The use of mitotic index in seedling assessments

1994 ◽  
Vol 24 (11) ◽  
pp. 2222-2234 ◽  
Author(s):  
Marek J. Krasowski ◽  
John N. Owens
Keyword(s):  
Mitotic Index ◽  
Treatment Effects ◽  
White Spruce ◽  
Good Alternative ◽  
Day Length ◽  
Late Winter ◽  
Bud Break ◽  
Nursery Culture ◽  
Red Cedar ◽  
Seed Sources

The daytime pattern of mitotic index (MI) (percent of apical cells undergoing mitosis) in the shoot apex of Piceaglauca (Moench) Voss (white spruce) containerized seedlings was examined and compared for five cultural treatments. From sowing in March until mid-July, all seedlings were grown under an extended, 23-h photoperiod in a common nursery culture. In mid-July, an array of photoperiod treatments was created, ranging from ambient photoperiod and temperature to different levels of short day length and ambient or controlled, constant temperature. Consistency of MI comparisons among the treatments at different specimen collection times was emphasized rather than treatment effects on MI. Specimens were collected four times a day on two dates: when most seedlings in all treatments were initiating bud scales and when most seedlings were initiating leaf primordia. Patterns of MI were different on each of these dates. It is shown that conclusions about treatment effects on MI can be influenced by the sampling protocol and analytical approach. End of the growing season studies of white spruce and P. glauca × Piceasitchensis (Bong.) Carr. (white × Sitka spruce hybrid) seedlings grown in a greenhouse culture showed that MI below 1% was well correlated with low (<25%) foliage damage, reasonably correlated with stem tissue damage, and not correlated with bud damage resulting from controlled freezer tests to −18 °C. It is concluded that the MI technique could be useful in lifting-date determination, but different MI thresholds must be established for southern, northern, or coastal seed sources. Monitoring MI was not a good alternative to using days to bud break (testing under forcing conditions) to determine bud dormancy status. However, mitotic reactivation of the apical meristem in seedlings overwintering in a nursery bed occurred earlier in the spring than visible signs of growth reactivation (bud swelling and bud break). Studies of growth resumption of western red cedar (Thujaplicata Donn) seedlings in winter revealed that this species would be considered quiescent if tested under a long photoperiod, while under a short photoperiod growth resumption was much slower in early than in mid- and late winter.

Dormancy release and growth responses of 3+0 bare-root white spruce (Piceaglauca) seedlings subjected to moisture stress before freezer storage

1992 ◽  
Vol 22 (1) ◽  
pp. 132-137 ◽  
Author(s):  
Robin Rose ◽  
Steven K. Omi ◽  
Barry Court ◽  
Kathy Yakimchuk
Keyword(s):  
Storage Period ◽  
White Spruce ◽  
Moisture Stress ◽  
Seed Source ◽  
Bud Break ◽  
Dormancy Release ◽  
Growth Responses ◽  
Freezer Storage ◽  
Seed Sources ◽  
Plant Moisture

Greenhouse and field experiments were conducted with white spruce (Piceaglauca (Moench) Voss) seedlings from three seed sources to determine how plant moisture stress before storage and length of freezer storage (8–209 days) affect dormancy release and growth responses of outplanted seedlings. During storage, plant water potential remained lower (more negative) in seedlings subjected to high prestorage plant moisture stress than in those subjected to low prestorage plant moisture stress. However, as duration of storage increased, overall plant moisture stress declined. High prestorage plant moisture stress had little influence on dormancy except to delay terminal bud break in seedlings from the southernmost seed source by 10% and, after an 8-day storage period, to delay bud break of seedlings by 15% compared with the low moisture stress treatment. Seed source and storage period were associated with the greatest variation in growth. The central seed source produced more growth in height and biomass than the other seed sources. Better height growth of seedlings subjected to high moisture stress was attained after all but the 8-day storage period. Seedling responses were complex and not clearly related to their performance in nursery and field outplantings.

