Selection for productivity, persistence and drought tolerance in orchardgrass

This study was aimed to evaluate genetic diversity for drought tolerance and persistency of Iranian and foreign germplasm of orchardgrass. Thirty six genotypes of orchardgrass were clonally propagated and grown in the field under two moisture environments (normal and drought stress) for 3 years (2013–2015). High genotypic variation was observed among genotypes for all the measured traits, indicating a high potential for improving traits. Drought stress had negative effects on most of the measured traits and reduced genotypic variation. Low heritability for forage yield (average 21 %) suggested that indirect selection based on components of forage yield which had moderate to high heritabilities and high correlation with yield would be more effective. However, the order of priority of these components and their direct and indirect effects was different for normal and drought stress conditions. This suggested that indirect selection for development of high yielding drought-tolerant varieties should be performed under non-stress environment with a specific model. The results of principal component analysis showed that there was a negative relationship between phenological traits (days to ear emergence and days to anthesis) with the traits related to persistency and yield production. This indicates that selection for earliness in orchardgrass can improve productivity and persistency in orchardgrass. Contrasting genotypes were identified by biplot method that is useful for development of genetic populations for breeding studies of drought tolerance and persistency in orchardgrass.