The reproductive biology of boreal forest herbs. II. Phenology of flowering and fruiting

1987 ◽  
Vol 65 (10) ◽  
pp. 2047-2056 ◽  
Author(s):  
Kaius Helenurm ◽  
Spencer C. H. Barrett
Keyword(s):  
Boreal Forest ◽  
Fruit Set ◽  
Pollen Limitation ◽  
Fruit Production ◽  
Fruit Removal ◽  
Cornus Canadensis ◽  
Forest Herbs ◽  
Pollinator Service ◽  
Maianthemum Canadense ◽  
Major Factors

The flowering and fruiting phenologies of 12 boreal forest herbs were recorded during 1979 (flowering and fruiting) and 1980 (flowering only) in spruce–fir forests of central New Brunswick. The species studied were Aralia nudicaulis, Chimaphila umbellata, Clintonia borealis, Cornus canadensis, Cypripedium acaule, Linnaea borealis, Maianthemum canadense, Medeola virginiana, Oxalis montana, Pyrola secunda, Trientalis borealis, and Trillium undulatum. Flowering in the community occurred from mid-May to the end of July. The order of flowering was maintained in the 2 years, but the degree of synchronization of inflorescences differed in several species. Fruiting in the community began in mid-July and extended beyond the end of September. The percentage of buds that ultimately bore fruit ranged from 0 (Cypripedium acaule) to 61% (Aralia nudicaulis). With the exception of Cypripedium acaule, which received little pollinator service, the self-incompatible species, Cornus canadensis, Maianthemum canadense, and Medeola virginiana, experienced the lowest levels of fruit-set. Pollen limitation and predation of developing fruit appear to be the major factors limiting percentage fruit-set in boreal forest herbs. Fruit production varied with time of flowering of inflorescences in several species, with periods of low fruit-set tending to coincide with lower densities of flowering inflorescences. Significant rates of fruit removal by herbivores occurred in all sarocochorous species. Disappearance of fruits from infructescences ranged from 31 (Medeola virginiana) to 95% (Aralia nudicaulis), with highest removal rates occurring during periods of greatest fruit availability.

The reproductive biology of boreal forest herbs. I. Breeding systems and pollination

1987 ◽  
Vol 65 (10) ◽  
pp. 2036-2046 ◽  
Author(s):  
Spencer C. H. Barrett ◽  
Kaius Helenurm
Keyword(s):  
Boreal Forest ◽  
Reproductive Biology ◽  
Fruit Set ◽  
Experimental Studies ◽  
Reproductive Mode ◽  
Breeding Systems ◽  
Cornus Canadensis ◽  
Forest Herbs ◽  
Maianthemum Canadense ◽  
Floral Syndromes

Detailed observations and experimental studies of the reproductive biology of 12 boreal forest herbs were conducted over a 3-year period (1978–1980) in spruce–fir forests of central New Brunswick. The species examined were Aralia nudicaulis, Chimaphila umbellata, Clintonia borealis, Cornus canadensis, Cypripedium acaule, Linnaea borealis, Maianthemum canadense, Medeola virginiana, Oxalis montana, Pyrola secunda, Trientalis borealis, and Trillium undulatum. All taxa are insectpollinated perennials and most exhibit clonal growth. Floral syndromes of the understory community are relatively unspecialized with many species possessing small white or green flowers. A total of 103 taxa of insects were collected from flowers during the 1979 season. Bombus spp. are the major pollinators of 5 of the 12 species. Syrphid flies, bee flies, and halictid and andrenid bees were also commonly observed. Controlled pollinations were undertaken to determine the breeding systems of herbs. Bagged, self-, cross- and open-pollinated treatments were used to investigate the capacity for self-pollination, compatibility status, and factors influencing fecundity in each species. A diversity of reproductive systems was revealed. Six species are completely dependent on insects for pollination, four species are weakly autogamous, one is strongly autogamous, and one appears to be apomictic. Comparisons of fruit-set and seed set from controlled self- and cross-pollinations indicate that four species are strongly self-compatible, one is dioecious, and the remainder display varying degrees of self-incompatibility. Despite this variation, outbreeding appears to be the most common reproductive mode. In several species there is evidence that low pollinator service limits fruit-set.

