abelhas. As plantas do estrato arbustivo e herbáceo floresceram mais intensamente no período seco e chuvoso, respectivamente, gerando um grau de compartimentalização no padrão de uso dos recursos pelas abelhas. Esse padrão pode favorecer a manutenção das abelhas solitárias, de pequeno porte, incapazes de competir eficientemente com abelhas eussociais com alta capacidade de comunicação e exploração dos recursos mais abundantes como Apis mellifera. Os resultados indicaram que não apenas a composição florística, mas a estratificação e a forte sazonalidade da floração foram determinantes da composição e do padrão local de uso de recursos pelas abelhas em caatinga.

Glyphosate induces transient male sterility in Ipomoea purpurea

Plant death is the most common effect resulting from the application of glyphosate, the active ingredient in the herbicide Roundup®. Individual seedlings of the morning glory, Ipomoea purpurea L. Roth, however, have been shown to exhibit tolerance to glyphosate, surviving after what should have been a lethal dose. Those that grow and reach reproductive maturity often exhibit deformed anthers within what appear to be normally developed flowers. Ipomoea purpurea has a mixed mating system and normally has hermaphroditic flowers that are capable of both selfing and outcrossing. The deformed anthers do not produce pollen, essentially converting a hermaphroditic flower to a female. Here we describe this morphological change and investigate the reproductive consequences of anther deformation. First, there is phenotypic variation for the propensity of an individual to exhibit male sterility through deformed anthers in response to treatment, but a series of field and greenhouse studies suggest that this variation is not genetic. The male sterility is also transient; within an individual, the frequency of flowers with deformed anthers declines over time. Although flowers with deformed anthers do not produce pollen, we observed mixed effects on female function of such flowers. In the greenhouse, flowers with deformed anthers that were hand-pollinated produced as many seeds as flowers with normal anthers, suggesting no effect on female fertility. In the field, however, plants with a higher proportion of anther deformation set significantly fewer seeds than those untreated, suggesting either reduced female fertility, or a reproductive penalty in flowers with deformed anthers due to the inability to self pollinate. Thus, the presence of this trait could alter the selfing to outcrossing ratio in populations that are sprayed with the herbicide. Individuals that exhibited a higher proportion of anther deformation also produce fewer total flowers than untreated plants, suggesting that anther deformation is part of a suite of responses to damage by glyphosate.

Gibberellin-mediated changes in carbohydrate metabolism during flower stalk elongation in tulips

We investigated the effects of a gibberellin synthesis inhibitor (ancymidol) and gibberellin (GA4+7) on carbohydrate metabolism and elongation in internodes of the tulip (Tulipa gesneriana L.) flower stalk during greenhouse growth. During the initial stages of flower stalk growth, the lowermost internode was mainly responsible for total flower stalk length, whereas the uppermost internode mostly contributed to total length during later stages. High concentrations of hexose sugar (mainly glucose) and increased activity of acid invertase were observed when internodes were rapidly elongating. Inhibition of gibberellin biosynthesis with ancymidol reduced the elongation rate of internodes, and inhibited the hexose sugar accumulation and acid invertase activity. Application of GA4+7 to ancymidol-treated plants reversed these effects. The degree of response to ancymidol and GA4+7 was, however, different in different internodes such that the lowermost internode was most responsive and the uppermost internode was least responsive. The results indicate that de novo biosynthesis of gibberellins is a requirement for expression of high acid invertase activity during the rapid elongation phase in tulip internodes which enables cleavage of imported sucrose to hexoses that can be readily utilized in elongating cells.

