Interrelations between respiration and dormancy in buds of three hardwood species with different chilling requirements for dormancy release

Abstract

AbstractmRespiration in vegetative buds of mature Betula pendula, Alnus glutinosa and Prunus padus trees was measured monthly at 15°C from mid-October 1996 to natural outdoor budburst in April 1997. In B. pendula the effect of bud water content on respiration was also estimated (December±April) by artificial imbibition of buds for 24 h prior to measurement of respiration. For estimation of corresponding bud dormancy status, batches of twigs were forced at identical monthly intervals at 15°C in long days (24 h), and budburst recorded. In all species dormancy was deepest when the leaves were shed in October, and dormancy was first alleviated in P. padus followed by B. pendula and A. glutinosa. However, bud respiration capacity was not related to dormancy release as it decreased in all species from October to November and displayed no notable increase until February in P. padus, March in B. pendula and April in A. glutinosa, after completion of dormancy release. Rather, increase in respiration coincided with growth resumption prior to budburst. Artificial imbibition of B. pendula buds increased the water content by approximately 10% (FW) and induced a doubling of the respiration rate (December±February). Moreover, the seasonal variation in bud water content (October±April) explained 94% of the variation in respiration in B. pendula and P. padus, and 84% in A. glutinosa. These observations suggest an important role of water content for respiration. During a cold period from mid-December to mid-January with mean temperature of ±9.7°C dormancy release was arrested in P. padus, and to some degree in A. glutinosa, whereas dormancy release progressed normally in B. pendula. This indicates species differences in lower critical temperatures for dormancy release.

Bud dormancy breaking affects respiration and energy balance of bilberry shoots in the initial stage of growth

“…1). Similar results were obtained for Betula pendula, Alnus glutinosa, and Prunus padus [17]. On the branches of A. glutinosa placed in a controlled-climate chamber in November, the buds unfolded in 60 days, in March, they unfolded as early as in 10 days; the buds of P. padus opened in 25 and 5 days, respectively.…”

“…Low-temperature exposure of a certain duration is necessary for the buds of woody plants in the temperate zone. It prevents early initiation of growth in spring and shoot injury in case of return of cold weather [17]. Our investigations showed that a disturbance of biological rhythm of development as a result of artificial breaking of bud dormancy exerted a profound influence on the initial stage of extra-bud growth of bilberry shoots.…”

“…When the share of ineffective respiration decreased, sprouting buds could more efficiently utilize respiratory substrate for production of metabolic energy. According to literature data, bud respiration of deciduous woody plants goes down by autumn and greatly rises in spring upon dormancy release [17][18][19][20][21]. For instance, respiration rate of B. pendula buds in October-February remained very low and it grew more than ten times amounting in April to 1400 μL О 2 /(g dry wt h) [17].…”

“…According to literature data, bud respiration of deciduous woody plants goes down by autumn and greatly rises in spring upon dormancy release [17][18][19][20][21]. For instance, respiration rate of B. pendula buds in October-February remained very low and it grew more than ten times amounting in April to 1400 μL О 2 /(g dry wt h) [17]. For comparison, in May the rate of respiration of sprouting bilberry buds was approximately 4000 nmol О 2 /(g dry wt min) at 20°C (Table 1) or 5400 μL О 2 /(g dry wt h).…”

The Annual Phenological Cycle

“…3.12b) measures the increasing rate of ontogenetic development towards bud burst obtained with progressively longer durations of chilling. This rate, too, often evinces withinpopulation variation, but such variation is manifested as deviation from the mean DBB observed at any given duration of chilling rather than in the form of the DBB curve (Myking 1998). This variation is not shown in Fig.…”