Pollination mechanism of seed orchard interior spruce

1995 ◽  
Vol 25 (9) ◽  
pp. 1434-1444 ◽  
Author(s):  
C. John Runions ◽  
Glenda L. Catalano ◽  
John N. Owens
Keyword(s):  
Temporal Correlation ◽  
Seed Orchard ◽  
Pollination Mechanism ◽  
Pollination Success ◽  
Engelmann Spruce ◽  
Interior Spruce ◽  
Pollination Drop ◽  
Cone Development ◽  
Dry Conditions ◽  
Natural Range

The pollination mechanism of interior spruce (white spruce, Piceaglauca (Moench) Voss, or Engelmann spruce, Piceaengelmannii Parry, and their hybrid) trees growing in a seed orchard was studied. Seed orchards are established in areas that are warmer and drier than the parent tree natural range. Hot, dry conditions during the pollination period adversely affected secretion of the pollination drop in unbagged seed cones as compared with bagged cones on the same tree. Unbagged cones remained open and apparently receptive for pollination for 5.3 ± 1.6 days (100 ± 31 h at >10°C), but pollination drops did not appear during this period. Pollination drops were secreted as cones began to close. The temporal correlation observed between cone closure and pollination drop secretion occurred as well in the higher relative humidity environment within pollination bags. Pollination drops in unbagged cones were smaller and did not persist as long as those in bagged cones. The micropylar arms, which capture pollen prior to pollination drop secretion, withered completely in unbagged cones before pollination drops were observed. Some withering of micropylar arms during cone receptivity is natural but complete withering means that the arms can not function in pollen capture throughout the period during which cones remain open. For this reason, supplemental mass pollination is best carried out early during the receptive period for trees growing in hot, dry environments. Overhead misting, used periodically during the receptive period to cool orchard trees, might slow seed-cone development and reduce micropylar arm withering, thereby increasing pollination success after supplemental mass pollination.

Pollen scavenging and rain involvement in the pollination mechanism of interior spruce

1996 ◽  
Vol 74 (1) ◽  
pp. 115-124 ◽  
Author(s):  
C. John Runions ◽  
John N. Owens
Keyword(s):  
Picea Glauca ◽  
Selective Pressure ◽  
Seed Orchard ◽  
Picea Engelmannii ◽  
Pollination Efficiency ◽  
Pollination Mechanism ◽  
Pollination Mechanisms ◽  
Seed Cone ◽  
Interior Spruce ◽  
Pollination Drop

Pollination drops are secreted from the ovules of interior spruce (Picea glauca or Picea engelmannii and their hybrid) as seed cones begin to close at the end of the pollination period. Secreted pollination drops persist within spaces surrounding the micropylar opening in closed seed cones. Saccate pollen floats into the micropyle within the pollination drop. Pollination drops become voluminous enough, within the enclosed spaces, to scavenge pollen adhering to the micropylar arms and other surfaces in proximity with the micropyle. Scavenging of pollen from cone surfaces adjacent to the integuments is sometimes facilitated by rainwater that can float pollen into the opening of the micropyle before cone closure and pollination drop secretion. In practice, periodic, light misting of seed orchard trees during seed cone receptivity might increase pollination efficiency by mimicking rainwater involvement in the pollination mechanism. Rainwater involvement in pollination of some modern conifers may reflect a similar situation in the pollination mechanisms of ancestral conifers. Environments with limited rainfall combined with the requirement for moisture in the pollination mechanism may have provided the selective pressure for evolution of the pollination drop. Keywords: pollination drop, Picea, conifer, sacci.

How the pollination mechanism and prezygotic and postzygotic events affect seed production in Larixoccidentalis

1994 ◽  
Vol 24 (5) ◽  
pp. 917-927 ◽  
Author(s):  
John N. Owens ◽  
Sheila J. Morris ◽  
Glenda L. Catalano
Keyword(s):  
Seed Production ◽  
Ultrastructural Changes ◽  
Optimal Time ◽  
Cell Cytoplasm ◽  
Pollination Mechanism ◽  
X Ray ◽  
Pollination Success ◽  
Pollen Hydration ◽  
Pollination Drop ◽  
Supplemental Pollination

