Predicting bloom dates by temperature mediated kinetics of carbohydrate metabolism in deciduous trees

Abstract

Trees in seasonal climates gauge winter progression to assure vital and productive blooming. However, how dormant plants asses environmental conditions remains obscure. We postulated that it involves the energetic reserves required for bloom, and therefore studied winter carbohydrate metabolism in deciduous trees. We quantified non-structural carbohydrates throughout winter in almond, peach, and pistachio trees in California and Israel and characterized winter metabolism. We constructed a carbohydrate-temperature (C-T) model that projects changes in starch and soluble carbohydrate concentrations by temperature mediated kinetics. Then, we tested the C-T model projections of bloom times by 20 years of temperature and phenology records from California. The C-T model attributes winter carbohydrate regulation in dormant trees to continuous updates of metabolic pathways. The model projects a surge in starch synthesis at the end of winter, and critically low concentrations of soluble carbohydrates, that trigger bloom. This is supported by field measurements of starch accumulation at the end of winter (˜50 mg g −1 DW in almonds) that preceded bloom by˜10 days. The C-T model provides a physiological framework for bloom forecasts in deciduous orchards. It integrates contrasting notions of chill and heat and elucidates why abnormal winter temperatures may compromise bloom in deciduous orchards.

Comparison of phenological traits, growth patterns, and seasonal dynamics of non-structural carbohydrate in Mediterranean tree crop species

“…4) as evidenced by the stable NSC pools in trunk throughout the year in walnut (Fig. 5) which are also reported in many studies and can be attributed to long-term storage that ensure survival during stress 10,29,32,34,[45][46][47][48][49] . (3) Avoid injuries as collecting cores can lead to stem splitting and fungi infections, as it is known to happen in walnut.…”

“…6), there was always increase in total NSC concentration in twigs that was either maintained (pistachio) or dropped to a lower level (almond, walnut) possibly due to mobilization for metabolism, translocation to roots 35,52 . This accumulation of NSC at leaf abscission is most likely associated with the storage of NSC to ensure winter survival 8,10,32,35,50 .…”

“…NSC storage has seasonal fluctuations marked by the alternation between a favorable season with positive net carbon balance and a dormancy season when trees rely solely on stored NSC 10,12 . Seasonal NSC fluctuation has been reported for trees from various phylogenetic groups (gymnosperms and angiosperms), life habits (deciduous, evergreen), and biomes (Boreal, Temperate, Mediterranean and Tropical) in natural conditions 29,[31][32][33][34][35][36][37] .…”

New indices for assessing changes in seasons and in timing characteristics of air temperature

“…Increases in global average temperatures have been welldocumented in the literature, but other characteristics of temperature, like regional and seasonal variability or timing, have been less well studied (Allen and Sheridan 2016;Rogers 2013;Trenberth 1983). Among the different thermal characteristics of climate change, timing is an important issue for many bio-climatological processes, as, e.g., earlier onset of spring/summer or delayed onset of autumn and shortening of winter can have impacts on flowering dates (Sperling et al 2019;Woznicki et al 2019), migratory species (Fraser et al 2019;Helm et al 2019;Schmaljohann 2019), and human adaptation to extreme temperature environments. In this work, we developed a new configuration of the seasons in order to quantify changes in timing in thermal climate characteristics.…”

Development of Peach Flower Buds under Low Winter Chilling Conditions

“…An excessive fruit load in the previous season may affect the C/N relationship, reducing plant reserves, especially in late-ripening cultivars in which the maturation of fruits coincides with flower induction. It can even cause competition among organs for carbohydrates, since final fruit growth immediately precedes flower bud initiation, which is a factor contributing to alternate production in unmanaged fruit trees [91][92][93][94][95][96][97].…”