Treatments to improve seed germination of Arnebia benthamii: an endangered medicinal herb of high altitude Himalaya

Methods for breaking dormancy and thereby improving germination of Arnebia benthamii (Wall. ex G.Don) Johnston, an endangered medicinal herb of the high altitude Himalayas were investigated. Seeds collected from two populations (alpine and subalpine) were subjected to various treatments, viz; cold stratification (chilling and chilling + gibberellic acid), plant growth substances (gibberellic acid, 6 benzylaminopurine and α Naphthaleneacetic acid) and nitrogenous compounds (thiourea and KNO₃). Both the populations differed significantly (p<0.001) in response to various pretreatments. In the alpine population, thiourea (50 mM) significantly (p<0.05) improved germination over that of the control (thiourea 96%; control 42%), whereas in the subalpine population chilling (14 d) resulted in a significant (p<0.05) improvement in germination over that of the control (chilling 14 d, 62%; control 13 %). Reasons for variation in the responses of the two populations and among treatments are discussed.