Influence of photoperiod on shoot and root frost tolerance and bud phenology of white spruce seedlings (Piceaglauca)

1993 ◽  
Vol 23 (2) ◽  
pp. 219-228 ◽  
Author(s):  
Francine J. Bigras ◽  
André L. D'Aoust

To determine frost tolerance of shoots and roots and the phenology of apical buds under different photoperiods during hardening and dehardening, 16-week-old white spruce seedlings (Piceaglauca (Moench) Voss) were hardened in growth chambers under 8-, 10-, 12-, and 14-h photoperiods for 14 d at 15:10 °C, followed by 14 d at each of the day:night temperatures of 12:8 °C, 10:5 °C, 5:2 °C under 13-h photoperiod, and finally, stored for 35 d at 0:0 °C in darkness. Afterwards, deacclimation conditions consisted of 14 d at 10:5 °C and 17 d at 15:10 °C with 15-h photoperiod. Frost tolerance was assessed at intervals, and phenology of apical buds was monitored by visual examination. The root dry mass remaining after removal of dead tissue was weighed 30 d after the freezing test to estimate frost damage to the root system. Results showed that hardening of shoots was influenced by photoperiod, whereas hardening of roots responded only to temperature. Frost tolerance of shoots was enhanced and bud formation accelerated under 8-h photoperiod. After 56 d of acclimation, frost tolerance of shoots reached −30, −17, −17, and −12 °C under photoperiods of 8, 10, 12, and 14 h, respectively. Bud break occurred earlier, in a similar fashion for plants treated with 8- and 10-h photoperiods. The root dry mass remaining after removal of dead tissue provided a reliable estimate of frost damage to root systems. Finally, we propose that short-day treatment accelerates and long-day treatment delays the dormancy development, thus causing all developmental processes to be affected. Consequently, hardiness development can also be accelerated by short-day treatment or delayed by long-day treatment, resulting in faster rates of hardening, dehardening, and bud break for seedlings of the short-day treatment, whereas long-day treatment delays those processes. These results complement the analysis of dehardening and bud break in the degree growth stage model described by L.H. Fuchigami and coworkers.

1992 ◽  
Vol 22 (3) ◽  
pp. 388-396 ◽  
Author(s):  
Francine J. Blgras ◽  
André L. D'aoust

Containerized black spruce (Piceamariana (Mill.) B.S.P.) and white spruce (Piceaglauca (Moench) Voss) seedlings that were 120 days old were acclimated under short-day (8-h photoperiod) and long-day (16-h photoperiod) conditions at 10 °C for 12 h and 5 °C for 12 h for 28 days. Afterwards, they were exposed to 3 °C (8-h photoperiod) for 21 days and to 0 °C (without light) for 28 days. Finally, seedlings were dehardened at 10 °C (14-h photoperiod) for 21 days. Hardening of needles, excised stem parts, and whole seedlings was increased by short-day treatment, whereas roots hardened only in response to lowering of temperature. Whole seedlings and needles exposed to the short-day treatment dehardened earlier, whereas roots dehardened only in response to temperature changes. Bud formation was not influenced by photoperiod treatment, but seedlings exposed to the short-day treatment had an earlier bud break. No significant difference was observed between photoperiod treatments for water, sugar, and mineral content of shoots and roots prior to or during dehardening.


