Stratification, freezing, and drying effects on germination and seedling growth of Altai wildrye

Abstract

Altai wildrye (Leymus angustus (Trin.) Pilger) is recommended for late season forage and stabilization or improvement of salt affected land in the northern Great Plains. Establishment from seeding is erratic, perhaps due to environmental extremes that occur in the seedbed. Objectives of this study were to evaluate the effect of temperature and moisture variation on germination, solute leakage from seeds, and etiolated growth of seedlings of this perennial grass. Seeds were subjected to 5 preincubation treatments: stratification (5 degrees C) (STR); stratification plus drying (30 degrees C) (STR-D); stratification plus freezing (-10 degrees C) (STR-FR); cool-dry storage (5 degrees C) (COOL); and laboratory storage (LAB). After pretreatment, seeds were incubated at 10 and 20 degrees C in a gradient of osmotic potentials ranging from 0.0 to -1.59 MPa. Solute leakage from seeds and seedling growth were also assessed following pretreatment. Germination was higher and more rapid over the range of osmotic potentials at 20 degrees C than at 10 degrees C with germination poorest in STR-FR. In the absence of water stress, leakage of solutes was 21% lower from stratified seeds than unstratified seeds; leakage at -0.48 MPa was similar across pretreatments. Compared to the other pretreatments, root and shoot growth of seedlings following STR-FR were reduced 34 and 76% at -0.48 MPa. Negative effects of STR-FR were reflected in restricted germination and growth, but not in solute leakage. Results of this study and others suggest that efforts to minimize temperature extremes in the seedbed could improve germination and seedling growth of Altai wildrye.