Effects of scarification and cold stratification on seed germination of Lupinus sulphureus ssp kincaidii

Propagation methods for Lupinus sulphureus ssp. kincaidii, a threatened host plant for the endangered Fender's blue butterfly, are needed to support restoration efforts and ecological studies. Germination tests were performed to determine the effects of mechanical scarification and cold stratification (4 degreesC for 4 or 8 wk). Seeds from two populations were used to determine whether seed source affected germination. Scarification and stratification both increased germination, but germination rates were highest and fastest when these treatments were applied together. Maximum germination was 95% with seeds from one population, but only 55% from another, suggesting that germination responses differ among wild sources. To optimize germination speed and percentage, a combination of scarification and stratification should be used.