The pollination mechanism of western larch (Larixoccidentalis Nutt.) is described in relation to the optimal time of pollination. Five stages of conelet receptivity were recognized and stages two to four had the greatest pollination success. Four categories of seed were recognized by X-ray and dissection of seeds from mature cones. The causes of degenerated, empty, and rudimentary seeds are discussed and recommendations are made for increased seed production through supplemental pollination. Light microscope and ultrastructural observations were made of the pollination mechanism and of pollen from 0 to 72 h after pollination, during pollen engulfment, during shedding of the exine, and during penetration of the nucellus. Pollen attachment to stigmatic hairs and pollen engulfment are described. Pollen hydration and ultrastructural changes began about 72 h after pollination. The exine was shed but the pollen remained just inside the sealed micropyle for 5–6 weeks. A pollination drop secreted from the nucellus then carried the pollen to the nucellus. There a pollen tube formed and penetrated the nucellus. Two male nuclei formed in a common body-cell cytoplasm when the pollen tubes reached the archegonia.

The pollination mechanism of Engelmann spruce (Picea engelmannii)

1987 ◽  
Vol 65 (7) ◽  
pp. 1439-1450 ◽  
Author(s):  
John N. Owens ◽  
Sheila J. Simpson ◽  
Guy E. Caron
Keyword(s):  
Seed Set ◽  
Picea Engelmannii ◽  
Diurnal Fluctuation ◽  
Secretory Cells ◽  
Controlled Environment ◽  
High Humidity ◽  
Natural Conditions ◽  
Pollination Mechanism ◽  
Engelmann Spruce ◽  
Pollination Drop

The pollination mechanism of Picea engelmannii (Parry) was studied on small potted scions under natural conditions and in controlled environment chambers. Six stages of conelet development were recognized and related to pollen receptivity. Cone-lets appeared receptive for about 2 weeks but were actually receptive for only about 1 week. Secretory droplets appearing on the micropylar arms collected pollen for several days before pollination drops formed. Pollination drops formed acropetally in the conelet and only once from each ovule. Pollination caused rapid recession of the pollination drop, whereas the drop remained for several days on unpollinated ovules. There was some decrease in size of pollination drops during midday and reemergence the following night. Pollination drops were secreted by the nucellar tip in a manner similar to nectaries. Secretory cells collapsed following secretion. The drop contained 4.3% glucose and 3.8% fructose but no sucrose. High humidity increased the longevity and decreased the diurnal fluctuation in size of pollination drops. Conelets from trees with low leaf water potential developed more slowly and produced smaller and more viscous pollination drops. Cones averaged 103 ovuliferous scales, 90% of which were fertile. However, usually less than 50% of the potential seed set was achieved. One of the major causes for low seed set is inadequate pollination. A better understanding of the pollination mechanism and the receptive period may improve seed efficiency in controlled and supplemental mass pollinations.

Frost hardiness, height, and dormancy of 15 short-day, nursery-treated interior spruce seed lots

2000 ◽  
Vol 30 (7) ◽  
pp. 1096-1105 ◽  
Author(s):  
C DB Hawkins ◽  
K B Shewan
Keyword(s):  
Picea Glauca ◽  
Day Treatment ◽  
Field Performance ◽  
Seed Orchard ◽  
Frost Hardiness ◽  
Control Treatment ◽  
Short Day ◽  
Physiological Processes ◽  
Interior Spruce ◽  
Day Nursery

Fifteen seed lots, five each from natural-stand, seed-orchard, and full-sib collections, of interior spruce (Picea glauca (Moench) Voss, Picea engelmannii Parry ex Engelm., and their naturally occurring hybrids) were sown in February 1993. One half of each seed lot received an ambient photoperiod (control) treatment, while the other half got a blackout (short-day) treatment. All seedlings were grown under ambient photoperiod except during the 17 days of blackout. Frost hardiness assessments were done between July and May. Blackout treatment was effective in regulating height and promoting frost hardiness in all seed lots, particularly vigorous ones. Seed lots originating from high latitude or elevation were more frost hardy both at fall lift and spring planting. Full-sib seed lots from similar latitude displayed no elevational frost-hardiness trend. Blackout treatment promoted seedling dormancy (estimated with days to bud break) at lift, but it had little or no effect on dormancy at planting. Seedling dormancy and frost hardiness were acquired and lost differently, suggesting that they are independent physiological processes. Blackout treatment significantly reduced new roots at planting in all lots. This could retard early field performance and negate the apparent utility of blackout treatment.

