Greater Number Of Flowers Research Articles

Competition versus facilitation: conspecific effects on pollinator visitation and seed set in the iris Lapeirousia oreogena

Ecological interactions between conspecific plants can range from facilitative to competitive depending on the spacing and abundance of individuals. Competitive interactions are expected when plants flower en‐masse and availability of pollinators is limited. We tested this prediction using Lapeirousia oreogena, a mass‐flowering South African iris that is pollinated by a single species of long‐proboscid fly. Controlled hand‐pollination experiments showed that L. oreogena is self‐compatible, but reliant on pollinator visits for seed set. Seed production per flower showed a significant negative relationship with patch size (and the correlated measure of number of individuals per patch), but was not affected by flower density or distance to neighbouring patches. There was a tendency for fly abundance to increase with patch size, but the rate of visits to individual flowers by flies was not affected by patch size. Seed set of hand‐pollinated flowers did not differ for plants in and out of dense patches, indicating that the large differences in seed set among patches were likely to reflect pollinator visits, rather than the genetic or physiological capacity of plants to produce seeds. The reduced fecundity of L. oreogena in large patches with a greater numbers of flowers is consistent with the idea that plants with highly specialized pollination systems can experience intra‐specific competition for pollination.

Overexpression of TaNHX2 enhances salt tolerance of ‘composite’ and whole transgenic soybean plants

Salinity is a major factor resulting in extensive loss of agricultural production. Genetic transformation has become a powerful tool for studying gene function and for improving crop salt tolerance. In this study, a TaNHX2 gene was transformed into a plant cloning vector under the control of cauliflower mosaic virus 35S promoter, and then introduced into Agrobacterium rhizogenes strain K599. Explants of soybean were transformed with A. rhizogenes and ‘composite’ plants consisting of wild-type shoots and transgenic hairy roots overexpressing TaNHX2 were produced. When exposed to salt stress, ‘composite’ plants displayed high salinity tolerance at 171 mM NaCl in vermiculite and in solid medium supplemented with up to 200 mM NaCl, whereas control plants displayed chlorosis and died within 15 days under above treatment conditions. We subsequently obtained soybean plants overexpressing TaNHX2 through A. tumefaciens-mediated transformation and studied four homozygous lines of TaNHX2. Transgenic lines displayed an enhanced salt tolerance in plant biomass and flower number per plant, compared with wild type plants grown on sand culture containing 150 mM NaCl. Furthermore, transgenic plants of line C12-11 showed longer survival, less growth inhibition and greater number of flowers than wild type plants. Taken together, these results indicated that TaNHX2 gene could enhance salt tolerance of soybean, and A. rhizogenes-mediated transformation system could be used as a complementary tool of A. tumerfaciens-mediated transformation to rapidly investigate candidate gene function in soybean.

Wendlandia tinctoria (Roxb.) DC. (Rubiaceae), a key nectar source for butterflies during the summer season in the southern Eastern Ghats, Andhra Pradesh, India

Wendlandia tinctoria is a semi-evergreen tree species. It shows massive flowering for about a month during March-April. The floral characteristics such as the white colour of the flower, lack of odour, short-tubed corolla with deep seated nectar having 15-18% sugar concentration are well tailored for visitation by butterflies. The nectar is hexose-rich and contains the essential amino acids such as arginine and histidine and the non-essential amino acids such as alanine, aspartic acid, cysteine, glysine, hydroxyproline, tyrosine, glutamic acid and serine. The inflorescences with clusters of flowers provide an excellent platform for foraging by butterflies. The flowers are long-lived and attractive to butterflies. A variety of butterflies visit the flowers for nectar and in doing so, they pollinate them. Nymphalids are very diverse and utilize the flowers until exhausted. The flowers being small in size with a small amount of nectar compel the butterflies to do a more laborious search for nectar from a greater number of flowers. But, the clustered state of the flowers is energetically profitable for butterflies to reduce search time and also flight time to collect a good amount of nectar; such a probing behaviour is advantageous for the plant to achieve self- and cross-pollination. Therefore, the study shows that the association between W. tinctoria and butterflies is mutual and such an association is referred to as psychophilous. This plant serves as a key nectar source for butterflies at the study site where floral nectar sources are scarce during the summer season.