1983 ◽  
Vol 10 (2) ◽  
pp. 59-62 ◽  
Author(s):  
H. T. Stalker ◽  
J. C. Wynne

Abstract Many Arachis species collections do not produce pegs in North Carolina even though they flower profusely. To investigate reasons for the failure of fruiting, nine wild peanut species of section Arachis and three A. hypogaea cultivars representing spanish, valencia and virginia types were evaluated for response to short and long-day treatments in the North Carolina State Phytotron Unit of the Southeastern Environmental Laboratories. The objective of this investigation was to determine the flowering and fruiting responses of Arachis species to short and long-day photoperiods. Plant collections grown under a 9-hour short-day treatment were generally less vigorous, but produced more pegs than corresponding plants grown in long-day treatments which were produced by 9 hours of light plus a 3-hour interruption of the dark period. Annual species produced significantly more flowers and pegs than perennial species during both long and short days. The total number of flowers produced ranged from 0 during short days for A. correntina to more than 300 for A. cardenasii in long-day treatments. Only one plant of each species A. chacoense and A. villosa, and no plants of A. correntina, flowered in short days. Total numbers of pegs produced in short-day treatments were generally greater than in long-day treatments and the ratio of total number of pegs/total number of flowers was consistently greater during short-day treatments. A general trend was observed for more flowers produced in long-day treatments, but more pegs produced in short days. This study indicated that photoperiod can be manipulated to increase the seed set of some species and the success rate of obtaining certain interspecific hybrids. Furthermore, introgression from wild to cultivated species may possibly alter the reproductive capacity of A. hypogaea to photoperiod.


1995 ◽  
Vol 73 (2) ◽  
pp. 183-199 ◽  
Author(s):  
Heikki Hänninen

A framework is presented for modelling bud burst phenology of trees from the cool and temperate regions. Three ecophysiological aspects affecting the timing of bud burst are considered: (i) effects of environmental factors on the rest status of the bud, (ii) effect of rest status on the ability for bud burst, and (iii) direct effect of air temperature on the rate of development towards bud burst. Any model for bud burst phenology can be presented within the framework with three submodels, each of them addressing one of the corresponding three ecophysiological aspects. A total of 96 hypothetical models were synthesized by combining submodels presented in the literature. The models were tested in two experiments with saplings of Pinus sylvestris L. growing in experimental chambers at their natural site in eastern Finland. In the first experiment, air temperature and (or) concentration of atmospheric CO2 was elevated. Elevation of the air temperature hastened bud burst, whereas elevation of the concentration of CO2 did not affect it. Several models accurately predicted the timing of bud burst for natural conditions but too early for bud burst at the elevated temperatures. This finding suggests that (i) the risk of a premature bud burst with subsequent frost damage, as a result of climatic warming, was overestimated in a recent simulation study, and (ii) bud burst observations in natural conditions alone are not sufficient for the testing of these mechanistic models. Several models did predict the timing of bud burst accurately for all treatments, but none of them obtained sufficiently strong support from the findings to stand out as superior or uniquely correct. In the second experiment a photoperiod submodel for rest break was tested by exposing the saplings to short-day conditions. The short-day treatment had only a minor effect on the timing of bud burst. These results demonstrated the importance of the concept of model realism: the accuracy of a model can be lost in new conditions (e.g., global warming), unless the model correctly addresses the essential ecophysiological aspects of the regulation of timing of bud burst. Key words: annual cycle of development, chilling, dormancy, field test, photoperiod, rest break.


2009 ◽  
Vol 89 (6) ◽  
pp. 1031-1039 ◽  
Author(s):  
A K Bergjord ◽  
A K Bakken ◽  
A O Skjelvåg

The quantitative nature of the vernalization and photoperiod requirements and the interference of plant age with these mechanisms complicate predictions of generative induction and its relation to frost tolerance. This study was designed to dissect further the course of development towards full generative induction and to time the stages in frost tolerance. Two cultivars of winter wheat were regularly sampled from fields at four sites during three winters. The apex stage of development was observed at time of sampling and after 3 subsequent weeks of growth at 18°C, under either short or long days. Level of frost tolerance at sampling was also recorded. No visible change in apex appearance was found at time of sampling, but readiness of plants to initiate generative development was enhanced. Vernalization by low temperatures alone was not enough to induce the plants into generative development or initiate loss of frost tolerance. Short day conditions after sampling delayed the appearance of double ridges by 6-9 wk as compared with long day conditions. The timing of maximum frost tolerance and its subsequent decrease indicated that generative induction under the short day conditions prevailing in field occurred about 1 mo after vernalization saturation.Key words: Triticum aestivum L., frost tolerance, generative induction, vernalization, photoperiod


1960 ◽  
Vol 38 (4) ◽  
pp. 597-599 ◽  
Author(s):  
O. Vaartaja

Seedlings of Picea glauca were grown for 2 months under three photoperiodic treatments. Short day treatment induced early terminal dormancy and resistance to severe drought treatment. Long day treatments, on the other hand, allowed prolonged growth of most seedlings and made them susceptible to drought.