Simulated conversion of unmanaged interior spruce-subalpine fir stands to a regulated uneven-aged structure

2000 ◽  
Vol 76 (3) ◽  
pp. 465-474 ◽  
Author(s):  
Craig Farnden
Keyword(s):  
Old Growth ◽  
Individual Tree ◽  
Subalpine Fir ◽  
High Q ◽  
Engelmann Spruce ◽  
Management Objectives ◽  
Individual Tree Growth ◽  
Interior Spruce ◽  
Growth Attributes ◽  
Tree Growth Model

A localized version of the Forest Vegetation Simulator (FVS) individual tree growth model was developed to simulate stand level impacts under a variety of uneven-aged management regimes in old-growth interior spruce-subalpine fir forests near Prince George British Columbia. Options for using uneven-aged management to satisfy a range of management objectives were simulated using different sets of BDq regulation parameters, and by varying species composition and rules for reserve trees. The greatest timber yields were attained by promoting the highest possible spruce component, using high q ratios, low to moderate maximum diameters and 20 to 25 year cutting cycles, and allowing no reserves. Using strategies to promote stand structures maintaining some old-growth attributes resulted in much lower timber yields. Key words: white spruce, Engelmann spruce, subalpine fir, uneven-aged management, BDq regulation, simulated yield

The pollination mechanism and development after bud burst of cones of Larix laricina

1991 ◽  
Vol 69 (6) ◽  
pp. 1179-1187 ◽  
Author(s):  
G. R. Powell ◽  
Kathleen J. Tosh
Keyword(s):  
Key Words ◽  
Seed Size ◽  
Larix Laricina ◽  
Bud Burst ◽  
Scale Growth ◽  
Pollination Mechanism ◽  
Seed Cone ◽  
Cone Development ◽  
Micropylar Canal ◽  
Pollen Cone

Pollen-cone and seed-cone development, from bud burst to maturity, was investigated on Larix laricina (Du Roi) K. Koch in three young plantations. The pollination mechanism was emphasized. Pollen cones grew rapidly to shed pollen, shrivelled, and remained on the trees for a year or more. Pollen was directed to the ovular regions by the bracts of the seed cones. Pollen adhered among papillae on the larger of two integument extensions. Degeneration of the centre of the papillate integument tip caused a collapse that drew pollen in as the papillate rim grew inward. This ingrowth was joined by that of the smaller integument extension, resulting in a sealed tubular structure that enclosed a dry micropylar canal. Pollen was held by the ingrown plug of degenerated tissue as the nucellus tip expanded into the base of the canal. As this occurred, the ovules, with or without pollination, grew to ultimate seed size, and the initially small ovuliferous scales overgrew the bracts. First bract, then ovuliferous-scale growth was associated with a double-sigmoid form of cone elongation. In mature cones the bracts decreased and the ovuliferous scales (except near the tip) increased in size acropetally. Key words: bract, integument, ovuliferous scale, pollen cone, seed cone, tamarack or eastern larch.

The importance of fruit set, fruit abortion, and pollination success in fruit production of teak (Tectona grandis)

2010 ◽  
Vol 40 (11) ◽  
pp. 2204-2214 ◽  
Author(s):  
E. R. Palupi ◽  
J. N. Owens ◽  
S. Sadjad ◽  
Sudarsono ◽  
D. D. Solihin
Keyword(s):  
Fruit Set ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Tectona Grandis ◽  
Seed Orchard ◽  
Fruit Production ◽  
Time Of Day ◽  
Natural Forests ◽  
Pollination Success ◽  
Fruit Abortion

Teak ( Tectona grandis L.) is believed to have been introduced from India 400–500 years ago and there appear to be no old-growth natural forests. However, Indonesia has many teak plantation forests and 40%–50% of seeds for reforestation come from seed orchards and the remainder from plantations. In both, flower and fruit abortion results in low fruit set and thus seed production. We investigated flower and fruit development in a clonal seed orchard in East Java in 1999 and 2001 using cross- and open-pollinated trees. The rates of abortion using cross-pollinations showed a similar pattern but were lower than for open-pollinations. The highest rate of abortion in cross- and open-pollinations was during pollination and fertilization, ranging 11%–23% and 31%–32%/day, respectively, less during fruit initiation (5%–6% and 6%–8%/day) and the lowest was during fruit maturation (<0.5%/day). Cross-pollinations increased fruit production by 10-fold compared with open-pollinations. About 30% of flowers were pollinated with an average of five pollen grains per stigma in open-pollinations. Pollen viability varied among clones and time of day but was not affected by position of flowers in an inflorescence. We conclude that low pollination success and low pollen viability are major causes for low fruit production in teak and are related to insect pollinators.

