Investigating Physiology of Salt Processing in Pistachio

Soil salinity in California’s San Joaquin Valley may be developing into a limiting factor in the performance of even the most saline tolerant of the region’s tree crops: pistachios. Differences in the salinity tolerance of diverse rootstocks have motivated investigation of the biological mechanisms that lead to these differences, and whether or not a rootstock’s response to salt (here, NaCl) offers some protection to the scion. We begin this investigation of whole tree salt management in pistachios by looking at two potential levels of tolerance: 1) Na+ retrieval from xylem sap as a varying mechanism of salinity tolerance in pistachios across rootstock-scion combinations; and 2) phloem recycling and sequestration of Na+ as a varying mechanism of salinity tolerance in pistachios across rootstock-scion combinations. Our material is unbudded, self-budded and P. vera ‘Kerman’-budded P. integerrima, and P. ‘UCB1’ (P. atlantica x P. integerrima) rootstocks. This work may help explain the contributions of rootstocks to scion Na+ tolerance, information valuable to the industry for its potential application to water management and breeding.