GENETIC-VARIATION FOR EPICUTICULAR WAX PRODUCTION IN ALTAI WILDRYE POPULATIONS THAT DIFFER IN GLAUCOUSNESS

Epicuticular wax (EW) is reported to be a beneficial trait for the adaptation of plants to water-limited environments. Glaucousness is associated with increased EW in other species and with a forage yield advantage in Altai wildrye [Leymus angustus (Trin.) Pilger Dewey] grown in a water-limited environment. The purpose of this research was to determine the variation for EW production, the heritability of EW production, and genetic correlation of EW production with forage yield within three populations of half-sib lines of Altai wildrye that were glaucous, nonglaucous, or variably glaucous (unselected). Leaf EW was extracted with petroleum ether and expressed as mass per unit leaf area (EW1, g m-2) or as mass per unit leaf dry weight (EW2, mg g-1). The glaucous population produced about twice as much EW as the non-glaucous and unselected populations in each of 3 yr. The variation among half-sib lines for both EW1 and EW2 within each population was significant. The distribution of the glaucous population was distinct from the other two populations in all 3 yr. Heritability estimates for EW1 were 0.36 (SE = 0.12), 0.90 (SE = 0.17), and 0.67 (SE = 0.15) for the glaucous, unselected, and nonglaucous population, respectively. Heritability estimates for EW2 were in the same range. The genetic correlations between EW production and forage yield were significant for the glaucous population (r = -0.25* for EW1, r = -0.53** for EW2) and the nonglaucous population (r = -0.31* for EW2). While selection for increased EW production is feasible for Altai wildrye, it would result in lower forage yield in water-limited environments.