Correlation between profile of ion‐current circulation and root development

The electrical currents associated with developing primary root tips ofTriticum aestivumL. cv. Slejpner,Avena sativaL. cv. Victory I,Lolium perenneL. cv. Melle,Vigna radiata(L.) Wilczek,Arachis hypogaeaL.,Pisum sativumL. cv. Keluedon Wonder,Lonchocarpus leucanthusBurk,Dalbergia nigraFr. Allen andPicea abies(L.) Karst. (U. K. Forestry Commission Number: 85/498/B). and that of the adventitious root tips ofFragaria vescaL.,Solanum tuberosumL. cv. Maris Piper andNeptunia plenaLindl. were examined with a vibrating electrode. Current was found consistently to enter the meristematic and elongating tissues of all the intact growing roots examined. Mature non‐growing root regions were responsible for generating the outword limb of the current loop. Peak inward current densities ranged between 2 mA m−2(Lolium) and 28 mA m−2(Arachis). The point at which the inward current reversed to outward current also varied between species. These results, which are derived from 5 taxonomically diverse families (Graminae, Leguminosae, Rosaceae, Solanaceae and Pinaceae) extend the range of different species that have been shown to generate ion currents that transverse, in a highly polar manner, the growing regions of their root systems. This supports the correlations between endogenous current generation and root development.