Cultural and Biochemical Characteristics of Root Nodule Bacteria of Chickpea (Cicer arietinum L.)

Abstract

Summary The study on cultural and biochemical characteristics of 115 strains of root nodule bacteria of chickpea (henceforth named Cicer-Rhizobium ), suggest that only few characteristics, like the absence of growth on yeast extract mannitol agar (YEMA) in 24 h, no or little growth on glucose peptone agar without change of p H of the medium in 48 h, inability to produce 3-ketolactose, to precipitate calcium glycero-phosphate, to form serum zone coupled with acid production in litmus milk, to tolerate 20 meq Mn ++ /1 lactose medium and p H 10.0 in Hofer's alkaline broth, could be of diagnostic value in the identification of Rhizobium . In other characteristics, the strains were found to vary. The Congo-red colour differentiation was better obtained by pour plate method than by streaking the culture on YEMA plates. The production of acid or alkali on mannitol was found to be independent of the properties of soil from where the strains were isolated; and this did not substantiate Norris's hypothesis that Rhizobium , associated with tropical legumes, produces alkali. The position of Cicer-Rhizobium as a link between the group of fast growing Rhizobium from clover, pea, and beans and the slow growing group of Rhizobium from soybean, lupin, and cowpea miscellany has been indicated.