Germination Control of Johnsongrass Rhizome Buds

Abstract

Field-harvested johnsongrass (Sorghum halepense(L.) Pers.) rhizomes were assayed for bud dormancy and growth potential under a number of experimental conditions. Natural dormancy was not detected in single-node rhizome pieces harvested at any time of the year. Shoot growth rates were highly variable. Kinetin, benzyl adenine, gibberellic acid, and 2-chloroethylphosphonic acid were ineffective in enhancing germination or normalizing shoot growth. Scale leaves of rhizomes had no effect on bud growth. Rhizome buds were strongly influenced by apical dominance and emerged shoots partially suppressed germination of adjacent buds. The optimum temperature for bud germination and shoot growth was approximately 30 C. Bud germination was suppressed at 15 C. Johnsongrass rhizomes failed to exhibit cold hardiness at any time in their life cycle.