The neutralisation of acid rain by the leaves of four boreal forest species

1988 ◽  
Vol 66 (9) ◽  
pp. 1877-1882 ◽  
Author(s):  
B. A. Gaber ◽  
T. C. Hutchinson
Keyword(s):  
Boreal Forest ◽  
Acid Rain ◽  
Cell Walls ◽  
Leaf Surface ◽  
Weather Conditions ◽  
Cornus Canadensis ◽  
Exchange Processes ◽  
Rapid Changes ◽  
Maianthemum Canadense ◽  
Rate Of Evaporation

A field study was carried out in the boreal forest of Ontario to measure the neutralisation response of the leaves of Cornus canadensis, Aralia nudicaulis, Maianthemum canadense, and Acer spicatum to simulated acid rain. Plots of each species were sprayed with pH 5.6, 3.8, or 3.2 rain, and the pH of the raindrops on the leaves and on Parafilm (control) was measured with a microelectrode at 15-min intervals until the leaves dried. Species differed in their ability to neutralise the rain, with C. canadensis consistently neutralising acidic raindrops the most. The neutralisation response varied greatly between pH treatments, with greatest neutralisation occurring at the most acidic pH treatment. Raindrop neutralisation primarily took place within the first few minutes following the spray. For this reason, the dissolution of basic particulates on the leaf surface was probably responsible for the rapid changes in raindrop pH, while slower changes may reflect cation exchange processes with the cell walls. Weather conditions determined the rate of evaporation of the raindrops, and this affected their acidity. High rates of evaporation reduced the time available for leaf surface – raindrop interactions and are probably responsible for the acidification observed in some plots.

scholarly journals Spatial variability in pollen and resource limitation for fruit production of two species in interior Alaska: Vaccinium uliginosum and V. vitis-idaea

2019 ◽  
Author(s):  
Lindsey Viann Parkinson ◽  
Christa P.H. Mulder
Keyword(s):  
Soil Moisture ◽  
Boreal Forest ◽  
Resource Availability ◽  
Pollen Limitation ◽  
Canopy Cover ◽  
Fruit Production ◽  
Floral Resources ◽  
Soil Conditions ◽  
Vaccinium Uliginosum ◽  
Interior Alaska

AbstractMany recent studies assessing fruit productivity of plants in the boreal forest focus on interannual variability across a forested region, rather than on environmental variability within the forest. Frequency and severity of wildfires in the boreal forest affect soil moisture, canopy, and community structure at the landscape level, all of which may influence overall fruit production at a site directly (through resource availability) or indirectly (through impacts on pollinators). We evaluated how fruit production in two boreal shrubs, Vaccinium uliginosum (blueberry) and V. vitis-idaea (lingonberry), was explained by factors associated with resource availability (such as canopy cover and soil conditions) and pollen limitation (such as floral resources for pollinators and pollen deposition) across boreal forest sites of Interior Alaska. We classified our study sites into upland and lowland sites, which differed in elevation, soil moisture (lower in upland sites), and active layer (deeper in upland sites). We found that resource and pollen limitation differed between the two species and between uplands and lowlands. Lingonberry was more pollen limited than blueberry, and plants in lowland sites were more pollen limited relative to other sites while plants in upland sites were relatively more resource limited. Additionally, canopy cover had a significant negative effect in upland sites on a ramet’s investment in reproductive tissues and leaves versus structural growth, but little effect in lowland sites. These results point to importance of including pollinator abundance as well as resource availability in predictions for changes in berry abundance.

scholarly journals Selective Flower Removal Increases Cranberry Fruit Set

HortScience ◽  
1990 ◽  
Vol 25 (10) ◽  
pp. 1226-1228 ◽  
Author(s):  
Brian A. Birrenkott ◽  
Elden J. Stang
Keyword(s):  
Plant Development ◽  
Fruit Development ◽  
Fruit Set ◽  
Fruit Production ◽  
Vaccinium Macrocarpon ◽  
Insect Pollination ◽  
Fruit Removal ◽  
Hand Pollination ◽  
Production Area ◽  
Flower Thinning

