RA 00048.pdf - OAR@ICRISAT

pines. South Africa, or Australia. This p r o b l e m of a
change in races of insects or diseases will
apparently continue to be w i t h us and plant
breeders will n e e d to c o n t i n u e to be alert and
ready to take care of t h e p r o b l e m s as t h e y arise.
A n d the breeding p r o g r a m w i l l a l w a y s b e c o m p l i ­
cated by t h e fact that any disease- or insectresistant
parents that e m e r g e m u s t produce
hybrids that have acceptable levels of hybrid vigor.
There are people i n t h e w o r l d w h o look u p o n
m o d e r n technology as a m e n a c e to society and
w h o think that plant breeders like us are courting
disaster for t h e h u m a n race. " G e n e t i c Vulnerability
of Major C r o p s " (Horsfall 1972) is t h e title of a
book that points o u t t h e danger inherent in plant
breeding procedures that result in a single hybrid
or variety being g r o w n extensively on large
acreages.
This danger is real but i s o v e r e m p h a s i z e d , in my
opinion. If o n e thinks that plant g r o w t h is controlled
b y innumerable g e n e s , o n e w o u l d think that
s o m e diversity, that m i g h t be n e e d e d later, is lost
if only o n e variety is lost. If, on t h e other hand, o n e
thinks that a relatively f e w g e n e s control g r o w t h
a n d t h e rest of t h e d o m i n a n t alleles result only in
normal plants, o n e w o u l d not be particularly
c o n c e r n e d about t h e loss of s o m e varieties as is
inevitable as plant breeding p r o d u c e s i m p r o v e d
strains a n d hybrids.
The n u m e r o u s g e n e s that are not involved w i t h
t h e regulation of plant g r o w t h , s u c h as t h o s e that
produce normal chlorophyll, m u s t be present in
t h e d o m i n a n t condition, o t h e r w i s e t h e plant will
be abnormal. Such d o m i n a n t g e n e s are not lost in
t h e plant breeding process to i m p r o v e t h e species
or to use hybrid vigor. All g e n e s appear to be
useful to t h e species, but in breeding for adaptation
or yield, plant breeders should be chiefly
interested in g e n e s that control t h e a m o u n t or rate
of g r o w t h or t i m e of differentiation.
The desirable g e n e s that exist in s o r g h u m
today, and are in hand, s h o u l d be incorporated into
cultivars or into parents of hybrids that are
adapted to t h e m a n y diverse e n v i r o n m e n t s in
w h i c h s o r g h u m i s n o w being g r o w n o r m a y b e
g r o w n in t h e f u t u r e . For instance, s o r g h u m
cultivars f r o m high elevations in Ethiopia m i g h t
w e l l contribute alleles that m i g h t result in hybrids
adapted to high elevations in t h e subtropics or at
high latitudes w h e r e prevailing t e m p e r a t u r e s in
t h e s u m m e r are l o w .
Unfortunately, m a r k e t i n g practices in t h e United
States w i l l be a p r o b l e m to f a r m e r s w h o m i g h t
w i s h to p r o d u c e a w h i t e - s e e d e d , n o n - w e a t h e r i n g ,
highly nutritional s o r g h u m hybrid. Grain of such a
hybrid w o u l d , at present, result in a discount at
t h e elevator if m i x e d w i t h t h e red grains of t h e
hybrids c o m m o n l y g r o w n . But s u c h difficulties
should not deter plant breeders f r o m w o r k i n g t o
i m p r o v e s o r g h u m nutrition because s o m e suitable
m a r k e t i n g procedure can undoubtedly be developed
w h e n n e e d e d .
I s e e m o r e plant breeding objectives today t h a n
w h e n I began t o w o r k o n s o r g h u m m o r e t h a n 5 0
years a g o ; not because t h e r e are m o r e p r o b l e m s ,
b u t because w e n o w recognize m o r e things that
should and can b e d o n e . I n t h e U n i t e d States, w e
do not have all of the p r o b l e m s that s o m e of y o u
have because w e d o not have s o m e o f your
insects, diseases, o r parasites. B u t w e have s o m e
p r o b l e m s that you do not have.
W e , as plant breeders, should stay as close to
e n t o m o l o g i s t s , plant pathologists, geneticists,
and plant physiologists as possible so that we can
profit f r o m their k n o w l e d g e and advice. I h o p e
that you realize h o w important your w o r k w i t h
s o r g h u m is and that you get as m u c h pleasure in
your activities as I do in m i n e .
References
D O G G E T T , H . 1970. S o r g h u m . L o n d o n a n d H a r l o w , U K :
L o n g m a n , G r e e n a n d Co., L t d .
EAST, E D W A R D M., and J O N E S , D O N A L D F. 1919. I n b r e e d ­
ing a n d o u t b r e e d i n g . Philadelphia a n d L o n d o n : J . B .
L i p p i n c o t t C o m p a n y .
FREDERIKSEN, R. A., and R O S E N O W , D. T. 1 9 7 9 . B r e e d i n g
f o r d i s e a s e r e s i s t a n c e in s o r g h u m . In P r o c e e d i n g s of
t h e International S h o r t C o u r s e in H o s t Plant Resista
n c e . M P - 1 4 5 1 . Texas A & M University, C o l l e g e Stat
i o n , Texas, USA.
HORSFALL, J A M E S G . 1972. G e n e t i c vulnerability o f m a j o r
c r o p s . National A c a d e m y o f S c i e n c e s , W a s h i n g t o n , D .
C , USA.
J O H N S O N , J. W . , R O S E N O W , D. T., M I L L E R , F. R., and
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ing f o r a r t h r o p o d r e s i s t a n c e in s o r g h u m . In P r o c e e d -
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