SAFFRON STIGMAS PRODUCTION AS AFFECTED BY SOIL TEXTURE

Saffron is considered a species that prefers sandy soils, but in many environments it is cultivated on silt soil or on drained clay soil. To evaluate the effect of soil texture on saffron production, corms of a Sardinian population (Italy) were sowed in the same piece of land on three different soil textures obtained mixing an increasing quantity of sand to a silt-clay soil: sand, intermediate and clay. Two corms densities (55 and 33 corms/m 2 ) in plots four times replicated were also applied. Flower calendar, daily flower number and total stigmas weight were determined. Soil temperature was also measured. The flower calendar was partially affected by soil texture: flowering started on the same day for all the treatments, but in sand soil flowering ended 3 and 5 days later compared to intermediate and clay treatments respectively. Flower number and stigmas weight were significantly affected by soil texture and corm density: the greatest number of flowers and the highest total stigmas weight were found in sand soil with values +10% and +38% higher than intermediate and clay treatments, respectively. The highest corms density, that obviously determined a higher flower and stigmas production, resulted in the best production performance in both sand and intermediate soil conditions, while clay soil did not allow any increase in saffron production compared to the lowest density.

Isopentenyl transferase gene (ipt) downstream transcriptionally fused with gene expression improves the growth of transgenic plants

This research reports a promising approach to increase a plant's physiological cytokinin content. This approach also enables the increase to play a role in plant growth and development by introducing the ipt gene to downstream transcriptionally fuse with other genes under the control of a CaMV35S promoter, in which the ipt gene is far from the 35S promoter. According to Kozak's ribosome screening model, expression of the ipt gene is reduced by the terminal codon of the first gene and the internal untranslated nucleotides between the fused genes. In the transgenic plants pVKH35S-GUS-ipt, pVKH35S-AOC-ipt, and pVKH35S-AtGolS2-ipt, cytokinins were increased only two to threefold, and the plants grew more vigorously than the pVKH35S-AOC or pVKH35S-AtGolS2 transgenic plants lacking the ipt gene. The vigorous growth was reflected in rapid plant growth, a longer flowering period, a greater number of flowers, more seed product, and increased chlorophyll synthesis. The AOC and AtGolS2 genes play a role in a plant's tolerance of salt or cold, respectively. When the ipt gene transcriptionally fuses with AOC or AtGolS2 in the frame of AOC-ipt and AtGolS2-ipt, slight cytokinin increases were obtained in their transgenic plants; furthermore, those increases played a positive role in improvements of plant growth. Notably, an increased cytokinin volume at the physiological level, in concert with AtGolS2 expression, enhances a plant's tolerance to cold.

Influência de déficits hídricos controlados na uniformização do florescimento e produção do cafeeiro em três diferentes condições edafoclimáticas do Estado de São Paulo

O objetivo foi avaliar a influência de déficits hídricos controlados no florescimento e na produção de cafeeiro Arábica (Coffea arabica L. cv. Obatã enxertados sobre C. canephora cv. Apoatã) em três diferentes condições edafoclimáticas do Estado de São Paulo. As plantas, com idade inicial de 2,5 anos foram cultivadas em espaçamento 2,5 x 1,0 m, no período de julho de 2001 a maio de 2002, nas localidades paulistas de Adamantina, Mococa e Campinas, sob as seguintes condições de manejo de água: não-irrigado (NI), irrigado continuamente (IC) e irrigados com suspensão da irrigação por 30 dias em julho (I30) e 60 dias em julho e agosto (I60). Independentemente da localidade, nos três tratamentos irrigados (IC, I30 e I60) houve maior produção de cafés por planta em relação às plantas não irrigadas (NI), sendo as maiores diferenças signi4ficativas observadas em Mococa. O tratamento I60 favoreceu a obtenção de déficits hídricos da ordem de -1,1 MPa em Adamantina, -1,6 MPa em Mococa e -1,2 MPa em Campinas, os quais foram mais efetivos na sincronização das floradas do cafeeiro aliando uniformidade com alta produção. O maior número de floradas e a baixa uniformidade de produção das plantas irrigadas continuamente (IC) confirmam a necessidade de um período de seca na sincronização do florescimento. Os baixos valores de potencial da água (Ψwa) nas folhas (-2,5 a -2,8 MPa) das plantas não irrigadas (NI) reduziram significativamente o número de flores, se comparadas às plantas irrigadas, com reflexos na produção final, indicando a necessidade de irrigação para assegurar boa iniciação floral.

