Physiological and biochemical evolution of peach leaf buds during dormancy course under two contrasted temperature patterns

Abstract

Budbreak anomalies in temperate fruit trees grown under mild conditions have often been described. However, only few authors approached the physiological evolution of leaf buds all along the dormancy period according to the temperature pattern. The aim of this study was to characterize the evolution of peach leaf bud dormancy through some physiological and biochemical parameters under temperate winter conditions and under total cold deprivation after the endodormancy onset. Two treatments were applied in peach trees cv. Redhaven: (i) Regular Chilling Amounts — RCA and (ii) Total Chilling Deprivation — TCD. Buds were sampled periodically from different parts of the stem (terminal, medium and basal ones). We recorded the evolution of: carbohydrate concentrations (glucose, fructose, sucrose, sorbitol and starch), respiration rate, water contents and energy metabolism (ATP and ADP ratio). The dynamics of these parameters were compared and correlated with dormancy evolution ("one node cuttings" test) and budbreak patterns in plank:. The endodormancy intensity of terminal buds was significantly lower than those of median and basal buds in early October. Under RCA treatment, this gradient faded and the bud endodormancy release was completed at the same time in all positions along the stem. Thereafter, the "cuttings" test indicated that terminal buds grew slightly faster than median and basal buds, and, consistently, budbreak in planta started with the terminals buds, followed by the medians and then by the basal ones. The carbohydrate contents showed a transitory change only when the buds began to grow after the endodormancy was released under RCA. Respiration, water content and ATP/ADP changed dynamics only under RCA and only after the end of the endodormancy (their respective changes were very parallel). The dynamics of none of the tested parameters could be related with the endodormancy dynamics, but respiration, water content and ATP/ADP could be consistent markers of the actual bud growth before bud break (in this respect, ATP/ADP could not show differences between the terminal and axillary buds while respiration and water content could).

Induction and overcoming of dormancy of grapevine buds in response to thermal variations in the winter period

“…Budburst precocity and uniformity followed a similar response pattern with the evolution of endodormancy, not being affected by the thermal regime or cultivar (Figure 3). In the case of precocity, during the period of maximum endodormancy, the number of days to reach the budburst remained high, decreasing as the numbness was overcome (Figures 3A, 3B and 3C), a trend that was also observed by LEITE et al (2006) in peach, ALVAREZ et al (2018) in grapevine, andNAOR et al (2003) in apple trees. In case of uniformity, the budburst showed to be uneven during induction and full endodormancy, being synchronized after the latency period was over (Figures 3D,3E and 3F).…”

Chilling requirement of four peach cultivars estimated by changes in flower bud weights

“…The differences, even when statistically significant, were less than 10% (Table 3). The water content was associated with the plant dormancy state, in previous studies, in apple (Malagi et al, 2015;Sachet, 2013), peach (Leite et al, 2006;Bonhomme et al, 1997), and pear trees (Marafon et al, 2011;Simões et al, 2014). The percentage of water in the flower buds probably reveals the end of endodormancy and could be an alternative method for estimating it.…”