RA 00015.pdf - OAR@ICRISAT

days. Upon irrigation at 68 days, activity was
increased to 87 µ moles/plant per hour in both
treatments, and this pattern was repeated during
subsequent stress and irrigation periods. Stressed
plants produced less top and root growth and the
yield of 1 481 kg/ha was only half that of control
plants receiving regular irrigations.
Figure 49. Nitrogenase activity (µM C 2
H 4
/g
dry weight of nodule per hour) in
groundnut cultivar Kadiri 71-1, 81
days after planting, ICRISAT Center,
postrainy season 1976.
There were significant differences in nodulation
between the more than 400 germplasm
lines screened during the rainy and the postrainy
seasons. A few cultivars had much better than
average nodulation and a few were poorly nodulated.
During field surveys, nodulation was
noted to vary a great deal between locations and
soil types.
L o o k i n g A h e a d i n G r o u n d n u t
I m p r o v e m e n t
In the germplasm program we intend to develop
Jinks with the IBPGR to enable us to prepare a
set of descriptors and an acceptable international
groundnut classification system based on taxonomic
and agronomic characters. We expect to
have available shortly large quantities of germplasm
for cooperators; and we will be increasing
our own collection by additions from abroad.
Germplasm catalogs will be produced as soon as
possible.
As far as breeding goes, we hope to produce
through a large-scale crossing program highyielding
material with stable resistance to the
major pathogens. Other breeding objectives are
to incorporate earliness and dormancy with high
yield potential.
The virologists will continue their work on
characterizing and purifying the viruses under
current investigation. They will develop international
and regional arrangements for the survey
of all groundnut-growing areas to precisely
identify important viruses. Rapid germplasmscreening
techniques will be perfected to assist
breeding programs.
Efficient fungal-screening techniques for large
scale field testing of breeding populations with
resistance to leafspots and rust will receive
priority in the immediate future. For the major
foliage fungi, we hope to set up testing centers in
a number of countries to monitor stability of
resistance and to detect the development of
physiological races. We hope to develop rapid
methods of laboratory screening for the detection
of lines with resistance to invasion by
toxin-producing fungal strains, such as yellow
mold (Aspergillus flavus).
Planning for the entomology program is now
complete; it will get under way in late 1977.
Objectives of the program include survey of the
harmful and beneficial arthropods of groundnuts,
study of the vectors of diseases, and
assessment of the role of insects as pollinators in
groundnuts.
In microbiology, differences between lines in
nodulation and the interaction with Rhizobium
strain will be characterized to see if nitrogen
fixation increases with nodule number. Selected
lines with enhanced nitrogen-fixing activity will
be incorporated in a breeding program for
increased yield of total plant dry matter and
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