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Effect of alternating day and night temperature on short day-induced bud set and subsequent bud burst in long days in Norway spruce.

Olsen JE, Lee Y, Junttila O - Front Plant Sci (2014)

Bottom Line: Although no specific effect of alternating DT/NT was found, the results demonstrate that the effects of DT under SD on bud set and subsequent bud break are significantly modified by NT in a complex way.The present results also indicate that low temperature during bud development had a larger effect on the most southern compared to the most northern provenance studied.In conclusion, being a highly temperature-dependent process, bud development is strongly delayed by low temperature, and the effects of DT is significantly modified by NT in a complex manner.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, Norwegian University of Life Sciences Ås, Norway.

ABSTRACT
Young seedlings of the conifer Norway spruce exhibit short day (SD)-induced cessation of apical growth and bud set. Although different, constant temperatures under SD are known to modulate timing of bud set and depth of dormancy with development of deeper dormancy under higher compared to lower temperature, systematic studies of effects of alternating day (DT) and night temperatures (NT) are limited. To shed light on this, seedlings of different provenances of Norway spruce were exposed to a wide range of DT-NT combinations during bud development, followed by transfer to forcing conditions of long days (LD) and 18°C, directly or after different periods of chilling. Although no specific effect of alternating DT/NT was found, the results demonstrate that the effects of DT under SD on bud set and subsequent bud break are significantly modified by NT in a complex way. The effects on bud break persisted after chilling. Since time to bud set correlated with the daily mean temperature under SD at DTs of 18 and 21°C, but not a DT of 15°C, time to bud set apparently also depend on the specific DT, implying that the effect of NT depends on the actual DT. Although higher temperature under SD generally results in later bud break after transfer to forcing conditions, the fastest bud flush was observed at intermediate NTs. This might be due to a bud break-hastening chilling effect of intermediate compared to higher temperatures, and delayed bud development to a stage where bud burst can occur, under lower temperatures. Also, time to bud burst in un-chilled seedlings decreased with increasing SD-duration, suggesting that bud development must reach a certain stage before the processes leading to bud burst are initiated. The present results also indicate that low temperature during bud development had a larger effect on the most southern compared to the most northern provenance studied. Decreasing time to bud burst was observed with increasing northern latitude of origin in un-chilled as well as chilled plants. In conclusion, being a highly temperature-dependent process, bud development is strongly delayed by low temperature, and the effects of DT is significantly modified by NT in a complex manner.

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Time to 50% bud burst in seedlings of Norway spruce as affected by temperature during short day treatment. Results are means of all three provenances, and are plotted against the daily mean temperature for the 3 day temperature treatments (15, 18, and 21°C, which were combined with NT of 6, 9, 12, 15, 18, and 21°C, i.e., up to 15, 18, and 21°C for the DT 15, 18, and 21°C, respectively). Seedlings were not chilled before forcing (18°C, 24 h photoperiod). Vertical bars give the critical difference (P = 0.05) for night temperatures (NT) within the 3 day temperatures.
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Figure 2: Time to 50% bud burst in seedlings of Norway spruce as affected by temperature during short day treatment. Results are means of all three provenances, and are plotted against the daily mean temperature for the 3 day temperature treatments (15, 18, and 21°C, which were combined with NT of 6, 9, 12, 15, 18, and 21°C, i.e., up to 15, 18, and 21°C for the DT 15, 18, and 21°C, respectively). Seedlings were not chilled before forcing (18°C, 24 h photoperiod). Vertical bars give the critical difference (P = 0.05) for night temperatures (NT) within the 3 day temperatures.

Mentions: In general, time to 50% bud burst increased with increasing temperature applied during the SD period (Figure 2; Tables 3 and 4). In un-chilled plants, exposure to a DT of 21°C under SD resulted in later bud burst, i.e., 24–26 days after transfer to forcing, compared to treatments with lower DT where bud burst was observed after 19–22 days, except 18/6°C DT/NT, which showed bud burst after 24 days (as averaged for the three provenances; Figure 2). In addition, there was a significant effect of NT. Bud burst was fastest in seedlings exposed to intermediate NT, irrespective of DT, and bud burst was delayed both by lower (6°C) and higher NT. In the un-chilled plants, the largest differences between NTs were observed for the DT of 15°C, for which the NT of 9°C resulted in the most rapid bud burst, (after about 19 days of forcing), compared to the slowest (after about 22 days) for NTs of 6°C and 15°C (Figure 2). The effect of temperature treatment applied during the SD period was significant even after chilling (Figure 3). The situation with slowest bud burst for higher and lower temperature under SD, compared to intermediate, was generally similar to in un-chilled plants (Figure 3). Also, like for un-chilled plants, the time to 50% bud burst in chilled plants increased with increasing temperature, but this relationship was most clear for the low NTs provided under SD. Generally, time to 50% bud burst decreased with increasing duration of chilling (Figure 4). Differences between provenances remained also after chilling; bud burst was earliest in the northernmost provenance P1 and latest in southernmost provenance F1 (Table 4).


