Post-pollination mechanisms promoting outcrossing in a self-fertile conifer, Thuja plicata (Cupressaceae)

2005 ◽  
Vol 83 (3) ◽  
pp. 335-342 ◽  
Author(s):  
Lisa M O'Connell ◽  
Kermit Ritland
Keyword(s):  
Mating System ◽  
Seed Set ◽  
Seed Orchard ◽  
Thuja Plicata ◽  
Enzyme Electrophoresis ◽  
Embryo Abortion ◽  
Western Redcedar ◽  
Pollination Mechanisms ◽  
Number Of Seeds ◽  
Filled Seeds

In conifers, polyembryony (multiple embryos within an ovule) may decrease the number of seeds lost to random embryo abortion, and (or) increase the proportion of outcrossed seeds if outcrossed embryos out-compete selfed ones. Western redcedar (Thuja plicata Don ex D. Donn, Cupressaceae) is a conifer with a mixed (selfed and outcrossed) mating system and high self-fertility with simple (archegonial) polyembryony. To test whether polyembryony can decrease seed abortion or the proportion of selfed seedlings, we conducted controlled pollinations in a seed orchard in southwestern British Columbia. Four trees received a total of 48 pollination treatments consisting of self, outcross, or mixtures of self and outcross pollen. Enzyme electrophoresis identified selfed seeds in the mixed pollen treatments. Reduction in the proportion of filled seeds (seed set) owing to selfing was approximately 30% for three of the trees and 93% for the fourth. Following mixed pollinations we did not observe an increase in seed set attributable to polyembryony. However, when trees received high ratios of self-pollen they produced fewer selfed seedlings than expected, suggesting embryo competition. The consequences of these results on the mating system of western redcedar are discussed.Key words: conifer, Cupressaceae, embryonic lethals, inbreeding depression, polyembryony, Thuja plicata.

The mating system in natural populations of western redcedar (Thuja plicata)

2001 ◽  
Vol 79 (6) ◽  
pp. 753-756 ◽  
Author(s):  
Lisa M O'Connell ◽  
Frédérique Viard ◽  
John Russell ◽  
Kermit Ritland
Keyword(s):  
British Columbia ◽  
Mating System ◽  
Natural Populations ◽  
Seed Orchard ◽  
Outcrossing Rate ◽  
Thuja Plicata ◽  
Western Redcedar ◽  
Outcrossing Rates ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Thuja Plicata Donn

Outcrossing rates and the correlation of paternity were estimated in six natural populations of western redcedar (Thuja plicata Donn. ex D. Don) in southwestern British Columbia. Over 3000 offspring were assayed, as progeny arrays, for the only sufficiently polymorphic isozyme locus in this species, glucose-6-phosphate dehydrogenase. Estimates of population outcrossing rates ranged from 0.173 to 1.257 and averaged 0.715 ± 0.045 (mean ± SD). Estimates of the correlation of paternity generally did not differ from zero. Six of the seven outcrossing estimates (one population was surveyed in two consecutive years) were higher than a previous seed orchard study. However, these outcrossing rates are still lower than those estimated for most other species of conifers. Population outcrossing rates also showed wide variation, and this variation is discussed in terms of ecological and phenological differences among populations.Key words: Cupressaceae, conifers, isozymes, outcrossing rate, inbreeding.

Seasonal changes in seed reduction in lodgepole pine cones caused by feeding of Leptoglossus occidentalis (Hemiptera: Coreidae)

2006 ◽  
Vol 138 (6) ◽  
pp. 888-896 ◽  
Author(s):  
Ward B. Strong
Keyword(s):  
Adult Female ◽  
Pinus Contorta ◽  
Seed Set ◽  
Lodgepole Pine ◽  
Seed Orchard ◽  
Damage Potential ◽  
Leptoglossus Occidentalis ◽  
Pine Cones ◽  
Insect Exclusion ◽  
Filled Seeds

AbstractManagement of Leptoglossus occidentalis Heidemann in lodgepole pine (Pinus contorta var. latifolia Engelm.) seed orchards of British Columbia, Canada, would be improved with knowledge of its damage potential at different times of the growing season. Mesh insect-exclusion bags were placed over cones, and adults or nymphs of L. occidentalis were enclosed in different bags for 9 periods of 10 to 38 days between 6 May and 17 September 2004. Feeding by adult females between 6 May and 28 May reduced total extractable seeds, a result of ovule damage before fertilization. Reduction in the number of filled seeds per cone was highest between 6 May and 29 June, with each adult female reducing yield by approximately 1.7 seeds per day. Between 29 June and 10 August, each adult female reduced the number of filled seeds per cone (seed set) by 1.0 to 1.25 per day. Seed set reduction declined to approximately 0.25 filled seeds per adult female per day after 10 August. Third to fifth instars caused seed set reduction between 0.6 and 1.2 filled seeds per cone per nymph feeding day from 29 June to 10 August. Utilizing these findings would improve management of L. occidentalis in a commercial seed orchard setting.

