An Improvement in the Raggio Technique for Obtaining Nodules on Excised Roots of Phaseolus vulgaris L. in Culture

Abstract

Improvements are reported in the Raggio technique (e.g. Barrios, Raggio, and Raggio, 1963) for producing nodules on explants of roots excised from seedlings of Phaseolus vulgaris and grown in sterile culture. The principal modification is the inclusion of a portion of the hypocotyl in the explant. In a factorial experiment testing also seed size, germination temperature, and size of seedling at the time the explant was taken, the number of nodules formed was increased in this way from an average of 0·6 to around 12 per explant, and the largest number obtained was 35; without the piece of hypocotyl the largest number of nodules was 3 per explant.