Investigation of Seed Treatments and Fertilizer on Growth of Penstemon tubaeflorus


Jenna Annis

Additional Authors:

Jennifer O’Brien, Janice Coons, Nancy Coutant, Juston Curry


Sept 2014


Fertilizer, hickory smoke and ash, Scrophulariaceae, seed germination, stratification, tallgrass prairie restoration, transplants.

ABSTRACT Penstemon tubaeflorus is a North American prairie forb of conservation concern. Protocols for seed germination and transplant production involving fertilization are needed for conservation purposes. Our objectives were to compare techniques for breaking seed dormancy and increasing germination, and to investigate fertilizer on growth of Penstemon tubaeflorus. Seed treatments were hickory smoke seasoning solution (1:10, 1:100, 1:500, and 1:1,000), light vs. dark, prairie plant ash solution (2, 4, 8, and 16 g/L), and cold moist stratification (1 or 2 mo at 48C). Seeds were germinated in Petri dishes in germination chambers and counted for 21 d. For hickory solutions, 1:100 had the highest germination (51%), and seeds germinated in light, but not in the dark. For ash solutions, 8 g/L (6%) and control (4%) germinations were higher than 2 g/L with 4 g/L and 16 g/L being intermediate. Germination increased for both stratification durations (37%) compared to control (2%). For fertilizer studies, seeds were planted in soilless mix with no fertilizer, liquid fertilizer (20–20–20 at 1.25 g/L water), or solid fertilizer (14–14–14 slow release at 14.6 g/L mix) in growth chambers. After 7 wk, shoot fresh mass, leaf number, leaf area, crown diameter, root length, and shoot dry mass were measured. Seedling growth was greatest with solid fertilizer compared to control and liquid fertilizer, which were similar. Overall, hickory solution at 1:100 with light produced the highest percent germination among all treatments, and solid fertilizer was most effective for transplant development. These findings are useful for management or restoration of P. tubaeflorus populations.