Germination Requirements of Key Southwestern Woody Riparian Species

Abstract

Germination requirements of selected Southwestern woody riparian species were studied in the laboratory. Four common tree species selected for study were Fremont Cottonwood (Populus fremontii), Goodding Willow (Salix gooddingii), Arizona Sycamore (Platanus wrightii) and Velvet Mesquite (Prosopis velutina). Seeds were collected from two major riparian habitats in the southwest. The species tested required a temperature range of 16° C to 27° C for germination. Fremont Cottonwood, Goodding Willow and Velvet Mesquite showed good germination at moisture stress levels of -4 bars or less, whereas Arizona Sycamore only germinated well at 0 bars. For all species tested, germination was better at salinity levels lower than 50 meq /liter NaCl. All species displayed successful germination responses between pH 5 to 7. Velvet Mesquite germinated at all pH levels (5 -10). Longevity of seeds of riparian species is reported to be of short duration. This was confirmed in these studies with southwestern woody riparian species.