Factors affecting seed set in Douglas-fir (Pseudotsuga menziesii)

1991 ◽  
Vol 69 (2) ◽  
pp. 229-238 ◽  
Author(s):  
John N. Owens ◽  
Anna M. Colangeli ◽  
Sheila J. Morris
Keyword(s):  
Reproductive Success ◽  
Pseudotsuga Menziesii ◽  
Low Temperatures ◽  
Seed Set ◽  
Douglas Fir ◽  
Ovule Development ◽  
High Moisture ◽  
Embryo Abortion ◽  
Factors Affecting ◽  
Major Loss

Cone and seed development in Douglas-fir were studied from pollination until seed release in 1986. Cone abortion at, and shortly after, pollination was high, resulting from a combination of low temperatures and possibly high moisture and populations of microorganisms on cones. Seed potential averaged about 75 seeds per cone with 31 filled seed per cone, giving an average seed efficiency of 39%. The major loss of seed resulted from insufficient pollen in the ovules. Other causes were ovule and embryo abortion at various stages of development. The effects of prezygotic and postzygotic events on seed set are discussed with respect to the reproductive success of Douglas-fir. Key words: Douglas-fir, seed set, cone, ovule, development, abortion.

scholarly journals Seed parasitism redirects ovule development in Douglas fir

2005 ◽  
Vol 272 (1571) ◽  
pp. 1491-1496 ◽  
Author(s):  
Patrick von Aderkas ◽  
Gaëlle Rouault ◽  
Rebecca Wagner ◽  
René Rohr ◽  
Alain Roques
Keyword(s):  
Seed Development ◽  
Pseudotsuga Menziesii ◽  
Douglas Fir ◽  
Energy Reserve ◽  
Ovule Development ◽  
Parasitic Species ◽  
Seed Parasitism ◽  
Empty Seed ◽  
Unfertilized Ovules ◽  
Storage Reserves

Many parasitic species of insects complete their entire development in seeds. They feed off storage reserves within the ovule. These reserves only normally accumulate in fertilized ovules. Consequently, female insects that oviposit their eggs directly into the plant ovule need to be able to select correctly, as unfertilized ovules of conifers normally become so-called empty seed. We provide clear evidence that in conifers, seed-parasitizing insects do not need to discriminate between fertilized and unfertilized plant ovules when ovipositing their eggs. A host-specific insect, the chalcid Megastigmus spermotrophus Wachtl (Hymenoptera: Torymidae), lays its eggs in ovules of Douglas fir ( Pseudotsuga menziesii (Mirbel) Franco) before fertilization has taken place in the plant. Oviposition not only prevents the expected degeneration and death of unfertilized ovules, but it induces energy reserve accumulation. Ovules that would otherwise develop as empty seed are redirected in their development by the insect to provide food for the developing larvae. Instead of the insect exploiting normal events during seed development, the insect manipulates seed development for its own reproductive advantage.

scholarly journals FACTORS AFFECTING THE VIABILITY AND GERMINATION BEHAVIOR OF CONIFEROUS SEED. V. SEED MOISTURE CONTENT DURING STRATIFICATION AND SECONDARY STORAGE, PSEUDOTSUGA MENZIESII (MIRB.) FRANCO

1962 ◽  
Vol 38 (3) ◽  
pp. 303-312 ◽  
Author(s):  
G. S. Allen
Keyword(s):  
Moisture Content ◽  
Pseudotsuga Menziesii ◽  
Douglas Fir ◽  
Secondary Storage ◽  
Seed Moisture Content ◽  
Factors Affecting ◽  
Seed Moisture ◽  
And Storage ◽  
Post Stratification

Two seedlots of Douglas fir were each soaked to two levels of moisture content, stratified for 20-120 days at 0-2 °C., subjected to post-stratification storage, and incubated at 10°, 15°, and 25 °C. The higher moisture content (60-70 per cent) was superior for both seedlots particularly when the seed was subjected to drying and storage after stratification. The ability of Douglas fir seed to withstand stratification, drying, and storage for a total time of 240 days, without loss of germinative capacity or vigor, is shown.

