Influence of environmental factors on germination and emergence of Pueraria lobata

Abstract

Laboratory and greenhouse studies were conducted to determine the effect of several environmental factors on seed germination and seedling emergence of the invasive weed Pueraria lobata (kudzu). Germination occurred over a range of alternating temperatures from 15/6 to 35/25 C. Seed germinated equally well in alternating light/darkness and continuous darkness. At all temperature regimes, percentage germination was much greater for hand-scarified seed (95 to 100%) than for nonscarified seed (7 to 17%), indicating that P. lobata seed possesses physical dormancy. Germination exceeded 51% in solutions with pH 5 to 9. Maximum germination (99%) was observed in distilled water at pH 5.4. Germination was greatly reduced in solutions with osmotic potentials below -0.4 MPa (28% at -0.6 MPa, and 13% at -0.9 MPa); no germination was observed at -1.3 MPa. Percentage emergence was greater than 45% at burial depths in soil of 0.5 to 10 cm, with maximal emergence (72 to 85%) at depths of 0.5 to 4 cm. Seed sown on the soil surface had low seedling emergence (< 13%). No seedlings emerged when seed was exposed to flooding for 7 d or more. Pueraria lobata seed is capable of germinating in a variety of climatic and edaphic conditions, but flooding may severely limit establishment of stands by seed.