Selective flower removal was used in 1987 and 1988 to evaluate intraplant competition or inhibition within flowering uprights of `Searles' cranberry (Vaccinium macrocarpon Ait.). The lowest two flowers were removed from uprights at various stages of plant development in 1987. With one or both of the two earliest, i.e., lowest, flowers developing `into fruit, 25% of the remaining flowers matured into fruit. Removal of the earliest two flowers at preblossom or late blossom resulted in ≈ 46% fruit set for the remaining flowers. Slightly fewer upper flowers set (36%) when the earliest flowers and fruit were removed at early fruit development. In 1988, the lowest two flowers were removed at preblossom and natural insect pollination was supplemented by hand pollination. Hand-pollinated (upper) flowers set 58% when the lowest two flowers were removed, compared to 17% for the unthinned control. Yield and fruit numbers were lowered slightly as a result of flower thinning in both years. A significant amount of variation in fruit production was explained by the number of flowering uprights per unit of production area in both years.

EFFECTS OF A SPLIT APPLICATION OF SEVIN-4-OIL® ON POLLINATORS AND FRUIT SET IN A SPRUCE–FIR FOREST

1984 ◽  
Vol 116 (3) ◽  
pp. 457-464
Author(s):  
Richard W. Hansen ◽  
Eben A. Osgood
Keyword(s):  
Fruit Set ◽  
Spruce Budworm ◽  
Split Application ◽  
Cornus Canadensis ◽  
Native Bee ◽  
Maianthemum Canadense ◽  
Pollinator Populations

AbstractCounts of four pollinating insect groups were taken in unsprayed forest localities and in areas sprayed with a split application of Sevin-4-oil® (carbaryl) for spruce budworm control. Results indicate a reduction of pollinator populations due to spraying.Fruit set, measured by fecundity ratios (fruits/flower), was determined for Cornus canadensis L., Maianthemum canadense Desf., Clintonia borealis (Ait.) Raf., and Viburnum cassinoides L. in sprayed and unsprayed areas. Fecundity values for C. canadensis and M. canadense were significantly lower in sprayed than in unsprayed areas. Fruit set of C. borealis was apparently unaffected by carbaryl spraying, but the seed/flower ratio was significantly reduced in the sprayed area. V. cassinoides fecundity values were unaffected by carbaryl application. Reductions in native bee populations probably had the greatest impact on fruit set.

Further assessment of pollen limitation in the waratah (Telopea speciosissima)

2000 ◽  
Vol 48 (2) ◽  
pp. 209 ◽  
Author(s):  
Ross L. Goldingay
Keyword(s):  
Vegetative Growth ◽  
Fruit Set ◽  
Pollen Limitation ◽  
Fruit Production ◽  
The Self ◽  
Original Experiment ◽  
Flower Production ◽  
Plant Groups ◽  
Fitness Consequences ◽  
Plant Families

The literature contains much debate about whether pollen limitation results in a cost to plants. A population of the waratah, Telopea speciosissima (Proteaceae), was found to be pollen limited in 1985. The present study examines the consequences and causes of this pollen limitation. In the 2–3 years following the original experiment, there was no difference in vegetative growth, flower production or fruit production between the hand-pollinated or control plants. There was no difference in inflorescence or fruit production between these two plant groups up to 9 years later. There was no cost of the experimental increase in reproduction. Experiments in 1988 failed to reveal further pollen limitation, suggesting that it may only occur in some years in this population. The retention of self-pollen on stigmas after anthesis was implicated as a cause of the original demonstration of pollen limitation because the waratah is self-incompatible, has highly synchronous flowering and, typical of the Proteaceae, deposits self-pollen on its stigmas at anthesis. These traits should provide a continuing influence on fruit set in all years. However, plants did not produce more fruits when the self-pollen was experimentally removed. This suggests that the waratah experiences pollen limitation in years when pollination and nutrient levels are not in equilibrium. Further studies of pollen limitation are required to fully understand the fitness consequences of this phenomenon, and to fully describe its frequency among different plant families and among plants with differing flowering strategies.

