Brief Exposure to Boiling Water Combined with Cold-moist Stratification Enhances Seed Germination of New Jersey Tea

Abstract

Although there is increasing interest in propagating prairie plants native to the midwestern United States for managed and natural landscapes, several species, including new jersey tea (Ceanothus americanus), are difficult to germinate from seeds. New jersey tea, which is an attractive, compact woody shrub, is found in high-quality prairie remnants throughout the tallgrass prairie region. Developing a protocol to increase the uniformity of seed germination in this species would allow for more widespread horticultural cultivation of this stress-resistant, nitrogen-fixing species. We hypothesized that the germination response of seeds of new jersey tea would be enhanced by replicating conditions that mimic their natural environment, which included treatments under controlled conditions exposing seeds to chilling temperatures, sulfuric acid, and boiling water. Two minutes of exposure to boiling water followed by 60 days of cold-moist stratification at 4 °C resulted in the highest germination percentage (48%) and mean daily germination (2.18 seeds/day). Scarification with 98% sulfuric acid for 15 min followed by 60 days of cold-moist stratification resulted in significant, but lower levels of germination percentage than seeds exposed to boiling water and cold-moist stratification. Cold-moist stratification in darkness and in an 18-hour photoperiod at 4 °C did not stimulate germination to a level suitable for production purposes. However, tetrazolium tests indicated that 79% of the seeds were viable. We conclude that cold-moist stratification should be used with boiling-water or acid-scarification to uniformly produce germinated seedlings of new jersey tea. However, nonresponsive seeds should not be discarded because they may germinate in later years if kept under appropriate conditions.