Sorghum Diseases in India

terization of the lines for important traits, easy
access to seed is still a problem. Quarantine restrictions
on seed entry into many countries is of
course mandatory, but such restrictions certainly
complicate easy and timely transfer of germplasm.
Many collections made by various individuals
or groups are not sent to ICRISAT or
even to the germplasm repository within their
own country. Thus parts and bits of various collections
exist in locations throughout the world.
United States Department of Agriculture's
National Germplasm System is making a concerted
effort to enhance the use of germplasm,
both in short and long term, within the country.
The system includes the National Seed Storage
Laboratory, Fort Collins, Colorado; the Regional
Plant Introduction Station at Griffin, Georgia;
and the GRIN system. GRIN, a database system
to catalog all sorghum introductions in the USA,
contains descriptive information and the known
ratings of important traits for each accession.
The information is available to anyone.
Closer cooperation between the U.S. National
Germplasm System and the ICRISAT Germplasm
Unit is encouraged. Additional collections
are needed from certain areas of the world.
Also needed are consolidation, cataloging, classification,
and gathering of data on useful traits
on material in the many collections now maintained
in various locations.
Assembling seed and information into central
repositories for long-term storage, maintenance,
and source seed is an urgent need. Many
landrace varieties from tropical areas are tall and
photoperiod sensitive, and thus too late for effective
use in temperate regions. The cooperative
Texas A&M, Texas Agricultural Experiment
Station, and USDA/ARS Sorghum Conversion
Program converts tall, photoperiod sensitive, exotic
lines to shorter, early (nonphotoperiod sensitive)
lines for use by all sorghum improvement
programs, public or private, worldwide. The
program utilizes short winter days in Puerto
Rico for making crosses and backcrosses, with
selection for short, early plants during long
summer days in Texas. After four backcrosses,
most converted lines are sufficiently similar to
the original exotics and are increased and released
as converted versions of the original
lines, with a "C" added to the original IS number.
To date, 423 fully converted lines have been
released. A total of 1385 lines have been entered
into the Conversion Program. New items en­
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tered in the past few years include selected
Zera-zeras from Ethiopia, selected Guineaense
lines from western Africa, lines from sandy, very
low rainfall zones of Sudan and Niger, and selected
individual lines with specific traits identified
by sorghum researchers throughout the
world. Sorghum workers from around the world
are encouraged to suggest sorghums with elite
trait(s) that should be converted.
The conversion project is very effective in
providing new, diverse germplasm with useful
traits in useful form to sorghum workers. In
USA, most of the best currently used and widely
adapted sources of resistance to head smut,
downy mildew, anthracnose, grain mold/weathering,
charcoal rot, midge, lodging, and staygreen
trait (postflowering drought tolerance) are
materials from the Sorghum Conversion
Program.
A conversion program to change the height
and maturity of pearl millet, using procedures
similar to those effective with sorghum, has
been initiated by the USDA/ARS in Georgia,
Glen Burton, and Wayne Hanna, USDA/ARS,
Tifton, Georgia (Personal communication). Longterm
pollen storage, rather than short winter
days, is used to achieve crossing of photosensitive
lines.
Disease Resistance
The second major component is disease resistance
itself, determined by screening to identify
sources of resistance, and documentation of
findings. Screening has identified sources of
high levels of resistance for most sorghum diseases.
Many are listed in Sorghum Diseases, a
World Review (Williams et al. 1980), and in papers
by Frederiksen and Rosenow (1980) and are
screened during or immediately following conversion
for disease resistance and other traits.
Rosenow and Clark (1987) list newly released
converted lines resistant to head smut, downy
mildew, and anthracnose.
Although good use has been made of identified
sources of resistance, improvement is
needed. New sources of resistance are always
needed as well as information regarding the differences,
if any, in genetic makeup. Uniformity
and reliability of rating schemes is an urgent
need. A standardized procedure for prompt
documentation of the improved material, and