Nodulating behaviour of colchicine induced polyploids of Phaseolus aureus Roxb.

Abstract

Detailed morphology and nodulating behaviour of 2n, 3n and 4n Phaseolus aureus Roxb. were worked out. Tetraploids were gigas in nature when compared to that of the diploids; triploids were intermediate. Polyploidy was found to enhance root hair infection and induced early nodulation. Number of nodules on the tap root was maximum in case of tetraploids followed by triploids and diploids whereas it was reverse when the nodules on the lateral roots were considered. During the pre-flowering stage, total number of nodules increased with the increase in the ploidy levels of the hosts but it was reverse during flowering stage. Relative com-peting abilities of the Rhizobium strains for nodule sites were found to be affected by the polyploidy status of the hosts. Number and volume of nodules were found to bear significant correlations with the volumes of the roots (tap and/or lateral).