Inheritance and combining ability of persistence and drought recovery in smooth bromegrass (Bromus inermis L.)

Abstract

Post-drought recovery, persistence and summer dormancy in smooth bromegrass (Bromus inermis L.) genotypes and the inheritance of these traits as affected by different prolonged water management regimes are very poorly understood. In this study, we evaluated first-generation half-sib families derived from the polycross of parental genotypes for phenological, agronomic and morphological traits in the field for 4 years (2011–2014) under normal and deficit irrigation regimes. In the fifth year (2015), we first withheld irrigation in both treatment regimes for 2 months, and then after re-watering we evaluated the post-drought recovery of the genotypes. We found that additive gene action alone played an important role in controlling most of the traits, but that both additive and non-additive gene effects played a role in the genetic control of forage yield. Post-drought recovery was positively correlated with previously measured morphological traits, establishment rate and spring growth, suggesting that recovery potential can be predicted through developing an index. The stability analysis on general combining ability and the principal component analysis clearly identified the superior and stable genotypes able to transmit both stability and high plant productivity to their progenies.