Nitrogen, Phosphorus, and Potassium Requirements for Optimizing Growth and Flowering of the Nobile Dendrobium as a Potted Orchid

Experiments were conducted to determine how nitrogen (N), phosphorus (P), and potassium (K) rate and fertilizer termination time affect the growth and flowering of a Dendrobium nobile Lindl. hybrid, Dendrobium cv Red Emperor ‘Prince’. Nitrogen, P, and K were tested in separate experiments as a factorial combination of five rates and three termination dates (1 Sept., 1 Oct., and 1 Nov. 2005). Nitrogen and K rates were 0, 50, 100, 200, and 400 mg·L−1. Phosphorus rates were 0, 25, 50, 100, and 200 mg·L−1. Levels of the nutrients not being tested were held constant. For all nutrients, ending fertilization on 1 Sept. resulted in greater or similar pseudobulb thickness compared with ending fertilization on 1 Oct. or 1 Nov. Pseudobulbs grew taller as the N rate increased, peaking at 100 and 200 mg·L−1. There were interactions between the N rate and fertilizer termination time on all reproductive characteristics. For all fertilizer termination times, flower number increased once N was applied. When ended on 1 Nov., 200 and 400 mg·L−1 N caused a delay to reach anthesis. All P rates resulted in taller plants with equally more nodes when compared with 0 mg·L−1. As the K rate increased from 0 to 100 mg·L−1, plant height increased, with no further increase at higher rates. The number of leaves remaining increased as N and K rates increased up to 200 mg·L−1. Total flower number and flowering node number increased as the K rate increased to 100 mg·L−1 (terminated on 1 Sept.) or 50 mg·L−1 (terminated on 1 Oct. or 1 Nov.). In the fourth experiment, only N was ended at four termination times, whereas all other nutrients continued to be supplied until flowering. Control plants received all fertilizer elements until flowering. The duration of N application did not affect vegetative or flowering characteristics. No aerial shoots were observed as a result of prolonged application of N at all rates. In summary, 100 mg·L−1 N, 25 mg·L−1 P, and 100 mg·L−1 K are recommended for optimal vegetative growth and reproductive development of Dendrobium cv Red Emperor ‘Prince’.

Relationships between flowering phenology and female reproductive success in the Japanese tree species Magnolia stellata

We have examined the earliness, duration, and amplitude of flowering genets in a Magnolia stellata (Sieb. et Zucc.) Maxim. population in relation to their size, environmental factors (temperature and light), and female reproductive success (ovule survival rate) over three consecutive years. Average flowering durations of individual flowers, genets, and the whole population in these 3 years were 10.2, 15.2, and 29.0 d, respectively. A bisexual phase (with both female and male phase flowers) in genets spanned 62.9% of the total flowering period, suggesting that geitonogamy can occur. The earliness, duration, and amplitude of flowering genets were all significantly correlated, indicating that genets flower early and long periods have high flowering amplitudes. The three parameters were also significantly correlated with the size of the genets (represented by the diameter at breast height of its thickest ramet) and relative photosynthetic photon flux density at the top of their crowns. Therefore, genets that are large and located in well-lit sites tend to have many flowers, and blossom both earlier and longer. Later-flowering genets have higher female reproductive success, probably because M. stellata is protogynous. Significantly positive correlation between flowering amplitude and female reproductive success suggests that large numbers of flowers increase the attractiveness of genets for pollinators, and this outweighs the negative effects of geitonogamy.

Phytogeography, endemism and affinities of the flora of new Amarambalam Reserve Forests in the Western Ghats of India

Floristic analysis of New Amarambalam Reserve Forests, situated in the Western Ghats of India and forming part of Nilgiri Biosphere Reserve, based on surveys conducted during 1997-2000, has been presented in the paper. The forest area extents to about 265 km2, at an altitudinal range of 40-2600 m above msl. The area is the abode of almost all the forest types of the Indian Peninsula, preserved in an almost pristine state. Intensive floristic survey of the area recorded of a total of 1135 taxa of angiosperms, which belonged to 136 families and 644 genera. The flora is composed of 78 per cent dicotyledons and 22 per cent monocotyledons. Phytogeographical analysis of the flora revealed very high endemism, and almost 21 per cent of the total flowering plants recorded from there were those endemics to Western Ghats of India. Among them, 12.5 per cent were species restricted to Southern part of the Western Ghats. Peninsular Indo-Sri Lankan elements represented 15 per cent of the total flora, which demonstrates the affinity of the region with that of the adjacent ocean Island. Regarding the pattern of distribution of various species outside India, 66 per cent of them were of Indo-Malayan and South and South-East Asian range and 30 per cent of the total flora were composed of pluri-regional species or wides. There were only four per cent taxa in the flora, which are either exotic weeds or escapes from cultivation, showing the less disturbed status of the vegetation.