Chemical changes in simulated raindrops following contact with leaves of four boreal forest species

1988 ◽  
Vol 66 (12) ◽  
pp. 2445-2451 ◽  
Author(s):  
Brigitte A. Gaber ◽  
Thomas C. Hutchinson
Keyword(s):  
Boreal Forest ◽  
Dry Deposition ◽  
Ion Concentration ◽  
Forest Species ◽  
Ion Concentrations ◽  
Cornus Canadensis ◽  
Rapid Changes ◽  
Maianthemum Canadense ◽  
Forest Plant Species

Simulated raindrops of pH 5.6 or 3.2 were sprayed on four boreal forest plant species in situ, and raindrops were subsequently collected from their leaves for chemical analysis. The purpose was to understand better the changes involved in foliar neutralisation of acidic raindrops. The species used were Cornus canadensis, Aralia nudicaulis, Maianthemum canadense, and Acer spicatum. Samples were analysed for Ca2+, Mg2+, Na+, K+, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], Cl−, and F−, as well as pH. Changes in leaf raindrop ion concentrations were greater when sprayed with the pH 3.2 than with the pH 5.6 rain. Both increases and decreases in ion concentration were found, indicating leaching and (or) dissolution of particulates on the leaf or retention by the canopy, respectively. Rapid changes in ion concentrations suggest surface deposits play an important role in leaf raindrop neutralisation. Increases in [Ca2+] and [Mg2+] in raindrops with greater neutralisation are evidence that cation exchange may also be occurring (r2 = 0.170 and 0.321, respectively, at pH 3.2; p < 0.01). There were significant negative correlations between changes in [H+] and changes in[Formula: see text], [Formula: see text], and [Formula: see text] (r2 = 0.562, 0.525, and 0.297, respectively, at pH 3.2;p < 0.01). Most of the other ions measured also showed significant correlations with changes in [H+], but generally the correlation could account for only a small percentage of the observed results (low r2). Dry deposition was also measured.

scholarly journals Pollination and Breeding System of Lowbush Blueberries, Vaccinium angustifolium Ait. and V. myrtilloides Michx. (Ericacaeae), in the Boreal Forest

2005 ◽  
Vol 119 (1) ◽  
pp. 48 ◽  
Author(s):  
Masayuki Usui ◽  
Peter G. Kevan ◽  
Martyn Obbard
Keyword(s):  
Boreal Forest ◽  
Fruit Set ◽  
Frost Damage ◽  
Fruit Production ◽  
Breeding Systems ◽  
Vaccinium Angustifolium ◽  
Cross Pollination ◽  
Different Ages ◽  
Canadian Boreal Forest ◽  
Pollination Systems

Breeding systems and pollination requirements of two wild lowbush blueberries, Vaccinium angustifolium and V. myrtilloides, in the Canadian boreal forest in the Chapleau Crown Game Preserve, Ontario, were tested. Fruit production, size and seediness were significantly higher in samples exposed to natural pollination than in those cross- or self-pollinated by hand. There were no significant differences among artificial treatments (variously hand-pollinated and bagged) except when cross-pollination (xenogamy) was done by insect pins. In V. angustifolium, the density of flowering varied with forest age (canopy closure). It was most in open areas and least in the sites with the most mature forest. Although fruit-set and seediness varied among forest habitats of different ages, there were no significant differences between sites in forests of different ages. Thus, pollination seems to be similarly effective no matter the age of the forest. In both species, fruit-set in 1992, which had severe June frosts, was markedly poorer than that in 1993 when the flowers suffered little frost damage. The combined number of complete and incomplete seeds from the fruit among the breeding and pollination systems tested were similar; however, the ratio of complete seeds to total seeds was greater from cross-pollinated than from self-pollinated flowers. Our observations indicate that there is little natural fruit-set without insect-mediated cross-pollination and that cross-pollination provides much better fruit and seed-set than does self-pollination.

