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Well-watered citrus tested in cold-acclimating temperatures

January 31, 2014
American Society for Horticultural Science
Researchers studied well-watered citrus to determine changes in water relations during cold acclimation, independent of drought stress. Potted sweet orange and Satsuma mandarin trees were exposed to progressively lower, non-freezing temperatures to promote cold acclimation. Results indicated that water relations of citrus during cold acclimation vary from those known to occur as a result of drought stress. The results could challenge traditional measures of plant water status in irrigation scheduling during winter.

Commercial citrus growers are often challenged by environmental conditions in winter, including low seasonal rainfall that is typical in many citrus growing regions. Growers must rely on irrigation to sustain citrus crops through dry winters, so understanding how to determine citrus irrigation needs is critical for successful operations.

Authors of a study published in HortScience noted that current methods used to determine moisture needs for citrus are limited, in that they do not account for effects of cold acclimation on water requirements. "Evidence suggests that at least some changes in plant water deficits occur as a result of cold temperatures and not dry soil," noted Robert Ebel, lead author of the study. "Changes in citrus water relations during cold acclimation and independent of soil moisture content are not well understood. Our study was conducted to characterize changes in plant relations of citrus plants with soil moisture carefully maintained at high levels to minimize drought stress."

Ebel and his colleagues conducted two experiments--the first in Immokalee, Florida, using potted sweet orange, and the second in Auburn, Alabama, using Satsuma mandarin trees. The citrus plants were exposed to progressively lower, non-freezing temperatures for 9 weeks. During the experiments trees were watered twice daily--three times on the days data were collected--to minimize drought stress.

Results of the experiments showed that soil moisture was higher for plants in the cold compared to plants in the warm chamber, and results showed that cold temperatures promoted stomatal closure, higher root resistance, lower stem water potential, lower transpiration, and lower stem water potential. Leaf relative water content was not different for cold-acclimated trees compared with the control trees. The key to minimizing drought stress, the scientists found, was carefully maintaining high soil moisture contents throughout the experiments, especially on the days that the measurements were performed.

"Our modern understanding of plant water relations has mainly evolved from studying growing plants at warm temperatures and in soils of varying moisture contents," Ebel explained. "However, this study demonstrates that those relationships are not consistent for citrus trees exposed to cold-acclimating temperatures."

The authors added that the study findings could have implications for commercial citrus growers who currently use traditional measures of determining irrigation scheduling during winter months.

The complete study and abstract are available on the ASHS HortScience electronic journal web site:

Story Source:

Materials provided by American Society for Horticultural Science. Note: Content may be edited for style and length.

Journal Reference:

  1. Smita Barkataky, Robert C. Ebel And Kelly T. Morgan. Water Relations of Well-watered Citrus Exposed to Cold-acclimating Temperatures. HortScience, October 2013

Cite This Page:

American Society for Horticultural Science. "Well-watered citrus tested in cold-acclimating temperatures." ScienceDaily. ScienceDaily, 31 January 2014. <>.
American Society for Horticultural Science. (2014, January 31). Well-watered citrus tested in cold-acclimating temperatures. ScienceDaily. Retrieved April 22, 2024 from
American Society for Horticultural Science. "Well-watered citrus tested in cold-acclimating temperatures." ScienceDaily. (accessed April 22, 2024).

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