Benzyladenine Promotes Flowering in Doritaenopsis and Phalaenopsis Orchids

Two experiments were performed to determine how application of the cytokinin benzyladenine (BA) influenced flowering in Doritaenopsis and Phalaenopsis orchid clones. In the first experiment, two vegetative orchid clones growing in 15-cm pots were transferred from a 28°C greenhouse that inhibited flowering to a 23°C greenhouse for flower induction (day 0). A foliar spray (0.2 L m−2) containing BA at 100, 200, or 400 mg L−1 or 25, 50, or 100 mg L−1 each of BA and gibberellins A4 + A7 (BA+GA) was applied on days 0, 7, and 14. Plants treated with BA alone at 200 or 400 mg L−1 had a visible inflorescence 3–9 days earlier and had a mean of 0.7–3.5 more inflorescences and 3–8 more flowers per plant than nontreated plants. The application of BA+GA had no effect on inflorescence number and total flower number at the rates tested. In the second experiment, three orchid clones received a single foliar spray of BA at 200 mg L−1 at six time points relative to time of transfer from 29°C to 23°C (−1, 0, +1, +2, +4, or +6 weeks). A separate group of plants received a BA application at week 0 but was maintained at 29°C. Inflorescence number was greatest in all three orchid clones when plants were treated with BA 1 week after the temperature transfer. Plants that were sprayed with BA and maintained at 29°C did not initiate inflorescences. The promotion of flowering by the application of BA suggests that cytokinins at least partially regulate inflorescence initiation of Doritaenopsis and Phalaenopsis, but its promotion is conditional and BA application cannot completely substitute for an inductive low temperature.

Flower Sex Expression in Lychee (Litchi chinensisSonn.) Is Affected by Gibberellic Acid and Naphthalene Acetic Acid

ABSTRACT Gibberellic acid (GA3) at 25, 50, and 100 mg-L−1 and naphthalene acetic acid (NAA) at 20, 40, and 80 mg-L−1 were sprayed to runoff on flower panicles of 15-year-old lychee trees one week after panicle emergence. Trees sprayed with water only were used as the control. The number of male flowers was increased quadratically by NAA compared to the control in 2000, and 2001. The number of hermaphrodite flowers functioning as female (HF-F) and the number of hermaphrodite flowers functioning as male (HF-M) was reduced quadratically by all concentrations of NAA both years. The greater the NAA concentration, the greater the reduction. The total number of flowers was also reduced by all NAA concentrations both years. Fruit set (percentage of total HF-F flowers) was reduced quadratically by NAA in 2001, but had no effect in 2000. The number of male flowers was increased quadratically by GA3 both years. Regression analysis also showed a positive relationship between GA3 and HF-F flowers both years. However, hermaphrodite flowers functioning as male (HF-M) was reduced quadratically by GA3 both years. In addition, the total number of flowers and fruit set was increased quadratically by GA3 both years. GA3promotion of male flowers, HF-F production, and increased fruit set may have important bearing on yield improvement.

Stress‐induced dynamic adjustments of reproduction differentially affect fitness components of a semi‐arid plant