Temperature/light interactions and the effect of seed source on germination of annual ryegrass (Lolium rigidum Gaud.) seeds

1976 ◽  
Vol 27 (6) ◽  
pp. 779 ◽  
Author(s):  
D Gramshaw
Keyword(s):  
Constant Temperature ◽  
Day Length ◽  
Maximum Temperature ◽  
Annual Ryegrass ◽  
Lolium Rigidum ◽  
Average Temperature ◽  
Seed Sources ◽  
Alternating Temperature ◽  
Germinating Seeds ◽  
Temperature Optima

Germination of Lolium rigidum seeds, in the light (12 hr day length) and in the dark, was studied at constant and alternating (12/12 hr) temperatures in the range 8–35°C. Seeds had after-ripened for 22 weeks. Different constant temperature optima for germinability were found: 27° in light and 11° in dark. Germinability at alternating temperatures in darkness was determined solely by the minimum temperature of the alternation, and there was no response to thermoperiodicity per se. In contrast, light and alternating temperature appeared to interact to increase germinability, although the highest germinability occurred only when the maximum temperature was close to the optimum constant temperature, i.e. about 27°. Germination in both light and dark was most rapid where either the constant or the average temperature of an alternating regime was between 18 and 29°. Below 18° germination rates decreased markedly, and at 8°, rates were one-third of those at 18°. Seeds germinated more slowly in light than in darkness at all temperatures, but the differences were small relative to the effects of low temperatures.In another study, seeds collected from plants naturalized in eight different localities in the cereal belt of Western Australia and subsequently planted together in two contrasting environments were examined for germinability at 24/12°C in light and dark 18 weeks after harvest. Dark germinability differed between seed sources but not between planting sites, and ranged between 78 and 93%. Exposure of germinating seeds to light substantially alleviated dormancy in seeds from all sources.

Influence of nursery culture on western red cedar

New Forests ◽  
1994 ◽  
Vol 8 (3) ◽  
pp. 231-247 ◽  
Author(s):  
Raymund S. Folk ◽  
Steven C. Grossnickle ◽  
John E. Major ◽  
James T. Arnott
Keyword(s):  
Nursery Culture ◽  
Red Cedar ◽  
Western Red Cedar

scholarly journals Cold hardiness of white spruce, black spruce, jack pine, and lodgepole pine needles during dehardening

2017 ◽  
Vol 47 (8) ◽  
pp. 1116-1122 ◽  
Author(s):  
Rongzhou Man ◽  
Pengxin Lu ◽  
Qing-Lai Dang
Keyword(s):  
Picea Glauca ◽  
Pinus Banksiana ◽  
Cold Hardiness ◽  
Black Spruce ◽  
Lodgepole Pine ◽  
White Spruce ◽  
Visual Assessment ◽  
Jack Pine ◽  
Pine Needles ◽  
Late Winter

Conifer winter damage results primarily from loss of cold hardiness during unseasonably warm days in late winter and early spring, and such damage may increase in frequency and severity under a warming climate. In this study, the dehardening dynamics of lodgepole pine (Pinus contorta Dougl. ex. Loud), jack pine (Pinus banksiana Lamb.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) B.S.P.) were examined in relation to thermal accumulation during artificial dehardening in winter (December) and spring (March) using relative electrolyte leakage and visual assessment of pine needles and spruce shoots. Results indicated that all four species dehardened at a similar rate and to a similar extent, despite considerably different thermal accumulation requirements. Spring dehardening was comparatively faster, with black spruce slightly hardier than the other conifers at the late stage of spring dehardening. The difference, however, was relatively small and did not afford black spruce significant protection during seedling freezing tests prior to budbreak in late March and early May. The dehardening curves and models developed in this study may serve as a tool to predict cold hardiness by temperature and to understand the potential risks of conifer cold injury during warming–freezing events prior to budbreak.