The effect of self-, cross-, and no pollination on ovule, embryo, seed, and cone development in western red cedar (Thujaplicata)

1990 ◽  
Vol 20 (1) ◽  
pp. 66-75 ◽  
Author(s):  
John N. Owens ◽  
Anna M. Colangeli ◽  
Sheila J. Morris
Keyword(s):  
Seed Set ◽  
Ovule Development ◽  
Embryo Abortion ◽  
Red Cedar ◽  
Developing Seed ◽  
Stage Of Development ◽  
Cone Development ◽  
History Of ◽  
Nuclear Stage ◽  
Western Red Cedar

The effects of self-, cross-, and no pollination on cone size, filled seed, pollination efficiency, ovule development, and seed efficiency were tested on rooted ramets of six western red cedar (Thujaplicata Donn) clones. To fully develop, ovules must be pollinated with viable pollen and cones must have a minimum of one developing seed. The seed potential was constant among clones and not affected by pollination. The greatest loss of potential seed resulted from a failure of ovules to be pollinated, followed closely by the low percent viability of pollen. Unpollinated ovules aborted at the megaspore or free-nuclear stages. Pollinated ovules may abort at any stage of development, but it was most common during the long free nuclear stage. Selfing had a limited effect on postzygotic loss owing to embryo abortion or on seed set. Western red cedar is well adapted for a high degree of selfing. Clonal differences occurred in seed efficiency and stages at wich seed losses were most commun. Seed set in western red cedar may be increased if cones on female parents having a history of high seed efficiency are pollinated several times within a 1 week peak pollination period with abundant pollen of known high percent viability. Potential seed losses are discussed with reference to pollination and ovule development.

EVALUATION OF FACTORS AFFECTING TREE AND STAND SUSCEPTIBILITY TO THE DOUGLAS-FIR BEETLE (COLEOPTERA: SCOLYTIDAE)

1999 ◽  
Vol 131 (6) ◽  
pp. 831-839 ◽  
Author(s):  
T.L. Shore ◽  
L. Safranyik ◽  
W.G. Riel ◽  
M. Ferguson ◽  
J. Castonguay
Keyword(s):  
Pseudotsuga Menziesii ◽  
Process Model ◽  
Cross Validation ◽  
Biological Process ◽  
Douglas Fir ◽  
Bark Thickness ◽  
Dendroctonus Pseudotsugae ◽  
Factors Affecting ◽  
Site Characteristics ◽  
Tree Characteristics

AbstractTree and site characteristics were compared between 19 groups of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco (Pinaceae), infested by Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, and 19 uninfested groups to identify individual or combinations of characteristics associated with Douglas-fir beetle attacks. Of the tree characteristics, diameter, height, age, phloem thickness, bark thickness, and a standardized variable consisting of diameter divided by the last 10 years growth rate (DBHTYG) showed significant differences. None of the site characteristics showed significant differences between infested and uninfested areas. Two models, identified through discriminant analysis, placed 84 and 87% of the data in the correct infestation groups. These models included the variables diameter, height, phloem thickness, aspect, and DBHTYG in various combinations. The results were confirmed using a jackknifed cross-validation approach. These variables have potential for use in the development of a biological process model of tree and stand susceptibility to the Douglas-fir beetle.

scholarly journals A comparative study on the reproductive success of two rewarding Habenaria species (Orchidaceae) occurring in roadside verge habitats

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wenliu Zhang ◽  
Jiangyun Gao
Keyword(s):  
Reproductive Success ◽  
Fruit Set ◽  
Plant Density ◽  
Flowering Plant ◽  
Floral Display ◽  
Pollinator Behaviour ◽  
Factors Affecting ◽  
Nectar Sugar ◽  
Viable Seeds ◽  
Viable Embryo

