- Author: Jeannette Warnert
The UCCE citrus and pistachio crops advisor in Kern County, Craig Kallsen, is the UC Cooperative Extension Presidential Chair for Tree Nut Genetics, and UCCE integrated orchard management specialist Bruce Lampinen, based at UC Davis, is the UC Cooperative Extension Presidential Chair for Tree Nut Soil Science and Plant Water Relations. The endowed chairs will give the two scientists a dedicated source of funding for five years, when the chairs are reopened for review.
UC ANR established the two $1 million endowments for the endowed chairs last year. Half the funding was provided by UC President Janet Napolitano; the other half was donated by the California Pistachio Research Board. Establishment of the endowed chairs was announced last year by UC ANR vice president Glenda Humiston.
“I'm pleased that we have identified two exceptional research programs to support with the first endowed chairs in the more than 100-year history of UC Cooperative Extension,” Humiston said. “I feel certain Craig and Bruce will make significant advances in pistachio production systems under California conditions.”
Pistachio breeding program
Kallsen said the endowment comes at a particularly opportune time for the UC pistachio breeding research program. In cooperation with UC Davis pomology researcher Dan Parfitt, Kallsen has been breeding pistachios as part of a variety selection program using conventional methods - manually crossing and then growing trees to determine whether they have beneficial characteristics.
“Breeding new varieties this way takes a while, especially in pistachios,” Kallsen said. “They don't bloom for four or five years. With some trials we are just now at the stage where it gets interesting. The funding will be helpful for evaluating the new progeny.”
Kallsen is looking for pistachio varieties that show novel nut, tree growth and yield characteristics, and for varieties that produce a high yield even under low-chill conditions.
“The climate appears to be warming,” Kallsen said. “That poses a problem for pistachios, because our current cultivars have a significant chilling requirement that has not always been met when we don't have cold, foggy winters.”
Kallsen plans to establish a trial pistachio orchard at the UC Riverside Coachella Valley Agricultural Research Station, where winter weather rarely dips to sufficient chill levels, to see which varieties produce acceptable crops under the warmer conditions.
Another key objective of the UC breeding program is identifying pistachio cultivars that mature at different times. At the moment, 90 percent of California pistachios are the Kerman variety. They all mature at the same time, putting pressure on harvesting, transportation, processing and storage resources.
“Ten years ago, UC introduced the Golden Hills variety, which matures about two weeks earlier. It now represents 5 or 10 percent of the state's crop,” Kallsen said. “We're looking closely at another potential cultivar that matures 10 days before Golden Hills.”
Pistachio research at UC Davis
Lampinen has devoted most of his career to almond and walnut research, but has worked on pistachios in collaboration with other UCCE specialists and advisors since 2009, focusing mainly on canopy light interception and salinity and their impacts on pistachio yield and water use.
Lampinen said his current work on almond and walnut water use as related to canopy size will be expanded to pistachio with the funding from the endowment.
“Some preliminary data on this is currently being gathered, but there is a need to expand this work to a wider range of orchard ages and planting configurations,” Lampinen said. “It will be very useful to have the ongoing support from an endowment.”
Lampinen's work in almonds and walnuts will also inform new pistachio research approaches. For example, Lampinen developed a no-pruning system for establishing new walnut orchards, and will study whether a similar approach in pistachio would make sense. For decades, California farmers believed that pruning young walnut trees was critical to healthy tree development. Lampinen observed unpruned walnut orchards in France, and “they looked perfectly fine,” he said.
Lampinen's research showed that pruning in the early years of tree development reduced water use efficiency and decreased walnut yields. By not pruning young trees, farmers could cut back significantly on labor costs and eliminate the need to dispose of the vegetation cut off the tree while using water more efficiently.
The no-pruning approach is now widely accepted in almonds and walnuts. With funding from the five-year endowment, he plans to compare the impacts of the alternative pruning systems on newly established pistachio orchards.
In addition, Lampinen said he plans to consult with pistachio industry leaders, growers and farm advisors to develop an effective research program on pistachio soil and water relations.