The mating system in natural populations of western redcedar (Thuja plicata)

2001 ◽  
Vol 79 (6) ◽  
pp. 753-756 ◽  
Author(s):  
Lisa M. O'Connell ◽  
Frédérique Viard ◽  
John Russell ◽  
Kermit Ritland
Keyword(s):  
Mating System ◽  
Natural Populations ◽  
Thuja Plicata ◽  
Western Redcedar

Selfing and correlated paternity in relation to pollen management in western red cedar seed orchards

Botany ◽  
2020 ◽  
Vol 98 (7) ◽  
pp. 353-359
Author(s):  
Kermit Ritland ◽  
Allyson Miscampbell ◽  
Annette Van Niejenhuis ◽  
Patti Brown ◽  
John Russell
Keyword(s):  
Mating System ◽  
Seed Orchard ◽  
Paternity Analysis ◽  
Thuja Plicata ◽  
Red Cedar ◽  
Management Schemes ◽  
Unbiased Estimates ◽  
Western Red Cedar ◽  
New Feature ◽  
Thuja Plicata Donn

We used microsatellite genetic markers to evaluate the mating system of western red cedar (Thuja plicata Donn ex D. Don) under various seed orchard pollen management schemes. We primarily examined whether supplemental mass pollination (SMP) can reduce the observed selfing rates. Pollen blowing and “hooding” were also examined in smaller tests. Only SMP was consistently effective in reducing the selfing rate, from 30% to 20%. The correlation of paternity was quite high (60%–90%) in two of three orchards, and in these two orchards the application of SMP reduced this correlation by about 10% as well. The correlation of paternity is the fraction of full-sibling vs. half-sibling progeny, and unbiased estimates can be obtained with few loci, even single loci, in contrast to other types of paternity analysis. We also find the microsatellite amplicon sizes should be pooled into “bins” of 2–4 nucleotides, owing to unintended errors of assay; otherwise the estimates are biased. This new feature of mating system estimation was incorporated into the computer program MLTR.

scholarly journals Effect of Foliar-Applied Gibberellin A3 on Male and Female Strobilus Production and Cone and Seed Quality in Western Redcedar (Thuja plicata Donn)

2007 ◽  
Vol 22 (4) ◽  
pp. 297-306
Author(s):  
J.H. Russell ◽  
O. Hak
Keyword(s):  
Seed Quality ◽  
Foliar Application ◽  
Seed Orchard ◽  
Shoot Elongation ◽  
Thuja Plicata ◽  
Western Redcedar ◽  
Male And Female ◽  
Cone Production ◽  
Gibberellin A3 ◽  
Thuja Plicata Donn

Abstract Western redcedar (Thuja plicata Donn) foliar-applied gibberellin A3 (GA3) induction trials were performed over a 4-year period at a number of different seed orchards in coastal British Columbia. The effects of GA3 timing, concentration, and frequency on male and female strobilus production, as well as timing on seed quality, were studied. Male and female strobili were induced over the complete span of shoot elongation from May to August, indicative of a less-precise induction period than species in the Pinaceae family. Female strobilus production was correlated with shoot increment, such that maximum cone production was associated with maximum shoot elongation. In addition, seed quality decreased with decreasing shoot increments in August. For operational efficiency, a one-time foliar application of 200 mg/l GA3 is sufficient for adequate female strobilus production. To increase the female-to-male strobilus ratio, a two-time foliar application of GA3 mid-May and mid-July, concentrating on vigorous shoots, is recommended. Results are discussed in relation to seed orchard management techniques that may potentially influence selfing rates.

Variation in seed set and proportions of outcrossed progeny with clones, crown position, and top pruning in a Douglas-fir seed orchard

1986 ◽  
Vol 16 (3) ◽  
pp. 502-507 ◽  
Author(s):  
S. K. Omi ◽  
W. T. Adams
Keyword(s):  
Maximum Likelihood ◽  
Seed Set ◽  
Seed Orchard ◽  
Douglas Fir ◽  
Crown Position ◽  
Maximum Likelihood Procedure ◽  
Clonal Variability ◽  
Allozyme Loci ◽  
Filled Seeds

The effects of clonal variability, crown position of cones, and top pruning on the proportions of viable outcrossed progeny [Formula: see text] and filled seeds (PF) were investigated in a 20-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seed orchard. Estimates of [Formula: see text] were derived by means of a maximum likelihood procedure from data from 10 allozyme loci. Values for [Formula: see text] and PF were significantly heterogeneous (P < 0.05) among six selected clones for all pruning treatment x clone combinations. On the average, estimated values for [Formula: see text] and [Formula: see text] were greater in seeds collected from the upper crown [Formula: see text] than from the lower crown [Formula: see text]. Combined over crown positions, pruning appeared to have little effect on [Formula: see text], although the proportion of filled seeds was slightly lower in pruned ramets [Formula: see text] than in unpruned ramets [Formula: see text]. The overall frequency of viable selfs [Formula: see text] in the progeny of the six clones was 0.08.