Seleção de genótipos de Dendrobium phalaenopsis (Orchidaceae) nas fases de propagação in vitro e aclimatização

Normal 0 21 false false false PT-BR X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} A hibridação de orquídeas é realizada para propiciar a produção de cultivares de interesse comercial que apresentem alto vigor, grande número de fores e variabilidade de cores. O trabalho teve por objetivo a seleção de genótipos de Dendrobium phalaenopsis favoráveis para a propagação in vitro e aclimatização, resultantes de cruzamentos e autofecundações de plantas matrizes selecionadas. Foram utilizadas 56 plantas de D. phalaenopsis para a realização dos cruzamentos e autofecundações, totalizando 109 combinações. Dos 109 cruzamentos e autofecundações realizados, apenas 13 cruzamentos e 3 autofecundações apresentaram número de plântulas sufcientes para as avaliações. Após cinco meses, 15 plântulas de cada cruzamento e autofecundação foram submetidas à avaliação das características: comprimento da parte aérea, número de raízes, peso da massa fresca total, comprimento da maior raiz e número de brotações. As demais foram plantadas em bandejas de isopor e após quatro meses foi avaliado a taxa de sobrevivência. O genótipo mais favorável para propagação in vitro e aclimatização foi o cruzamento DF18 x DF13.

Effect of mother corm dimension and sowing time on stigma yield, daughter corms and qualitative aspects of saffron (Crocus sativus L.) in a Mediterranean environment

AbstractBACKGROUND: Saffron is one of the most appreciated and expensive spices known and has been used from the oldest times as a dye for fabrics, a condiment to enrich food and for medicinal purposes. The aim of this study was to evaluate the effect of crop management methods on the quantitative and qualitative characteristics of the spice in southern Italy. Two sowing times (end of July and end of August) and two corm dimensions (4 and 3 cm horizontal diameter) were evaluated.RESULTS: Flowering period and duration were not influenced by the studied factors, while early sowing time and greater corm dimension resulted in a greater number of flowers per m2, increased stigma yield and a greater total yield of replacement corms. Early sowing time also showed a significant positive influence on stigma quality measured as apocarotenoid content according to ISO guidelines.CONCLUSION: The results show that, in a Mediterranean environment, appropriate crop techniques and selection of corms can result in economic levels of production and improve the quantitative and qualitative characteristics of saffron. In fact, according to their apocarotenoid contents, samples from the early (July) and late (August) sowing times belonged to the first and second ISO categories respectively. Copyright © 2008 Society of Chemical Industry

A water deficit during pod development in lentils reduces flower and pod numbers but not seed size

An experiment was conducted under controlled conditions in a glasshouse to determine the sensitivity of reproductive development of lentil (Lens culinaris Medikus) genotypes of different origins to water deficit. The 3 genotypes were Cassab (West Asia), Simal (South Asia), and ILL 7979 a crossbred between a West Asian genotype and a South Asian genotype. Two watering treatments, a well-watered control and a water-deficit treatment, were imposed from the beginning of podding. Leaf water relations, total dry matter production, leaf area, and number of flowers, pods, and seeds were measured from podding to maturity. In the well-watered plants the leaf water potential (ψleaf) before sunrise ranged from −0.6 to −0.8 MPa. When subjected to water deficit, ψleaf fell to about −3.0 MPa. Genotypes did not show variation in vegetative growth or seed yield under either well-watered or water-deficit conditions, but they differed significantly in the number of flowers, fruiting nodes, pods, and seeds, and harvest index (HI). Seed size in Cassab was 61% larger than ILL 7979 and 105% larger than Simal. The small-seeded genotypes produced the highest number of fruiting nodes and hence a greater number of flowers, pods, and seeds. Seed size was positively correlated with seed growth rate (r = 0.77**) and seed fill duration (r = 0.45*). The water deficit reduced plant height by about 20%, leaf area by 48–81%, and total dry matter by about 60% compared with well-watered plants. The water deficit reduced flower number by 35–46% and increased seed abortion (empty pods) by 17–46%. The water deficit had no effect on the maximum seed growth rate, seed fill duration, or final seed size in any of the 3 genotypes. Therefore, the 70% reduction in seed yield induced by the water deficit was primarily due to a reduction in pod and seed numbers (by 59–70%) rather than individual seed growth rate and seed size.