Effect of alternating day and night temperature on short day-induced bud set and subsequent bud burst in long days in Norway spruce.

Olsen JE, Lee Y, Junttila O - Front Plant Sci (2014)

Time to 50% bud burst in seedlings of Norway spruce as affected by temperature during short day treatment. Results are means of all three provenances, and are plotted against the daily mean temperature for the 3 day temperature treatments (15, 18, and 21°C, which were combined with NT of 6, 9, 12, 15, 18, and 21°C, i.e., up to 15, 18, and 21°C for the DT 15, 18, and 21°C, respectively). Seedlings were not chilled before forcing (18°C, 24 h photoperiod). Vertical bars give the critical difference (P = 0.05) for night temperatures (NT) within the 3 day temperatures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4260492&req=5

Figure 2: Time to 50% bud burst in seedlings of Norway spruce as affected by temperature during short day treatment. Results are means of all three provenances, and are plotted against the daily mean temperature for the 3 day temperature treatments (15, 18, and 21°C, which were combined with NT of 6, 9, 12, 15, 18, and 21°C, i.e., up to 15, 18, and 21°C for the DT 15, 18, and 21°C, respectively). Seedlings were not chilled before forcing (18°C, 24 h photoperiod). Vertical bars give the critical difference (P = 0.05) for night temperatures (NT) within the 3 day temperatures.
Mentions: In general, time to 50% bud burst increased with increasing temperature applied during the SD period (Figure 2; Tables 3 and 4). In un-chilled plants, exposure to a DT of 21°C under SD resulted in later bud burst, i.e., 24–26 days after transfer to forcing, compared to treatments with lower DT where bud burst was observed after 19–22 days, except 18/6°C DT/NT, which showed bud burst after 24 days (as averaged for the three provenances; Figure 2). In addition, there was a significant effect of NT. Bud burst was fastest in seedlings exposed to intermediate NT, irrespective of DT, and bud burst was delayed both by lower (6°C) and higher NT. In the un-chilled plants, the largest differences between NTs were observed for the DT of 15°C, for which the NT of 9°C resulted in the most rapid bud burst, (after about 19 days of forcing), compared to the slowest (after about 22 days) for NTs of 6°C and 15°C (Figure 2). The effect of temperature treatment applied during the SD period was significant even after chilling (Figure 3). The situation with slowest bud burst for higher and lower temperature under SD, compared to intermediate, was generally similar to in un-chilled plants (Figure 3). Also, like for un-chilled plants, the time to 50% bud burst in chilled plants increased with increasing temperature, but this relationship was most clear for the low NTs provided under SD. Generally, time to 50% bud burst decreased with increasing duration of chilling (Figure 4). Differences between provenances remained also after chilling; bud burst was earliest in the northernmost provenance P1 and latest in southernmost provenance F1 (Table 4).

Bottom Line: Although no specific effect of alternating DT/NT was found, the results demonstrate that the effects of DT under SD on bud set and subsequent bud break are significantly modified by NT in a complex way.The present results also indicate that low temperature during bud development had a larger effect on the most southern compared to the most northern provenance studied.In conclusion, being a highly temperature-dependent process, bud development is strongly delayed by low temperature, and the effects of DT is significantly modified by NT in a complex manner.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, Norwegian University of Life Sciences Ås, Norway.

ABSTRACT
Young seedlings of the conifer Norway spruce exhibit short day (SD)-induced cessation of apical growth and bud set. Although different, constant temperatures under SD are known to modulate timing of bud set and depth of dormancy with development of deeper dormancy under higher compared to lower temperature, systematic studies of effects of alternating day (DT) and night temperatures (NT) are limited. To shed light on this, seedlings of different provenances of Norway spruce were exposed to a wide range of DT-NT combinations during bud development, followed by transfer to forcing conditions of long days (LD) and 18°C, directly or after different periods of chilling. Although no specific effect of alternating DT/NT was found, the results demonstrate that the effects of DT under SD on bud set and subsequent bud break are significantly modified by NT in a complex way. The effects on bud break persisted after chilling. Since time to bud set correlated with the daily mean temperature under SD at DTs of 18 and 21°C, but not a DT of 15°C, time to bud set apparently also depend on the specific DT, implying that the effect of NT depends on the actual DT. Although higher temperature under SD generally results in later bud break after transfer to forcing conditions, the fastest bud flush was observed at intermediate NTs. This might be due to a bud break-hastening chilling effect of intermediate compared to higher temperatures, and delayed bud development to a stage where bud burst can occur, under lower temperatures. Also, time to bud burst in un-chilled seedlings decreased with increasing SD-duration, suggesting that bud development must reach a certain stage before the processes leading to bud burst are initiated. The present results also indicate that low temperature during bud development had a larger effect on the most southern compared to the most northern provenance studied. Decreasing time to bud burst was observed with increasing northern latitude of origin in un-chilled as well as chilled plants. In conclusion, being a highly temperature-dependent process, bud development is strongly delayed by low temperature, and the effects of DT is significantly modified by NT in a complex manner.

No MeSH data available.


Related in: MedlinePlus