scholarly journals Influence of bee pollination on quality and quantity of onion (Allium cepa L.) seed

2020 ◽  
Vol 13 (2) ◽  
pp. 200-204
Author(s):  
Subhash B. Kandakoor ◽  
Jitendra Kumar S. Hilli
Keyword(s):  
Allium Cepa ◽  
Seed Weight ◽  
Seed Set ◽  
Maximum Activity ◽  
Major Contributor ◽  
Flowering Stage ◽  
Bee Pollination ◽  
Allium Cepa L ◽  
Bee Colonies ◽  
Number Of Seeds

The activity of bees pollination in onion was observed throughout the day. Numerically maximum activity was observed during afternoon hours (12.00 to 2.00 PM) with 7.00 numbers in rock bee, 5.40 in Indian bees, 11.60 in little bees and 7.80 in case of dammer be, respectively. Among the four species of bees, little bees were more in entire day with highest of 111.60 bees/10 inflorescence/ minute followed by dammer bee with 9.40 bees/10 inflorescence/ minute, Among the bees major contributor was little bee, this may be due to more colonies of little bees in that area and destruction of rock bee colonies. Also, the bee acitivty was observed maximum number at 100 per cent flowering stage. The observations on number of seeds per umbel, 1000 seed weight and per cent germination under the laboratory conditions. The results clearly indicated that, maximum number of seeds per umbel was observed in open pollinated flowers with 339.30 ± 60.27 seeds per umber where all the four species of bees were made visits regularly followed by in case of pollination in mesh cloth cage with bees with 330.00±35.80 and very least number of seed set was observed in case of pollination in mesh cloth cage without bees with only 60.70 seeds/umbel. Similarly, 1000 seed weight also differed significantly in case of pollination with bees and without bees. In case of with bees it weighed around 3.37 g/1000 seeds followed by 3.10 g/1000 seeds in onion with bee cage and least in case of control with only 1.97 g/1000 seeds.

Mating system and cross-compatibility of races of Epacris impressa

1982 ◽  
Vol 30 (2) ◽  
pp. 131 ◽  
Author(s):  
YJ Fripp
Keyword(s):  
Mating System ◽  
Hybrid Seed ◽  
Self Incompatibility ◽  
Low Level ◽  
Cross Compatibility ◽  
Outcrossing Species ◽  
Different Populations ◽  
Number Of Seeds

The mating system and cross-compatibility of races of Epacris impressa Labill. were examined by a series of selfings, outcrosses between plants of the same race from the same and different populations, and outcrosses between plants of different races. The percentage of pollinations which gave capsules and the number of seeds present per capsule for these four types of crosses, and whether the seeds germinated, were scored. The results indicate that E. impressa is an outcrossing species with a self-incompatibility mechanism to keep selfing at a low level, the races cross freely and the hybrid seed is viable. The means over all races for the above four types of crosses were 8.7 (selfing), 62.3, 62.5 and 65.5 for the percentage of pollinations that were successful and 8.4 (selfing), 43.5, 41.2 and 39.0 for the number of seeds per capsule. The results of a limited number of crosses between Epacris impressa and other epacrid species are also given.

Sexual reproduction in western red cedar (Thuja plicata)

1980 ◽  
Vol 58 (12) ◽  
pp. 1376-1393 ◽  
Author(s):  
John N. Owens ◽  
M. Molder
Keyword(s):  
Sexual Reproduction ◽  
Seed Production ◽  
Low Temperatures ◽  
Female Gametophyte ◽  
Seed Set ◽  
Thuja Plicata ◽  
Insect Damage ◽  
Red Cedar ◽  
Pollination Drop ◽  
Micropylar Canal

Pollen cones and seed cones ended dormancy in mid-February, microsporogenesis occurred in late February, and pollination occurred for about 1 week in early March. Pollen was shed at the two-celled stage. Pollination drops were exuded from only a few ovules at one time. Pollen contacting the pollination drop was rapidly taken in. The pollination drop was withdrawn into the micropyle which was later sealed by enlargement of cells lining the micropylar canal. Megasporogenesis occurred in late February but female gametophytes did not mature and fertilization did not occur until late May. An archegonial complex formed containing seven to nine archegonia, of which several usually were fertilized. Proembryo development varied depending upon the size and shape of the archegonia. Usually, a 12-celled, three-tiered proembryo formed by mid-June. Cleavage polyembryony was not observed. Embryos were mature by mid-August and most seed was shed in September and October.The potential seed set was only 16 seeds per cone and filled seed averaged only 2.6 per cone. Most potential seed was lost because of early ovule abortion from unknown causes, insect damage, or low temperatures at or shortly after pollination. Some potential seeds were lost because the ovules were not pollinated or the embryos aborted. These seeds were soft but nearly normal appearing and contained spongy female gametophyte tissue. Methods of maximizing seed production are suggested.

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