Summary 1. Summer drought stress is considered the primary constraint to plant performance in Mediterranean ecosystems. However, little is known about the implications of summer stress for plant reproduction under real field conditions and, particularly, for the regulatory mechanisms of maternal investment in reproduction. 2. The relationship between plant physiological status at different reproductive stages over the course of the summer drought period and final reproductive output was modelled in the Mediterranean semi-arid specialist Helianthemum squamatum. 3. Plant physiological status, assessed by the chlorophyll fluorescence-based parameter F v / F m , and soil moisture content beneath each plant, were determined in the field at five key phenological moments in a total of 88 plants. We used Generalized Linear Mixed Models to evaluate the effect of plant physiological status at those different dates on several components of reproduction (number of flowers and seeds per plant, fruit-set and intra-fruit seed abortion). We included soil moisture as an additional predictor to statistically control its potential effect on reproduction. 4. F v / F m measured at midday was a significant predictor of reproductive output, but its significance varied over time and with the specific reproductive response variable. F v / F m measured at the onset of flowering was positively related to the number of flowers and seeds per plant, whereas F v / F m at the fruiting peak positively affected fruit-set. Soil moisture content was only significant when measured before flowering, being positively related to total flowers and seeds. The effect of stress on reproductive output acted either at an early stage of the reproductive season, by varying the number of flowers produced and seed primordia initiated, or at a later stage, by adjusting the number or ripe fruits. 5. Synthesis . Our results show a direct relationship between physiological status and reproduction, and highlight the importance of the timing of stress for reproductive success. They also show that small departures from the physiological optimum at specific reproductive stages may cause significant decreases in the reproductive output. We suggest that the dynamic adjustment of reproduction in response to stress is adaptive in fluctuating and unpredictable Mediterranean semi-arid environments, where an adequate temporal distribution of maternal resources determines the species’ ability to withstand severe environmental conditions.

Flowering synchrony and floral display size affect pollination success in a deceit-pollinated tropical orchid

Due to frequency-dependent negative selection, a strong relationship between reproductive phenology traits and pollination success is expected in deceit-pollinated species. This paper assesses the effects of floral display size on both female (fruit production) and male (pollen removal) pollination success in a population of the deceit-pollinated tropical orchid Myrmecophila christinae during two consecutive years (1998–1999). Low pollen removal (∼9% of total flowers) and fruit production values (∼3% of total flowers) were recorded during both years. As expected, binary logistic regressions showed a significant negative effect of floral synchrony, and a positive effect of floral display size on both male and female success, although these effects varied across years. Pollination rates in the field and in hand pollinations suggest a doubling in pollinator abundance between years. Results suggest that floral display size and flowering synchrony are of adaptive value for M. christinae. However, between-year fluctuations might indicate that reproductive phenology traits in deceit-pollinated species undergo fluctuating selection regimes among years and are probably linked to short-term changes in environmental (abiotic and biotic) conditions.

Determination of productivity and fruit set ratios of various loquat (Eriobotrya japonica) cultivars under Mediterranean conditions

This study was conducted to determine fruit set ratios and productivity of four loquat (Eriobotrya japonica) cultivars, ‘Gold Nugget’, ‘Kanro’, ‘Baffico’, and ‘Dr. Trabut’ on the coast of the Mediterranean region of Turkey between 2001 and 2003. Elevation of the experimental site was c. 158m, with an average annual temperature of 19°C and annual rainfall of 556 mm (average of 1983–2003). To determine fruit set, a branch was randomly selected from all four directions on each tree. Approximately 250–300 flower buds were counted before the blossom at each of these selected branches making a total of c. 1000–1200 flower buds on each tree. Percent blossom ratios, % initial fruit set, and % final fruit set were determined during the experimental period. Furthermore, productivity of the cultivars was calculated by the proportion of the total flower buds to the final fruit amount. The relation between minimum, maximum, and average temperature values as well as relative humidity and precipitation between October and February, which covers blossom periods and fruit set ratios, were also examined by correlation. Our results showed that the highest rates for the above‐mentioned properties were taken in 2002 except % blossom, the highest rates were for ‘Gold Nugget’ for the other three properties. According to 3‐year averages, ‘Gold Nugget’ showed higher rates on initial fruit set, final fruit set, and productivity (12.39%, 11.03%, and 10.22%, respectively). Percent initial fruit set was between 6.98% and 9.70%, % final fruit set was between 5.66% and 7.55%, and productivity was between 5.33% and 6.94% for the other three cultivars.