Abstract Background Most orchid species have been shown to be severely pollination limited, and the factors affecting reproductive success have been widely studied. However, the factors determining the reproductive success vary from species to species. Habenaria species typically produce nectar but exhibit variable fruit set and reproductive success among species. Here, we investigated the influence of the flowering plant density, inflorescence size, breeding system, and pollinator behaviour on the reproductive success of two rewarding Habenaria species. Results Our observations indicated that Habenaria limprichtii and H. petelotii co-occur in roadside verge habitats and present overlapping flowering periods. Both species were pollination limited, although H. limprichtii produced more fruits than H. petelotii under natural conditions during the 3-year investigation. H. petelotii individuals formed distinct patches along roadsides, while nearly all H. limprichtii individuals clustered together. The bigger floral display and higher nectar sugar concentration in H. limprichtii resulted in increased attraction and visits from pollinators. Three species of effective moths pollinated for H. limprichtii, while Thinopteryx delectans (Geometridae) was the exclusive pollinator of H. petelotii. The percentage of viable seeds was significantly lower for hand geitonogamy than for hand cross-pollination in both species. However, H. limprichtii may often be geitonogamously pollinated based on the behaviours of the pollinators and viable embryo assessment. Conclusions In anthropogenic interference habitats, the behaviours and abundance of pollinators influence the fruit set of the two studied species. The different pollinator assemblages in H. limprichtii can alleviate pollinator specificity and ensure reproductive success, whereas the more viable embryos of natural fruit seeds in H. petelotii suggested reducing geitonogamy by pollinators in the field. Our results indicate that a quantity-quality trade-off must occur between species with different breeding strategies so that they can fully exploit the existing given resources.

scholarly journals Pathogenicity and Virulence of Pythium Species Obtained from Forest Nursery Soils on Douglas-Fir Seedlings

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 744-748 ◽  
Author(s):  
Jerry E. Weiland ◽  
Bryan R. Beck ◽  
Anne Davis
Keyword(s):  
Pseudotsuga Menziesii ◽  
Seedling Survival ◽  
The United States ◽  
Douglas Fir ◽  
Tree Seedlings ◽  
Pythium Species ◽  
Forest Nursery ◽  
Damping Off ◽  
Greenhouse Study ◽  
Forest Nurseries

Pythium species are common soilborne oomycetes that occur in forest nursery soils throughout the United States. Numerous species have been described from nursery soils. However, with the exception of P. aphanidermatum, P. irregulare, P. sylvaticum, and P. ultimum, little is known about the potential for other Pythium species found in nursery soils to cause damping-off of tree seedlings. A greenhouse study was conducted to evaluate the pathogenicity and virulence of 44 Pythium isolates representing 16 species that were originally recovered from soil at three forest nurseries in Washington and Oregon. Seeds of Douglas-fir (Pseudotsuga menziesii) were planted into soil infested with each of the isolates. Seedling survival, the number of surviving seedlings with necrotic root lesions, and taproot length were evaluated 4 weeks later. Responses of Douglas-fir to inoculation varied significantly depending on Pythium species and isolate. Eight species (P. dissotocum, P. irregulare, P. aff. macrosporum, P. mamillatum, P. aff. oopapillum, P. rostratifingens, P. sylvaticum, and P. ultimum var. ultimum) significantly reduced the number of surviving seedlings compared to the noninoculated treatment. However, all Pythium species caused a greater percentage of seedlings to develop root lesions (total mean 40%) than was observed from noninoculated seedlings (17%). Taproot length varied little among Pythium treatments and was not a useful character for evaluating pathogenicity. Results confirm the ability of P. irregulare, P. mamillatum, and P. ultimum var. ultimum to cause damping-off of Douglas-fir seedlings, and are indicative that other species such as P. dissotocum, P. aff. macrosporum, P. aff. oopapillum, P. rostratifingens, and P. sylvaticum may also be responsible for seedling loss.

Cylindrocarpon and Fusarium root colonization of Douglas-fir seedlings from British Columbia reforestation sites

1998 ◽  
Vol 28 (8) ◽  
pp. 1198-1206 ◽  
Author(s):  
Paige E Axelrood ◽  
William K Chapman ◽  
Keith A Seifert ◽  
David B Trotter ◽  
Gwen Shrimpton
Keyword(s):  
British Columbia ◽  
Pseudotsuga Menziesii ◽  
Root Colonization ◽  
Linear Trend ◽  
Poor Performance ◽  
Douglas Fir ◽  
Root Infection ◽  
Significant Linear Trend ◽  
Conifer Seedlings ◽  
Cylindrocarpon Destructans

