The effects of temperature and drought on autumnal senescence and leaf shed in apple under warm, east mediterranean climate

Shaul Naschitz*, Amos Naor, Shmuel Wolf, Eliezer E. Goldschmidt

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Key message: Autumnal senescence of apple in a warm climate corresponds to accumulated degree-days beneath 22 °C. Summer drought delays senescence and enables replenishment of carbohydrate reserves. Recovery of the root system plays a key role. Autumnal senescence of apple (Malus domestica Borkh.), a deciduous, temperate climate species, is triggered by a rather abrupt temperature drop, down to the lower teens. Under the warmer, east Mediterranean climate of northern Israel, the temperature drop is gradual and much more moderate. Another characteristic of this climate is the complete lack of precipitation during summer. The aim of the present study was to elucidate the effects of summer drought on seasonal leaf senescence in a warm autumn. We hypothesized that summer drought delays senescence due to an increased demand for carbohydrates during autumn. The advent of autumnal senescence was followed for 3 years (2009-2011) on trees exposed to various levels of drought. Total canopy green area (effective leaf area, ELA) and hue angle were estimated periodically by means of image analysis, as a measure of leaf drop and autumnal color change. Photosynthesis, midday stem water potential, and roots' non-structural carbohydrate contents were measured on several occasions. The time course of leaf drop followed the decline in air and soil temperatures. The rate of decline in ELA closely corresponded to accumulated degree-days beneath 22 °C in the soil, a much higher temperature threshold than previously reported for apple. Drought stress during the summer delayed leaf senescence even further, when compared with well-irrigated trees. Leaves maintained their photosynthetic functionality throughout autumn, until late December. The delayed senescence enabled replenishment of root carbohydrate reserves, which is critical for next year's growth and fruiting. The eco-physiological significance of the findings is discussed.

Original languageAmerican English
Pages (from-to)879-890
Number of pages12
JournalTrees - Structure and Function
Issue number3
StatePublished - Jun 2014

Bibliographical note

Funding Information:
Acknowledgments We gratefully acknowledge the financial support by the Chief Scientist of the Israeli Ministry of Agriculture. We thank Jose Gruenzweig and Joseph Riov for reviewing the manuscript and Or Shapira, Carmel Biederman, Harel Agra, Moshe Agiv and Ami Kauffmann for their technical assistance.


  • Autumnal senescence
  • Drought
  • Malus domestica
  • Non-structural carbohydrates
  • Root system


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