Inheritance of salt-tolerance traits among Kentucky bluegrass hybrids

Kentucky bluegrass (Poa pratensis L.) is widely used because of its adaptation to recreational spaces in the Intermountain West and elsewhere. It is considered salt sensitive and therefore is a good candidate for breeding improvement for this trait. However, improvement in Kentucky bluegrass is difficult because of apomictic reproduction and dosage effects from high polyploidy. The objective of this study was to evaluate salinity tolerance of Kentucky bluegrass hybrids and their parental lines and identify those with above mid-parent trait values for salt tolerance to identify lines for future breeding. Fifteen hybrid progeny from five paired crosses were previously identified, their apomictic offtype characterized with flow cytometry, and their turf quality (TQ) and electrolyte leakage (EL) traits measured over time and under salt treatment. There was significant variation in salinity tolerance among the different parents and hybrids, with most hybrids showing trait values between the two parents. The salt-tolerant parents PI440603 and PI371768 produced hybrids with greater than mid-parent tolerance when crossed with elite Kentucky bluegrass cultivars. Seven hybrids [('Washington' x PI440603)-3 and -5, (PI499557 x PI440603)-1 and -2, (PI578827 x PI371768)-1 and -2, and ('North Star' x PI371768)-1] had above mid-parent averages, significantly better TQ and EL than their respective salt-sensitive parent, or the smallest change in TQ or EL values between control and salt-treated plants.