HortScience ◽  
2011 ◽  
Vol 46 (3) ◽  
pp. 416-419 ◽  
Author(s):  
Ariana P. Torres ◽  
Roberto G. Lopez

Tecoma stans (L. Juss. Kunth) ‘Mayan Gold’ is a tropical flowering plant that was selected as a potential new greenhouse crop for its physical appearance and drought and heat tolerance. The objective of this study was to quantify how temperature during the finishing stage and photoperiod during propagation and finishing stages influence growth, flowering, and quality. In Expt. 1, plants were propagated from seed under four photoperiods (9, 12, 14, or 16 h) for 35 days. Under long-day (LD) photoperiods (14 h or greater), seedlings were 3.0 to 3.7 cm taller than those propagated under 9-h photoperiods. During the finishing stage, days to first open flower, shoot dry mass, and number of nodes below the terminal inflorescence were reduced when plants were grown under LD photoperiods. In addition, number of open flowers and branches increased under LD photoperiods. Few plants developed visible buds when grown under short-day (SD) photoperiods (12 h or less). In Expt. 2, plants were forced at average daily temperatures of 19, 20, or 22 °C after transplant. Time to first open flower was reduced by 7 days as temperature increased. Inversely, number of visible buds increased by 57 as temperature increased from 19 to 22 °C. Under the experimental conditions tested, the most rapid, complete, and uniform flowering of Tecoma occurred when plants were propagated and finished under LD photoperiods and forced at 22 °C.


HortScience ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 710-715 ◽  
Author(s):  
Philip A. Stack ◽  
Francis A. Drummond ◽  
Lois Berg Stack

The application of supplemental blue light in greenhouse chrysanthemum production is part of a biological control strategy to enhance reproduction of Orius insidiosus Say, a natural predator of the western flower thrips, Frankliniella occidentalis Pergande. Two greenhouse experiments were conducted to determine the influence of a blue light—supplemented long day on flowering and vegetative growth in three cultivars of the short-day plant Dendranthema ×grandiflora (Ramat.) Kitamura. In Expt. 1, two cut chrysanthemum cultivars (`Manatee Iceberg' and `Naples') were exposed to: a) 9-hour ambient light and 15-hour artificial blue-biased (400-500 nm) light at two blue light intensities (3.6 or 7.0 μmol·m-2·s-1); b) 9-hour ambient light and 15-hour artificial broad spectrum light at a broad spectrum intensity of 3.6 μmol·m-2·s-1; c) 9-hour ambient light maintained with black cloth; or d) an ambient short day. Under a continuous photoperiod, flower initiation in both cultivars in the lower intensity blue light was not significantly different from that in short-day regimes. However, in both blue light intensities, flower size and dry mass were significantly less than in the short-day regimes. Increasing the dose of blue light decreased flower dry mass in `Naples' by 60% and in `Manatee Iceberg' by 72%. Plants were shorter with less vegetative mass in the short-day regimes. In Expt. 2, `Naples' and the pot chrysanthemum `Boaldi' were exposed to a) 9-hour ambient light and 6-hour artificial blue-biased (400-500 nm) light at four blue light intensities (0.4, 0.7, 1.6, or 3.5 μmol·m-2·s-1); b) 9-h ambient light maintained with black cloth; or c) an ambient long day. For both cultivars, in all blue light regimes, neither flower dry mass nor vegetative dry mass differed significantly from those in the short-day regime. The results indicate that exposing D. grandiflora to a blue light—supplemented long day at blue light intensities <3.5 μmol·m-2·s-1 does not adversely affect flower initiation and development.


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