Project Number: 2032-21000-024-11-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 17, 2018
End Date: Dec 31, 2019
The majority of pistachio rootstocks is currently produced from seed. The resulting F1 seedlings are genetically variable because of segregation in the gametes of each parent. This results in differences in morphology among individual rootstocks and in performance in the field. The UCB-1 hybrid is one of the main pistachio rootstocks used in the USA. It is produced from a controlled cross between specific clonal trees of Pistacia atlantica (female) x P. integerrima (male), and was selected for its resistance to Verticillium wilt, a serious soil pathogen of pistachio. Pistacia vera cultivars are grafted onto UCB-1 or other rootstock. Most pistachio production in the USA is in California and its farm gate value is about $2 billion during the “on” years (it is alternate bearing). Pistachio is very drought tolerant and grows naturally in dry climates. It has the most salt tolerance of any nut tree grown in the USA; therefore, growers plant pistachio on marginal lands or use waters of poor quality if soil or water salinity levels are too high for almonds or grapes. It has been reported that if the maximum root zone soil salinity is less than 10 dS/m, pistachio genotypes in Iran could be irrigated with saline water up to 8 dS/m. Others report that some pistachio orchards can grow well when irrigated with 3,000 – 4,000 ppm (4.7-6.3 dS/m) soluble salts. Differences in salt tolerance among UCB-1 seedlings is, however, unknown.
We propose to expand the UCB-1 replications of the current salinity study in Parlier to have more seedlings represented in the populations receiving the four different salinity treatments (<1, 4, 8, 12 dS/m). These trees will be thoroughly phenotyped with regard to growth and response to the treatments. The subcellular distribution of salt ions will be investigated in roots of selected rootstocks. DNA will be extracted from bark samples collected from the rootstocks of all treatment trees and their genomes will be sequenced to provide markers for genetic analysis. Molecular markers associated with salt tolerance/sensitivity will be identified. These can then be used in the future to both screen seedlings that will be planted in highly saline soils or irrigated with saline waters, and to select superior pistachio rootstock for clonal propagation.