Pollination in small islands by occasional visitors: the case of Daucus carota subsp. commutatus (Apiaceae) in the Columbretes archipelago, Spain

This study investigates the pollination ecology and related floral traits of the species Daucus carota subsp. commutatus in the isolated archipelago of Columbretes, E. Spain, where bees are absent. Two populations were studied: a small population found on a relatively large island (Grossa) inhabited nowadays by three people; and a larger population on a smaller uninhabited island (Foradada). The plant, found also in other rocky coastal enclaves of the west Mediterranean, is totally self-compatible, andromonoecious, exhibiting strong protandrous dichogamy and sequential flowering of umbel orders, with limited probability of self pollination at the plant level. Pollination on both study islands is carried out solely by flies, mainly by Eristalis tenax (Syrphidae), a long distance visitor and efficient pollinator, but irregular migrant to the archipelago; and Lucilia sericata (Calliphoridae), an abundant flower visitor but less efficient pollinator dependent on human and avian wastes for its larval growth. The small population on Grossa appears not to suffer pollen limitation. Seed set is reduced, however, in the large population on Foradada, which we attribute to the low pollinator capital of this island, which is too small to attract and sustain migrant hoverflies and where no human and avian wastes are available to sustain blowfly growth. We conclude that in isolated environments with reduced or unpredictable pollinator capital, long distance migrant pollinators, such as E. tenax, play an invaluable conservation and perhaps evolutionary role for the native plants. Because these islands have been always practically uninhabited we argue that the absence of adequate local pollinator capital is perhaps compensated by the selection of particular floral traits, which differentiate the study subspecies from other conspecifics. Such traits are: the exposure of nectar during male versus female stage to enhance quick pollen flow; the extended stigma receptivity period (up to 10 days) resulting in a total flower life span of up to 22 days, enabling an adequate pollen deposition on stigmas even under low pollen transfer rates. In this respect, the low flower sex ratio (hermaphrodite: staminate) compared to other conspecifics studied elsewhere may be also relevant.

Efeito de giberelina (GA3) e do bioestimulante 'Stimulate' na indução floral e produtividade do maracujazeiro-amarelo em condições de safra normal

O objetivo do trabalho foi avaliar os efeitos de GA3, nas concentrações de 100; 200 e 300mg L-1 e do bioestimulante Stimulate®, em doses de 2,08; 4,17 e 6,25mL L-1, em duas aplicações via foliar, acrescidas de espalhante adesivo Silwett® a 0,05% e a exposição dos ramos à luminosidade, na indução floral e produtividade do maracujazeiro-amarelo, em condições de safra normal, em Araguari-MG. Aos 30 dias após a primeira aplicação dos tratamentos, iniciaram-se as avaliações do número de flores, com contagens diárias, nos dois lados da espaldeira, nos meses de setembro de 2002 a março de 2003. As colheitas dos frutos foram realizadas semanalmente, no período de novembro de 2002 a abril de 2003, observando-se a produção. O GA3 e o Stimulate não proporcionaram efeito significativo no número de flores, nas sete épocas, assim como no número total de flores. Não houve efeito dos tratamentos para a produtividade e produção total de frutos. Os ramos sob luminosidade pela tarde apresentaram maior número de flores, nos meses de setembro, dezembro, fevereiro e março. A interação entre os tratamentos e a exposição dos ramos à luminosidade não foi significativa para o número de flores, nas épocas avaliadas.

Revisiting dogwood anthracnose in Illinois

Dogwood anthracnose (Discula destructiva) was first discovered in Illinois in 1995 at Dean Hills Nature Preserve, Fayette County. In the original study, individuals of flowering dogwood (Cornus florida) showed a 97% increase in infection by dogwood anthracnose between July 1995 and August 1996. As all size classes of flowering dogwood were infected, it was predicted that the disease would probably cause the extirpation of this species at the site. Though not extirpated, flowering dogwood has not recovered from the initial infection (1995), when 3475 healthy stems/ha were encountered. Since that initial study, total flowering dogwood stems recorded for the site ranged from a low of 110 stems/ha in 1996, to 540 stems/ha in 2002, and 345 stems/ha in 2004.