Abstract
The pistachio (Pistacia vera L.) industry in California is based largely on a single pistillate (i.e., nut-producing) cultivar (Kerman) supported by seedling rootstocks of P. atlantica Desf. Data were collected and analyzed for tree growth and productivity of 113 mature ‘Kerman’ trees/P. atlantica seedlings over two cycles of alternate bearing. Tree size as estimated by trunk cross-sectional area varied 4-fold among the trees analyzed; tree yields, averaged over 4 years, varied 8-fold within the plot, and cropping efficiency (yield/cm2 of trunk cross-sectional area) varied 3-fold among the trees within the orchard. The severity of alternate bearing also was calculated. Eight superior trees were identified within the orchard that not only had higher average yields and cropping efficiencies, but also exhibited much more regular cropping patterns (i.e., reduced severity of alternate bearing) than adjacent trees and the orchard as a whole.