The plant survival of three ecotypes of seashore paspalum (Paspalum vaginatum Swartz) submitted to freezing temperatures was evaluated by two methods: electrolyte leakage and freeze shock‐recovery. Bermudagrass [Cynodon dactylon (L.) Pets. cv. Midiron] was used as a check. Acclimated and nonacclimated plants were evaluated from 1994 to 1995 in Georgia by both methods to compare their performance. Results indicated that seashore paspalum was slower to acclimate than Midiron bermuda under the treatment conditions used in this experiment. However, a significant acclimation effect was found in HI‐1 paspalum, indicating the presence of variability for this trait within the species. The LT50 determinations demonstrated the superior cold hardiness of Midiron compared with seashore paspalum. Among the paspalum ecotypes, HI‐1 ranked superior to Adalayd and PI 299042, respectively, when plants were acclimated (AC). When nonacclimated (NA), Adalayd ranked superior to the other two ecotypes. These genotypic rankings were consistent for both methods of evaluation, indicating their effectiveness for efficiently screening cold hardiness responses among multiple ecotypes. Electrolyte leakage curves indicated that the lethal electrolyte leakage levels for AC and NA paspalum ecotypes were similar. Additional studies are required to evaluate the mechanism present in HI‐l, which showed significant acclimation effects on plant survival.

Paspalum vaginatum Swartz (seashore paspalum) is a warm season grass that can be used for turf, forage, erosion control, or bioremedialion. The species is a sexual diploid, but produces less than 5% viable seed, which poses problems for genetic enhancement by conventional breeding methods. The selection of somaclonal variants is one alternative methodf or genetic improvement. The objective of this study was to develop a standard tissue‐culture regeneration protocol for this species. Immaturein florescences of nine seashore paspalume cotypes were used as explants for the induction of embryogenic callus in two controlled laboratory experiments during 1993 to 1994 in Georgia. Five levels of (2,4‐dichlorophenoxy)acetic acid (2,4‐D; 0.0, 1.0, 2.0, 6.0 mg L−1) and three 6‐benzylaminopurine levels (BAP; 0.0,1.0, 2.0 mg L−1) were tested for callus induction during 1993 and four levels of 2,4‐D (2.0, 3.0, 6.0, 10.0 mg L−1) during 1994 in a factorial experiment with all treatment combinations. BAP effects were not significant for all ecotypes except Adalayd. The 2,4‐D response varied by ecotype, but all ecotypes responded to the lowest rate (1 mg L−1). significant embryogenic response was obtained in all ecotypes with 1 mg L−1 BAP in combination with 0.5 to 2.0 mg L−1 et‐naphthaleneacetic acid (NAA). HI‐1, Mauna Key, PI 299042, and K3 were highly embryogenic and PI 509021 and Adalayd were less embryogenic. High frequency plant regeneration of five ecotypes (PI 509021, HI‐1, Mauna Key, Adalayd, PI299042) was successfully achieved. The protocol from callus induction to plant regeneration for seashore paspalum has been streamlined to be effective and efficient.