Effect of seed treatment on germination and emergence of 3 warm-season grasses.

Seed dormancy can hinder stand establishment and delay progress of genetic and plant improvement studies. Our objective was to evaluate the effect of 2 chemical seed treatments on germination and on emergence and survival of 3 warm-season grasses. Freshly harvested seed of kleingrass (Panicum coloratum L.) weeping lovegrass [Eragrostis curvula (Schrad.) Nees] and wilman lovegrass (Eragrostis superba Peyr.) were treated with concentrated H2SO4 or a 2-chloroethanol sodium hypochlorite (CHL) solution and then germinated on blotters or planted in a commercial peat-vermiculite mix. The 3 grasses responded differently to acid and CHL treatment. Acid treatment increased germination of all 3 species but did not increase the emergence and/or 2 week establishment of weeping or wilman lovegrass. The difference between germination and emergence appeared related to chemical injury from the acid treatment that adversely impacted seedling growth and development. Weeping lovegrass responded to CHL treatment with increased germination and emergence. Wilman lovegrass did not respond well to either chemical

Characterization of crown node elevation in Panicoid grasses.

In Panicoid grasses, elevation of the crown node above the soil surface caused by excessive subcoleoptile internode elongation is detrimental to seedling establishment. We describe a technique to screen grass seedlings for excessive crown node elevation. Seed of 11 perennial grass cultivars were germinated and grown in a plywood box 1.2 X 1.2 X 1.2 m at an irradiance of 1.5 micromole m(-2) sec(-1) at 30 degrees C. A subset of 8 grasses were grown similarly but at an irradiance of 0.75 micromole m(-2) sec(-1). Elevation of crown nodes above the growth media and shoot length (from crown node to leaf tip) were measured 7 days after planting. The crown nodes of 4 Eragrostis species were not elevated above the soil surface, while other species had mean crown node elevations of 1 cm or more. Relative ranking of crown node elevation was similar for a species within each light level, but response to change in light intensity was not consistent across species. Sideoats grama (Bouteloua curtipendula (Michx.) Torr.), blue grama (Bouteloua gracilis (H.B.K. Lag. ex Steud.)), and kleingrass (Panicum coloratum L.) exhibited significant crown node elevation in this system. Estimates of genetic variation based on comparison of apomictic and sexual grasses within this group suggest that substantial genetic variation exists for excessive subcoleoptile internode elongation and that progress by selection for lower crown node placement should be possible in most of the grasses studied. This system allows characterization of grasses for extent of crown node elevation and is being used in a recurrent selection protocol to select for lower crown node placement