Reproductive Responses of Capsicum annuum to High Temperatures

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 543c-543
Author(s):  
Ami N. Erickson ◽  
Albert H. Markhart
Keyword(s):  
Capsicum Annuum ◽  
High Temperatures ◽  
Fruit Development ◽  
Flower Development ◽  
Fruit Set ◽  
Fruit Production ◽  
Yield Reduction ◽  
Bud Size ◽  
Growth Chambers ◽  
Constant Growth

Fruit yield reduction due to high temperatures has been widely observed in Solanaceous crops. Our past experiments have demonstrated that Capsicum annuum cultivars Ace and Bell Boy completely fail to produce fruit when grown at constant 33 °C. However, flowers are produced, continually. To determine which stages of flower development are sensitive to high temperatures, pepper buds, ranging in size from 1 mm to anthesis, were exposed to high temperatures for 6 hr, 48 hr, 5 days, or for the duration of the experiment. Fruit set for each bud size was determined. Exposure to high temperatures at anthesis and at the 2-mm size stage for 2 or more days significantly reduced fruit production. To determine whether inhibition of pollination, inhibition of fertilization, and/or injury to the female or male structures prevents fruit production at high temperatures, flowers from pepper cultivars Ace and Bell Boy were grown until flowers on the 8th or 9th node were 11 mm in length. Plants were divided between 25 °C and 33 °C constant growth chambers for 2 to 4 days until anthesis. At anthesis, flowers from both treatments were cross-pollinated in all combination, and crosses were equally divided between 33 or 25 °C growth chambers until fruit set or flowers abscised. All flower crosses resulted in 80% to 100% fruit set when post-pollination temperatures were 25 °C. However, post-pollination temperatures of 33 °C significantly reduced fruit production. Reduced fruit set by flowers exposed to high temperatures during anthesis and pollination is not a result of inviable pollen or ovule, but an inhibition of fertilization or initial fruit development.

Pollen limitation and xenia effects in a cultivated mass-flowering tree, Macadamia integrifolia (Proteaceae)

2021 ◽  
Author(s):  
Stephen J Trueman ◽  
Wiebke Kämper ◽  
Joel Nichols ◽  
Steven M Ogbourne ◽  
David Hawkes ◽  
...  
Keyword(s):  
Food Production ◽  
Fruit Set ◽  
Pollen Limitation ◽  
Pollination Services ◽  
Mass Flowering ◽  
Shell Mass ◽  
Cross Pollination ◽  
Macadamia Integrifolia ◽  
Kernel Yield ◽  
Flowering Tree

Abstract Background and Aims Pollen limitation is most prevalent among bee-pollinated plants, self-incompatible plants, and tropical plants. However, we have very little understanding of the extent to which pollen limitation affects fruit set in mass-flowering trees despite tree crops accounting for at least 600 million tons of the 9,200 million tons of annual global food production. Methods We determined the extent of pollen limitation in a bee-pollinated, partially self-incompatible, subtropical tree by hand cross-pollinating the majority of flowers on mass-flowering macadamia (Macadamia integrifolia) trees that produce about 200,000–400,000 flowers. We measured tree yield and kernel quality and estimated final fruit set. We genotyped individual kernels by MassARRAY to determine levels of outcrossing in orchards and assess paternity effects on nut quality. Key Results Macadamia trees were pollen limited. Supplementary cross-pollination increased nut-in-shell yield, kernel yield and fruit set by as much as 97%, 109% and 92%, respectively. The extent of pollen limitation depended upon the proximity of experimental trees to trees of another cultivar because macadamia trees were highly outcrossing. Between 84% and 100% of fruit arose from cross-pollination, even at 200 m (25 rows) from orchard blocks of another cultivar. Large variations in nut-in-shell mass, kernel mass, kernel recovery and kernel oil concentration were related to differences in fruit paternity, including between self-pollinated and cross-pollinated fruit, thus demonstrating pollen-parent effects on fruit quality, i.e. xenia. Conclusions This study is the first to demonstrate pollen limitation in a mass-flowering tree. Improved pollination led to increased kernel yield of 0.31–0.59 tons per hectare, which equates currently to higher farm-gate income of approximately US3,720–US7,080 per hectare. The heavy reliance of macadamia flowers on cross-pollination and the strong xenia effects on kernel mass demonstrate the high value that pollination services can provide to food production.

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