EFFECT OF FOOD REDUCTIONS ON TERRITORIAL BEHAVIOR OF PURPLE-THROATED CARIBS

Abstract We experimentally reduced the number of flowers of two species of Heliconia (H. caribaea and H. bihai) by 50% on territories defended by male Purple-throated Caribs (Eulampis jugularis). Following reductions, males decreased the amount of time they spent feeding on their territories and lost a significant amount of weight, but increased their time feeding and regained weight to premanipulation levels following restoration of flower abundance. Territorial males also spent less time in defense following flower reductions, in part by reducing the durations of chases of female intruders. Significantly fewer females intruded onto male territories following reductions in only 1 of 3 years; in all 3 years, significantly more females intruded onto the more rewarding H. caribaea territories, which offered a greater number of flowers per inflorescence than H. bihai territories. Efectos de la Disminucion de la Cantidad de Alimento sobre el Comportamiento Territorial de Eulampis jugularis Resumen. Disminuimo...

Elevated sucrose-phosphate synthase activity in transgenic tobacco sustains photosynthesis in older leaves and alters development.

Constitutive over-expression of a maize sucrose-phosphate synthase (SPS) gene in tobacco (Nicotiana tabacum) had major effects on leaf carbohydrate budgets with consequences for whole plant development. Transgenic tobacco plants flowered earlier and had greater flower numbers than wild-type plants. These changes were not linked to modified source leaf carbon assimilation or carbon export, although sucrose to starch ratios were significantly higher in leaves expressing the transgene. The youngest and oldest leaves of plants over-expressing SPS had up to 10-fold wild-type maximal extractable SPS activity, but source leaf SPS activities were only 2-3 times greater in these lines than in the wild type. In the oldest leaves, where the expression of the transgene led to the most marked enhancement in SPS activity, photosynthesis was also increased. It was concluded that these increases in the capacity for sucrose synthesis and carbon assimilation, particularly in older leaves, accelerate the whole plant development and increase the abundance of flowers without substantial changes in the overall shoot biomass.

Growth and Flowering of Lantana camara L. subsp. camara as Affected by Triapenthenol and Environmental Factors

The various concentration effects of the growth regulator triapenthenol (0, 43.75, 87.5, 175, and 350 mg/pot) on the growth and flowering of Lantana camara L. subsp. camara under different shading levels (0%, 28%, and 66%) were studied in 1997 and 1998 in a glasshouse in Attica, Greece. It was found that minimum temperature and photosynthetic photon flux density were the most important factors to plant growth. The growth index (GI) decreased as the regulator concentration increased while the number of flower heads per plant increased up to a maximum at the concentration of 87.5 mg triapenthenol per pot with a decrease afterwards, at all shading levels. The interaction between shading level and triapenthenol concentration significantly affected GI and flowering of lantana plants. The growth index of the control plants increased and the number of flower heads per plant decreased significantly at all concentration levels examined, as shading increased from 0% to 66%. Triapenthenol resulted in darker green foliage and at higher concentrations in some leaf distortion. The most attractive plants were produced with triapenthenol concentration of 87.5 mg/pot at the nonshaded plot; they were small with the greatest number of flowers. Chemical name used: (E)-(RS)-1-cyclohexyl-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)-pent-1-en-3-ol (triapenthenol).

Reproductive ecology and the persistence of an endangered plant

Amsinckia grandiflora (large-flowered fiddleneck) is an extremely rare California annual wildflower, known only from three populations. We conducted field and greenhouse experiments to compare the rare heterostyle with a cryptic self-incompatibility system (A. grandiflora) to a common, self-compatible, homostylous, sympatric congener (A. tessellata). Inter-species comparisons of adult plants suggested that in the greenhouse, A. grandiflora balances low floral seed set (seeds per flower) with increased floral output (flowers / plant) and a greater number of flowers per inflorescence. Seed set from active self-, intra- and inter-morph pollinations was high in A. grandiflora, indicating that the cryptic self-incompatibility system does not prevent seed set in the species. In the field, A. grandiflora floral output was only slightly greater than for A. tessellata, and did not fully balance lower floral seed set. Amsinckia tessellata average seed weight was lower than that of A. grandiflora, which, along with the lower number of flowers produced, indicated lower maternal investment per nutlet than for A. grandi- flora. Under conditions of unlimited resources, it appears that A. grandiflora fitness is not intrinsically limited when compared to its weedy relative A. tessellata. The differences in nutlet output between A. grandiflora and A. tessellata under field conditions are more likely due to differential responses to extrinsic factors such as competition and pollinator availability.

