RA 00015.pdf - OAR@ICRISAT

Figure 36. A promising row of chickpea in the breeding nursery where disease losses are heavy, as
evidenced by blank areas in the field.
these verified as Rhizobium. There are large
differences among these strains in nodulation
and nitrogen fixation, and field-inoculation trials
indicate an interaction among strain, soil type,
and host cultivar. When chickpea Rhizobium is
absent from the soil, seed inoculation produces a
marked zonation of nodulation, with nodules
forming on, or close to, the primary root in a
band from the seed to 12 to 15 cm below it. In
soils containing chickpea Rhizobium populations,
nodules form initially on the primary
root, but then also form on the secondary roots.
Nodulation and Nitrogen Fixation
Large areas of chickpea are sown following rice.
At ICRISAT Center, chickpea after rice responded
to inoculation with an increase in
nodulation, nitrogen fixation, and a 64-percent
increase in grain yield (Table 37). Uninoculated
plants formed virtually no nodules. Inoculated
plots yielded 1 800 kg/ha, as did plots given a
large application of N fertilizer, indicating that
N 2 fixation by nodulated plants was adequate.
Five cultivars of different duration were compared
at ICRISAT Center. At only 17 days after
sowing, there were differences in nodule number
per plant. Nodule number and nodule weight per
plant, as well as nitrogenase activity measured by
acetylene reduction assay, increased up to the
61st day but declined by the 81st day due to
nodule senescence. Nodule weight per plant
101