Germination and Early Seedling Growth of Chaffy‐Seeded Grasses at Negative Water Potentials

Abstract

Drought is the most frequent cause of stand establishment failure of native grasses. An experiment was conducted to determine the interactions of seed processing and simulated dry conditions on seed germination and seedling growth of five chaffy‐seeded, warm‐season grasses. Seed of big bluestem (Andropogon gerardii Vitman), sand bluestem (Andropogon hallii Hack.), little bluestem [Schizachyrium scoparium (Michx.) Nash], yellow bluestem [Bothriochloa ischaemum (L.) Keng. var. ischaemum (Hack.) Celarier and Harlan], and indiangrass [Sorghastrum nutans (L.) Nash] were processed into intact spikelets‐chaffy pure‐seeds, debearded spikelets‐chaffy pure‐seeds lightly trimmed of hair and awns, and caryopses. Fifty‐seed samples of each species and seed form were germinated at water potentials of –1.6, –0.8, –0.4–0.2, and 0 MPa for a 21‐d period. There were species × water potential and species × seed form interactions for 7‐d germination, 21‐d germination, and potential maximum germination, and for seedling root and shoot lengths. In general, seed germination and seedling growth were reduced as the water deficit potentials increased. Germination was slower and much lower from intact and debearded spikelets compared with caryopses. The slower germination of intact and debearded spikelets also resulted in shorter root and shoot lengths when compared with caryopses. Given the amount of genetic variation within most cross‐pollinated species, this procedure could be used as an effective selection tool for breeding cultivars with improved germination and seedling growth at low water potentials.