Pollination ecology of Tabebuia aurea (Manso) Benth. & Hook. and T. ochracea (Cham.) Standl. (Bignoniaceae) in Central Brazil cerrado vegetation

The pollination ecology and breeding systems of Tabebuia aurea (Manso) Benth. & Hook., and T. ochracea (Cham.) Standl. were investigated in an area of cerrado vegetation in the Federal District of Brazil. These species occur sympatrically, flower massively and synchronously for a month, during the dry season (July to September). Both have diurnal anthesis, with similar floral structures, a yellow tubular corolla and produce nectar. Fourteen species of bees visited both Tabebuia species, but, only three Centris species and Bombus morio, were considered potential pollinators, because of their high frequency on the flowers and their efficiency in carrying pollen. Tests on the breeding systems of T. aurea and T. ochracea demonstrated that boths species are self-incompatible, with late-acting self-incompatibility. The proportion of fruit set from cross pollination (T. aurea 17.2% and T. ochracea 12.3%) in both species was low considering the great number of flowers displayed. This suggests a lack of maternal resources for fruit-set. The great amount of seeds per fruit (about 92 in T. aurea and 285 in T. ochracea) may represent an investment of maternal resources allocated on higher quality of fertilized ovules.

Can selection to escape nectar thieving force plants to portion nectar in many flowers?

There are several hypotheses which try to explain why particular plants produce just the number of flowers that they do. These hypotheses include: compromises between the attraction of pollinators and avoiding self-pollination by geitonogamy; optimal nectar production as a result of diminishing gains of nectar production; opportunity for selective abortion; or different bet-hedging strategies. In this paper, I present a hypothesis which interferes with the others concerning flower numbers in plants: nectar thieving can apply a selection force in plants which result in a portioning of nectar in many flowers. Energy saved by reducing the quantity of nectar in each flower can be directed into greater flower numbers.

Genetic control of male fertility in Arabidopsis thaliana: structural analyses of postmeiotic developmental mutants.

Seven new male-sterile mutants (ms7-ms13) of Arabidopsis thaliana (L.) Heynh. (ecotype columbia) are described that show a postmeiotic defect of microspore development. In ms9 mutants, microspores recently released from the tetrad appear irregular in shape and are often without exines. The earliest evidence of abnormality in ms12 mutants is degeneration of microspores that lack normal exine sculpturing, suggesting that the MS12 product is important in the formation of pollen exine. Teratomes (abnormally enlarged microsporocytes) are also occasionally present and each has a poorly developed exine. In ms7 mutant plants, the tapetal cytoplasm disintegrates at the late vacuolate microspore stage, apparently causing the degeneration of microspores and pollen grains. With ms8 mutants, the exine of the microspores appears similar to that of the wild type. However, intine development appears impaired and pollen grains rupture prior to maturity. In ms11 mutants, the first detectable abnormality appears at the mid to late vacuolate stage. The absence of fluorescence in the microspores and tapetal cells after staining with 4',6-diamidino-2-phenylindole (DAPI) and the occasional presence of teratomes indicate degradation of DNA. Viable pollen from ms10 mutant plants is dehisced from anthers but appears to have surface abnormalities affecting interaction with the stigma. Pollen only germinates in high-humidity conditions or during in-vitro germination experiments. Mutant plants also have bright-green stems, suggesting that ms10 belongs to the eceriferum (cer) class of mutants. However, ms10 and cer6 are non-allelic. The ms13 mutant has a similar phenotype to ms10, suggesting is also an eceriferum mutation. Each of these seven mutants had a greater number of flowers than congenic male-fertile plants. The non-allelic nature of these mutants and their different developmental end-points indicate that seven different genes important for the later stages of pollen development have been identified.

Differences in the Progression of Succesive Flowering between Summer and Autumn Ecotype Cultivars in Common Buckwheat (Fagopyrum esculentum Moench).

普通ソバ品種しなの夏そば(夏型品種)および宮崎在来(秋型品種)を夏栽培および秋栽培して, 花房および小花房内の花の位置別に開花調査し, 開花の進行状況の差異を明らかにした.しなの夏そばの夏栽培および宮崎在来の秋栽培では開花数が個体あたり600～850個で, 開花期間が約1ヶ月であったのに対して, 宮崎在来の夏栽培では開花数が2600個以上で, 開花期間が役4ヶ月にもなった.また, しなの夏そばの秋栽培では開花数199個で, 開花期間は半月にしかならなかった.宮崎在来の夏栽培では開花数が多いにもかかわらず, 結実率が極端に低かったために, 一方, しなの夏そばの秋栽培は結実率が高かったものの, 開花数が少なかったために, いずれも痩果数が少なくなった.開花期間の長かった宮崎在来夏栽培では開花期間中3回の開花数の極大期であり, 秋栽培とほぼ同時期に開花終了した.その開花後期には(1)新しい花房の発生の継続, (2)開花終了花房に蕾の再発生, (3)休眠側芽の再生長が起こった.1花房内でみても, 1小花房内での開花数が多く, 上位節花房では小花房数も多いことによって, 開花数が多く, 開花期間が長かった.また, 花房間, 小花房間および小花房内の各花間の開花期間隔が長いことによって, 開花始後の開花数増加が秋栽培より緩やかであった.しなの夏そばの秋栽培では開花期間隔は夏栽培と同程度であったが, 花房数, 小花房数および小花房あたり花数が少ないことによって, 開花数が少なく, 開花期間が短くなった.

