Sorghum Diseases in India

Using Germplasm from the World Collection in Breeding
for Disease Resistance
D.T. Rosenow 1
Abstract
Breeding for disease resistance with emphasis on use of germplasm in the World Collection is
discussed. It deals primarily xvith sorghum, but includes references to pearl millet. Suggestions
regarding the collection, maintenance, storage, and distribution of seed of the Collection, as well as
database accumulation, storage, and dissemination are presented. The Sorghum Conversion Program
is discussed along with usefulness as a germplasm enhancement technique. For effective use,
germplasm sources possessing high levels of stable, heritable resistance must be identified and
appropriate screening techniques must be available. Breeding procedures are discussed and inheritance
patterns of major diseases given. The use of diverse germplasm, using large field screening
nurseries, simultaneous selection for disease resistance, good agronomic traits, other desirable
plant and grain traits, and the use of quick, visual rating are encouraged. The need for close
cooperation between breeder and pathologist is emphasized.
Introduction
Host-plant resistance is undoubtedly the most
important single element in the control of diseases
of sorghum and millet. Optimal benefit requires
cooperative research by pathologists and
breeders. It often seems a panacea to say the
solution to the problem is resistant varieties.
However, achieving the goal of developing a
disease-resistant variety that possesses the other
traits needed to make it a useful and acceptable
variety is not easy
Four requirements essential to a successful
disease resistance breeding program are: (1)
ability to screen and identify sources of resistance;
(2) sources of resistance must have sufficiently
high levels of resistance; (3) the resistance
must be heritable so that it can be transferred;
and (4) the resistance must be sufficiently
stable across environments and with time.
The genetic base of the sorghum species is
broad and diverse. Approximately 30 000 acces­
sions reside in the World Collection. The pearl
millet collection has approximately 19 000 accessions.
Effective use of the World Germplasm
Collection in breeeding for disease resistance requires
consideration of three major components:
(1) the Germplasm Collection itself; (2) disease
resistance techniques including screening, identification
of sources of resistance and determining
stability of resistance, and documentation;
and (3) the actual breeding and incorporation of
disease resistance into useful cultivars or hybrids.
Germplasm Collection
These elements include collection, maintenance,
storage, description, and classification of the
material, as well as database storage, retrieval,
and distribution. Although ICRISAT has done
admirable work with the collection, acquisition
of useful information on the lines, and charac-
1. Professor, Texas A&M Univereity Agricultural Research and Extension Center, Lubbock, Tx 74901, USA.
Rosenow, D.T. 1992. Using germplasm from the world collection in breeding for disease resistance. Pages 319-324 in Sorghum
and millets diseases: a second world review, (de Milliano, W.A.J., Frederiksen, R.A., and Bengston, G.D., eds), Patancheru,
A.P. 502 324, India: International Crops Research Institute for the Semi-Arid Tropics.
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