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These results indicate that phosphorus fertilizer application is necessary to
maximize nodulation of winter-planted chickpeas, whereas nitrogen fertilizer
appliation could adversely affect nodulation. Yield data are still to come and it
will be interesting to see whether the yield figures reflect the nodulation data,
Studies on Herbicides and Nodulation
The nodulation and nitrogen fixation in winter-planted chickpeas can be limited
by the presence of many weeds. In recent years, hand weeding has become less
economic in some countries of this region and chemical weed control may assume
greater importance. Herbicides can, however, affect the Rhizobiuni adversely.
The identification of tolerant strains will therefore be necessary. With this objective,
an experiment was conducted during '978-79 using five herbicides (Gesagard,
2 kg p/ha; Treflan, I liter p/ha; Alachlor, 3 liter p/ha; Metribuzine, I kg
p/ha; and Tribunil, 4kg p/ha) with winter-planted chickpeas (cv. ILC 1929) and
a mixed culture of three strains of Rhizobium for inoculation.
Metribuzine and Alachlor completely killed the plants. Of the other three
herbicides, only Tribunil gave agood control of weeds, without much affecting
plant growth and nodulation. Artificial inoculation partially removed the inhibitory
effects of herbicides on nodulation thus giving an indication that strains of
Rhizobium could be identified that might tolerate the herbicide and result in
better nodulation and grain production.
To study this aspect more thoroughly the performance of four strains of
Rhizobiuni (3889, IC-26, Cp-5b and Cp-37a) was evaluated on winter-planted
chickpeas (CV. ILC 1929) under Tribunil (4 kg p/ha) treatment during
1979-80. The results showed that the strains of Rhizobium differed considerably
in their tolerance to Tribunil as assessed in terms of nodulation. The strain 3889
performed the best under Tribunil treatment and produced sigificantly more
nodule mass compared with the hand weeded and inoculated treatments (Table
4). The effect is not reflected in grain yield because some of the plots were
affected by ascochyta blight at a later stage of growth and influenced grain
production considerably.
Conclusion
In the presence of effective Rhizobium strz.in, nodulation in winter-planted crop
isbetter than in the spring-planted crop. For the full realization of yield potential
of winter planting, it isnecessary to ensure that the appropriate strain of chickpea
Rhizobium is present in the rhizosphere, which can best be achieved by
artificial inoculation.