Reproductive effort and floral photosynthesis in Spiranthes cernua (Orchidaceae)

This study examined the cost of reproduction and photosynthetic characteristics of the reproductive structures of Spiranthes cernua, an agamospermic, terrestrial orchid. Reproduction was frequent: two-thirds of the plants flowered at least 2 yr in a row and one-fourth of the consecutive-year runs were ~3 yr. Neither a significant decrease in leaf area nor a reduced likelihood of flowering was observed following 1 or 2 yr of inflorescence production. While there was a tendency for plants producing >16 flowers to have decreased size the next year, plants with the greatest number of flowers (31+) were the most likely to reproduce. Leaf and reproductive gas exchange were measured in the field. Low but positive rates of net photosynthesis were documented at all stages of inflorescence development. The average rates of photosynthesis for each stage were: leaves, 9.2 mmol CO2/m2s; inflorescence in bud, 3.7 mmol CO2/m2s; inflorescence in flower, 2.5 mmol CO2/m2s and infructescence, 0.2 mmol CO2/m2s. Based on diurnal gas exchange, the contribution of leaves and reproductive structures to seasonal carbon assimilation was 91.6 and 8.4%, respectively. The role of the inflorescence as a source and sink for carbon assimilation may lower the cost of reproduction and support frequent inflorescence production.

Controlled-release Fertilizer Rate Influences Plant Growth, Flowering, and Tillering of Pennisetum alopecuroides

Information on fertility optimization for container-grown ornamental grasses is limited. For ornamental grasses, growers are concerned with the degree of flowering, number of tillers, and height and width of the plants as well as other growth or ornamental components. Pennisetum alopecuroides divisions potted into 8.5-L containers were grown outdoors in a container nursery from May through September. The potting medium used was a 3 aged pine bark: 2 peatmoss: 1 sand nursery mix (by volume), amended with dolomitic lime 3 kg/yard3. Sierra 17-6-10 plus minors, 8 to 9 month controlled-release fertilizer (CRF) was top dressed at 20, 30, 40, 50, or 60 g/container. Foliage height increased linearly with increasing CRF rate. Flower height increased to a maximum at 40 g of CRF per container and then decreased with higher levels of CRF. Basal plant width exhibited a quadratic response to CRF rate, reaching a maximum at 40 g of CRF per container. The greatest number of flowers and tillers were obtained using 50 g of CRF per container. Maximizing the number of flowers is important for marketing of Pennisetum, since this plant is grown primarily for its flowering.

Bumblebee visits to different colour morphs of the Washington lupine, <i>Lupinus polyphyllus</i>

We examined the flower visits of bumblebees (Hymenoptera, Apoidea, Bomb us spp.) to Lupinus polyphyllus Lindley (Fabaceae) in southern Finland. The racemes of the plant bear nectarless flowers which appear in three main colour morphs, blue, red and white, of which blue is the most common. Blue inflorescences had the greatest number of flowers and their proportion increased towards the end of the flowering period, whereas white flowers seemed to fade away more quickly and drop easier than those of the other morphs. Bumblebees seemed to prefer blue inflorescences over red and white in the beginning of the flowering period, but in the end of the period red and white inflorescences were visited more often than expected on the basis of their proportion in the field. Bumblebee species differed slightly in their colour preferences, for instance, B. lapidarius seldom visited white flowers. When the temperature was low and the wind was high, the visits to blue flowers were more numerous than expected, whereas in cloudy conditions red flowers were often visited. Bumblebees moved between the same coloured inflorescences more often than expected, because the colour selected in the beginning was favoured during the whole foraging trip and the nearest inflorescence having another colour was skipped. The pollinator behaviour favoured the existing proportions of colour morphs in the lupine populations.