The effect of failure in extended and intermittent photoperiodic lighting on the growth of white spruce container seedlings

1985 ◽  
Vol 15 (4) ◽  
pp. 734-737 ◽  
Author(s):  
J. T. Arnott ◽  
C. S. Simmons
Keyword(s):  
Dark Period ◽  
Dry Weight ◽  
White Spruce ◽  
Shoot Length ◽  
Day Length ◽  
Lighting System ◽  
Usual Definition ◽  
Short Day ◽  
Lighting Systems ◽  
Definition Of

White spruce seedlings (seed source, 58°50′ N) were grown in a container nursery at Victoria, B.C. (48°28′ N) under the following two photoperiod regimes: (i) natural day length artifically extended to 18 h (120 lx from an incandescent source); (ii) natural day length with dark period interruption for 2.5 min every 30 min (120 lx from an incandescent source). Beginning on July 17, 12 weeks after sowing, batches of seedlings experienced a simulated failure of the lighting systems of from 0 to 9 nights. Although the reduced photoperiod did not fit the usual definition of a short day, failure of the lighting system in (i) and (ii) caused significant reductions in seedling shoot length and dry weight and a significant increase in root dry weight.

Dispersal of eastern red cedar (Juniperus virginiana) into pastures: an overview

1987 ◽  
Vol 65 (6) ◽  
pp. 1092-1095 ◽  
Author(s):  
Anthonie M. A. Holthuijzen ◽  
Terry L. Sharik ◽  
James D. Fraser
Keyword(s):  
Growing Season ◽  
Seed Banks ◽  
Physiological Adaptation ◽  
Juniperus Virginiana ◽  
Similar Distribution ◽  
Eastern Red Cedar ◽  
Red Cedar ◽  
Seed Sources ◽  
Seed Shadows ◽  
Recovered Material

Seed dispersal, predispersal and postdispersal seed predation, seed dormancy, and germination were followed for four cone-bearing eastern red cedar trees (Juniperus virginiana L.), a predominantly avian-dispersed plant species, in pastures in southwest Virginia from June 1981 through May 1982. Within 12 m from the source trees, 34.7% of the total cone crop was recovered. Recovered material consisted of unripe cones, ripe cones, parasitized cones, and pulpless seeds evacuated by birds, averaging 17.9, 11.6, 1.0, and 4.2%, respectively, of the cone crop. Predispersal avian predation of seeds accounted for 3.1% of the cone crop. After 1 year 0.9% of the cones remained on the trees. The remaining 61.3% of the cone crop was dispersed at least 12 m from the source trees. Less than 3% of the cone crop is likely to germinate within 12 m of the source trees, while about 25% is likely to germinate at greater distances. Red cedar seeds passed unharmed through the digestive tract of avian dispersers and showed greater total germination than manually depulped seeds. Red cedar seed banks were not found under a chronosequence of red cedar stands; seeds generally lost their viability within one growing season. Seed shadows decreased exponentially with distance from cone-bearing trees. A similar distribution function was reflected in the spatial distribution of red cedar cohorts colonizing pastures near source trees. The large cone crop, diverse avian disperser assemblage, physiological adaptation of red cedar to open, xeric sites, and availability of seed sources in fence rows contribute to the successful invasion of pastures by this species.

Geographic patterns of variation in allozymes and height growth in white spruce

1991 ◽  
Vol 21 (5) ◽  
pp. 707-712 ◽  
Author(s):  
Glenn R. Furnier ◽  
Michael Stine ◽  
Carl A. Mohn ◽  
Merlise A. Clyde
Keyword(s):  
White Spruce ◽  
Allozyme Variation ◽  
Allozyme Data ◽  
Evolutionary Forces ◽  
Seed Sources ◽  
Genotype Frequencies ◽  
Provenance Test ◽  
Hardy Weinberg Equilibrium ◽  
Allozyme Loci ◽  
Height Data

Variation in height at ages 9 and 19 years and at six polymorphic allozyme loci was examined for 22 seed sources (populations) in a range-wide white spruce (Piceaglauca (Moench) Voss) provenance test planted in Minnesota. There were strong differences among populations for height, with 48.0 and 54.1 % of the genetic variation for height at ages 9 and 19, respectively, due to differences among populations. Mean observed and expected estimates of allozyme heterozygosity were 0.306 and 0.290, respectively, with little deviation from genotype frequencies expected under a Hardy–Weinberg equilibrium. In contrast with the height data, an average of only 3.8% of this variation was due to differences among populations. Geographic trends were apparent in the height data, with northern and western sources performing the poorest. Neither univariate nor multivariate analyses revealed any geographic trends in the allozyme data. The very different distributions for height and allozyme variation suggest that evolutionary forces are acting in different ways on the genes controlling these traits, and that allozyme data will have limited value in developing sampling strategies for gene conservation programs, where the preservation of germ plasm adapted to many sites throughout a species range is important.