Postdormancy seed-cone development and the pollination mechanism in western hemlock (Tsugaheterophylla)

1989 ◽  
Vol 19 (1) ◽  
pp. 44-53 ◽  
Author(s):  
Anna M. Colangeli ◽  
John N. Owens
Keyword(s):  
Pollen Grains ◽  
Pollen Tubes ◽  
Epicuticular Wax ◽  
Western Hemlock ◽  
Bud Burst ◽  
Pollination Mechanism ◽  
Seed Cone ◽  
Cone Development ◽  
And Function

The development and function of the pollination mechanism is described for hemlock (Tsugaheterophylla (Raf.) Sarg.). Controlled pollinations at various stages following bud burst were used to define the period of maximum receptivity. Western hemlock has a pollination mechanism unlike that observed in other native conifers. The pollen grains were not taken into the micropyles; instead, the roughly sculptured pollen grains adhered to the long epicuticular wax covering the bracts. Seed cones became receptive to pollen soon after the bracts emerged from the bud scales and remained receptive until shortly before cone closure. Several days after the cones fully emerged beyond the bud scales, the ovuliferous scales elongated over the bracts, trapping the pollen between the bracts and scales. Several weeks after pollination, pollen germinated on the bracts and formed long pollen tubes which grew towards and into the micropyles.

Clonal-row versus random seed orchard designs: interior spruce mating system evaluation

2007 ◽  
Vol 37 (3) ◽  
pp. 690-696 ◽  
Author(s):  
Y.A. El-Kassaby ◽  
M.U. Stoehr ◽  
D. Reid ◽  
C.G. Walsh ◽  
T.E. Lee
Keyword(s):  
Mating System ◽  
Minor Component ◽  
Slight Modification ◽  
Seed Orchard ◽  
Outcrossing Rate ◽  
Genetic Quality ◽  
Seed Orchards ◽  
Interior Spruce ◽  
Seed Crops ◽  
A Minor

Mating system pattern (selfing or outcrossing and correlated matings levels) comparisons between two interior spruce seed orchard designs (clonal-row and random) managed under intensive crown and pollen management were conducted. Crown manipulation consisted of tree topping and branch pruning, while pollen management involved multiple supplemental mass-pollination applications during peak seed-cone reproductive receptivity and pollen agitation using helicopters. Significant differences between orchards’ multilocus outcrossing rate estimates were observed, and both estimates significantly departed from complete outcrossing (t = 1.0). Clonal arrangements in the clonal-row design permitted higher chances for selfing (t = 0.948) in comparison with those of the random design (t = 0.989). Intensive pollen management, while effective, still produced a minor component of selfing. Both orchard designs produced similar individual tree's outcrossing rate trends with the majority showing high outcrossing, while few individuals showed high selfing propensity. Estimates of correlated mating varied substantially between the two seed orchard designs with 9.3% and 4.3% for the clonal-row and random seed orchards, respectively. While small but significant differences in the genetic quality of the seed crops were observed between the two orchard designs, the establishment of clonal-row seed orchards should be given serious considerations specifically under committed pollen and crown management. The ease of crop and orchard management in the clonal-row design outweighs the observed differences in the seed crop genetic quality. A slight modification to the clonal-row design is proposed and is expected to reduce the observed minor genetic quality differences between the two orchard designs.

Pollen morphology and development of the pollination mechanism in Tsuga heterophylla and T. mertensiana

1983 ◽  
Vol 61 (12) ◽  
pp. 3041-3048 ◽  
Author(s):  
John N. Owens ◽  
Margaret Dianne Blake
Keyword(s):  
Reproductive Biology ◽  
Pollen Morphology ◽  
Pollen Tubes ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Pollination Mechanism ◽  
Pollination Drop ◽  
Tsuga Mertensiana

Pollen of Tsuga heterophylla (Raf.) Sarg. (western hemlock) is nonsaccate and bears spines, whereas pollen of Tsuga mertensiana (Bong.) Carr. (mountain hemlock) is saccate and lacks spines. The pollination mechanism in western hemlock consists of a short funnel-like integument tip with a large micropyle. Pollen may enter the micropyle or germinate on the bract or ovuliferous scale and form long pollen tubes. The pollination mechanism in mountain hemlock consists of two large micropylar flaps which secrete minute droplets to which pollen adheres. A pollination drop is not formed in either species. These features are discussed in relation to the taxonomy of the genus and the reproductive biology of these two species.

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