Development of Range Grass Seedlings Germinated in Picloram

Abstract

Picloram (4-amino-3,5,6-trichloropicolinic acid) did not influence germination but differentially regulated postgermination growth of range grass seedlings. Radicle elongation of buffalograss(Buchloe dactyloides[Nutt] Elgelm.), sideoats grama(Bouteloua curtipendula[Michx.] Torr.)3, and switchgrass(Panicum virgatumL.) in petri dishes was reduced by 125 ppb picloram, whereas shoot elongation was not retarded by 1,000 ppb. Buffalograss, sideoats grama, and switchgrass seedlings, germinated in soil containing 500 ppb picloram, were usually not reduced in topgrowth production. However, topgrowth production of Arizona cottontop(Digitaria californica[Benth.] Henr.) and vine mesquite(Panicum obtusumH. B. K.) was reduced by 125 to 250 ppb of picloram in soil. Relative tolerance to picloram was ranked buffalograss, sideoats grama>switchgrass>vine mesquite, Arizona cottontop.