Pistachio Salinity Studies
University of California
Pistachio Salinity Studies

Current Research Direction

Louise Ferguson, Blake Sanden & Craig Kallsen

Much remains to be learned regarding the mechanisms of salinity and ion, particularly sodium, tolerance in pistachios. The work of our team members, and others, over the last 30 years, suggests that the genus Pistacia is the second most tolerant tree species, after date palms. However, this combined work did not investigate the mechanisms of this salinity tolerance; how salts are excluded, taken up or sequestered in the plant. Or how to enhance or adapt these characteristics for better salinity tolerance.

The roots play a pivotal role in salinity tolerance. For this reason, we have elected to focus future research in these areas:

I. Examining the relationships among soil and tree tissue Na, and the extensive freeze damage observed during 2009/2010. During this time period, young pistachios died or had severely restricted spring growth in saline/sodic “hot spots” in some SJV orchards. Symptoms appear the same as frost damage and have generally been located in a lower part of the field.  However, some adjacent trees appear to have no symptoms.
Blake Sanden, Principal Investigator
Craig Kallsen & Louise Ferguson, Co-Principal Investigators

Objectives:

  • Characterize salinity gradient from “bad” to “good” areas.
  • Correlate lab data with inexpensive field techniques to determine total salinity/water-logging.
  • Correlate tree wood samples (drilled cores) with Na levels/damage/above data.
  • Determine the salinity/sodium/water-logging threshold leading to mild frost susceptibility.

II. Characterizing and determining the mechanism of salinity tolerance in the currently available pistachio rootstocks.
Louise Ferguson, Principal Investigator
Blake Sanden & Craig Kallsen, Co-Principal Investigators

Objectives:

  • Investigate the three physiological processes influencing salt transport to the shoot: (in major rootstocks).
  • Selectivity of uptake from the soil solution at the root cortex.
  • Loading of the xylem.
  • Retrieval from the xylem in upper parts of the roots.
  • Determine if control in the shoot occurs by the exclusion of salt from the phloem sap flowing to the shoot.
  • Determine how the relative growth rate of the Kerman scion on the major different rootstocks affects the salinity status of the scion.
  • Determine if cellular sequestering of salts in the vacuoles of leaf mesophyll cells is occurring in the scion

III. For the long term, using this information to improve the salinity tolerance of pistachio rootstocks.
Louise Ferguson, Blake Sanden & Craig Kallsen

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