Endogenous ethylene does not initiate but may modify geobending–A role for ethylene in autotropism

Abstract. Ethylene production during geostimulation was examined in peduncles of dandelion ( Taraxacum officinale ). Significant amounts of ethylene were evolved from geostimulated peduncles compared with vertical controls only after geostimulation of 2 h or longer and the extra ethylene arose mainly from the lower portion of geostimulated peduncles. Reduction of the ethylene produced from geostimulated peduncles by pretreatment with ethylene‐synthesis inhibitors did not affect or enhanced subsequent geobending. It is proposed that ethylene may control the later stages of geobending and influence the straightening process of autotropism.