Poor performance of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantations established in 1987 has occurred in southwestern British Columbia. Affected sites were planted with 1-year-old container stock that exhibited some root dieback in the nursery. A study was initiated in 1991 to assess Cylindrocarpon and Fusarium root infection in planted and naturally regenerating (natural) Douglas-fir seedlings from seven affected plantations. Percentages of seedlings harboring Cylindrocarpon spp.and percent root colonization were significantly greater for planted seedlings compared with natural seedlings. A significant linear trend in Cylindrocarpon root colonization was observed for planted seedlings with colonization levels being highest for roots closest to the remnants of the root plug and decreasing at distances greater than 10cm from that region. This trend in Cylindrocarpon colonization was not observed for natural seedlings. Cylindrocarpon destructans (Zins.) Scholten var. destructans and C.cylindroides Wollenw. var. cylindroides were the only species isolated from planted and natural conifer seedlings. For most sites, percentage of seedlings harboring Fusarium spp.and percent Fusarium root colonization were less than for Cylindrocarpon. Recovery of Fusarium spp.from seedlings and root colonization levels were not significantly different for planted and natural seedlings from all sites.

Factors affecting pollinator visitation and reproductive success in Sonneratia caseolaris and Aegiceras corniculatum in a mangrove forest in India

2001 ◽  
Vol 17 (3) ◽  
pp. 431-447 ◽  
Author(s):  
SHALINI PANDIT ◽  
B. C. CHOUDHURY
Keyword(s):  
Reproductive Success ◽  
Mangrove Forest ◽  
Time Of Day ◽  
Pollinator Visitation ◽  
Aegiceras Corniculatum ◽  
Factors Affecting ◽  
Plant Reproductive Success ◽  
Sonneratia Caseolaris ◽  
Exclusion Experiments ◽  
Selfing Species

Pollinator visitation to, and the reproductive success of, Sonneratia caseolaris (Sonneratiaceae) and Aegiceras corniculatum (Myrsinaceae) was investigated in a mangrove forest in India. S. caseolaris was shown to be primarily outcrossed and A. corniculatum was shown to be a selfing species. The flowers of both plant species attracted several diurnal and nocturnal visitors. Earlier reports had indicated that S. caseolaris flowered for one night and was exclusively night-pollinated. But flowers of this species were found to be in bloom both at night and during the day, and diurnal visitors to the flowers were more diverse and frequent than nocturnal ones. This was related to the higher volume and energy value of nectar in the morning. The effects of time of day and temperature on visitation rates were quantified. The importance of visitors to plant reproductive success was investigated via controlled visitor-exclusion experiments. Pollinators were expected to be more important for the outcrossing species than for the selfing species, and this was confirmed by the results of the exclusion experiments. In S. caseolaris reproductive success was determined both by pollinator availability and the intensity of flower and fruit predation, while in A. corniculatum it is likely to be resource limited.

scholarly journals High-Moisture Meat Analogues Produced from Yellow Pea and Faba Bean Protein Isolates/Concentrate: Effect of Raw Material Composition and Extrusion Parameters on Texture Properties

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 843
Author(s):  
Ferawati Ferawati ◽  
Izalin Zahari ◽  
Malin Barman ◽  
Mohammed Hefni ◽  
Cecilia Ahlström ◽  
...  
Keyword(s):  
Faba Bean ◽  
Genetically Modified Organisms ◽  
Extrusion Process ◽  
Raw Material ◽  
High Moisture ◽  
Protein Isolates ◽  
Factors Affecting ◽  
Texture Properties ◽  
Meat Analogue ◽  
Bean Protein

Yellow pea and faba bean are potential candidates to replace soybean-based ingredients due to their suitability for cultivation in the northern hemisphere, non-genetically modified organisms cultivation practice and low risk of allergenicity. This study examined the functionality of local yellow pea and faba bean protein isolates/concentrate as meat analogue products. The most critical factors affecting the texture properties of meat analogue were also determined. Extrusion was used to produce high-moisture meat analogues (HMMAs) from yellow pea and faba bean protein isolates/concentrates and HMMAs with fibrous layered structures was successfully produced from both imported commercial and local sources. The texture properties of the HMMA produced were mainly affected by the ash, fiber and protein content and water-holding capacity of the source protein. Three extrusion process parameters (target moisture content, extrusion temperature, screw speed), also significantly affected HMMA texture. In conclusion, functional HMMA can be produced using protein isolates derived from locally grown pulses.

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