scholarly journals Seasonal Effects of Transplanting on Northern Red Oak and Willow Oak

2004 ◽  
Vol 22 (2) ◽  
pp. 75-79
Author(s):  
Lisa E. Richardson-Calfee ◽  
J. Roger Harris ◽  
Jody K. Fanelli
Keyword(s):  
Root Growth ◽  
Early Spring ◽  
Height Growth ◽  
Seasonal Effects ◽  
Late Winter ◽  
Red Oak ◽  
Bud Break ◽  
Northern Red Oak ◽  
Trunk Diameter ◽  
Red Oaks

Abstract Seasonal effects on transplant establishment of balled-and-burlapped (B&B) shade trees are not well documented. Early post-transplant root growth and aboveground growth over a 3-year period were therefore determined for November-and March-transplanted northern red oak (Quercus rubra L.) and willow oak (Q. phellos L.). Survival of red oak was 100% for both treatments. Survival of November-and March-transplanted willow oak was 67% and 83%, respectively. No new root growth was observed outside or within the root balls of either species upon excavation in January. New root growth was evident when trees of both species were excavated in April, indicating that root system regeneration of November-transplanted trees occurs in late winter and/or early spring, not late fall and/or early winter. November-transplanted red oak, but not willow oak, grew more roots by spring bud break than March-transplanted trees. However, little difference in height growth and trunk expansion was evident between the November-and March-transplanted red oaks throughout the 3 years following transplant. While height growth of willow oak was nearly identical between treatments after 3 years, November transplants exhibited greater trunk diameter increase for all 3 years. Overall, season of transplant had little effect on height and trunk diameter increase of red oak, even though November-transplanted trees grew more roots prior to the first bud break following transplant. Among the willow oaks that survived, season of transplant had little effect on new root growth and height growth, but November transplanting resulted in greater trunk expansion. However, when the mortality rate of November-transplanted willow oak is taken into consideration, March may be a better time to transplant willow oak in climates similar to southwest Virginia.

scholarly journals Photoperiod and its relationship to sheep reproduction

2021 ◽  
Author(s):  
Anayansi Ivette Ramírez Ramírez ◽  
Tania Arellano Lezama ◽  
Zadi Méndez Roblero1 ◽  
Guadalupe Idilia Delgado Tiburcio ◽  
Jaime Gallegos-Sánchez
Keyword(s):  
Animal Species ◽  
Reproductive Activity ◽  
Early Spring ◽  
Climatic Conditions ◽  
Day Length ◽  
Late Winter ◽  
Environmental Cues ◽  
Factors Affecting ◽  
Common Process ◽  
Almost Continuous

Objective: To describe the seasonal variations throughout the year (day length), as one of the main environmental cues used by ewes to determine the most favorable time for breeding. Design/methodology/approach: A description of the main factors affecting ewe reproduction (photoperiod, suckling, postpartum period, nutrition, sociosexual effects) was assessed by a review of documentary information. Results: The inhibition of reproductive activity during one time of the year is a common process in most animal species to prevent births from occurring at an unfavorable time for the survival of the offspring. The seasonality of reproduction (northern latitude) allows births to occur in late winter or early spring when climatic conditions are the most favorable for the offspring development. Limitations/implications: The duration of the anestrus season (seasonal or postpartum) is influenced by the photoperiod and other factors. In Mexico, a small percentage of Criollo and Pelibuey ewes show a short duration of seasonal anestrus; that is, they show almost continuous annual reproductive activity. Therefore, to improve the reproductive efficiency of ewes, it is important to precisely determine the factors that affect their reproduction to improve management and increase the profits in the production units. Findings/Conclusions: Photoperiod is the main environmental factor regulating the annual reproductive cycle of the ewes, it occurs through very complex and varied mechanisms that communicate the visual system with the gonads through nervous and endocrine pathways.

Sign in / Sign up

Export Citation Format

Share Document