Temperature Effects on Dormancy Completion of Vegetative Buds in Apple

Abstract

<jats:p>The relative contribution of various temperatures to dormancy completion of lateral vegetative apple [<jats:italic>Malus sylvestris</jats:italic> (L.) Mill. var. <jats:italic>domestica</jats:italic> (Borkh.) Mansf.] buds was studied quantitatively on whole container-grown trees. Trees were exposed continuously to 10 different temperatures and also to daily alternating temperatures in a 24-hour cycle. In addition, fully chilled vertically and horizontally positioned shoots were compared under forcing conditions. No budbreak occurred in shoots chilled above 12.5 °C. There was a steep increase in budbreak as the chilling temperature fell from 12.5 to 7.5 °C. There was little difference in the level of budbreak on shoots chilled between 7.5 and 0 °C. The relative contribution of temperature to chilling accumulation in apple found in our study differs from what has been proposed for stone fruit and for apple in previous studies, especially at temperatures &lt;6 °C. The length of exposure to forcing conditions required to initiate budbreak diminished as the chilling temperature was reduced. No additional bud-break was apparent on shoots chilled longer than 2100 chilling hours. The chilling requirement found here for lateral vegetative buds is much higher than that needed for terminal vegetative and flower buds. Trees that were exposed to daily alternating temperatures had lower levels of budbreak when the high temperature in the diurnal cycle was greater than 14 °C. Practically no budbreak was apparent on trees that were exposed to diurnal cycles with a high temperature of 20 °C for 8 hours. Budbreak on horizontally positioned trees was more than twice that on the vertically positioned trees, emphasizing the magnitude of the apical dominance effect and its strong masking of the chilling effect on lateral buds in vertically grown apple trees. Based on the data collected here we propose a new response curve for vegetative budbreak in `Golden Delicious·apple, within a temperature range between 0 to 15 °C.</jats:p>

Effects of shoot bending on ACC content, ethylene production, growth and flowering of bougainvillea

“…However, axillary buds generally developed close to the vegetative buds, and the vertical shoots became less mature than the horizontal and inclined shoots, and so had fewer flowering buds. These observations are consistent with those of Hampson et al (2004), Ito et al (1999), Meilan (1997), and Naor et al (2003). Inclined shoots of bougainvillea have more flowering buds and more fully blooming flowers, but their growth is slower because they contain more ACC than vertical shoots, and the ACC increases with the number of days of treatment.…”

Environment and position of first bud to break on apple shoots affects lateral outgrowth

“…In both warm and cool areas they will break before the vegetative buds which have a higher chilling requirement (Erez and Couvillon 1987;Naor et al 2003). This was evident in our study, and can explain the differences in BBP observed in the warm area, as all of the terminal BBP 'Granny Smith' axes were terminated by a reproductive bud while 87% of the lateral BBP axes were terminated by a vegetative bud (Table 4).…”

“…Reproductive buds have a lower chilling requirement than vegetative buds in both apple (Naor et al 2003) and peach (Erez and Couvillon 1987). In both warm and cool areas they will break before the vegetative buds which have a higher chilling requirement (Erez and Couvillon 1987;Naor et al 2003).…”

Transcriptional profiling of bud dormancy induction and release in oak by next-generation sequencing

“…firstly endodormancy: the deepest state of dormancy, in which bud burst is prevented by endogenous factors specific to the meristem. The strength of endodormancy increases from the end of summer, throughout the fall, generally peaking somewhere between the end of October and the end of November in the northern hemisphere depending on the species and the climatic conditions prevailing during the fall [4]. A dormancy breaking test, or forcing test, is the method of choice for assessing the depth of endodormancy in trees [5].…”