THE EFFECTS OF RADIATION ON POPCORN (Zea mays v a r . praecox S t u r t)
THE EFFECTS OF RADIATION ON POPCORN (Zea mays v a r . praecox S t u r t)
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Date
1993-08
Authors
ADAMU, ABU KASIMU
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Abstract
Air dried seeds of inbred line of popcorn (Zea
Mays Var. Praecox Sturt) were irradiated with gamma
rays (cobalt 60) at the doses of 10,20,30,40 and 400
Gray (gy) and thermal neutrons at 25,40,50,65 minutes
4 -2 -1
and 12 hours with a flux of 1.5 x 10 n.cm . S and
sown in the field, laboratory and green house.
Result of these treatments, demonstrated a drastic
reduction of seed germination, seedling height, root
length, and seedling survival. The reduction was
positively associated with the dose in both M and
1
M generation. However, there was a slight increase of
2
seed germination in M , raised from treatment at higher
2
doses (t400Gy and N12hrs) of M generation.
1
Among the induced dorminant seedlings mutants, are
the occurence of sectors of chloroplyll abnormalities
(albina, xantha virescent; lustescent; chlorina and
striata) and other morphological changes in appearance;
most of which are lethal or unfavourable to growth in
both M and M generation. The mean number of mutants per
1 2
mutation were found to be 7.05 in gamma rays and 6.15 in
thermal neutrons.
The capacity of favourable mutants induced include
increase in tiller formation, number of cobs per
plants; increased earliness; earlength; and seed weight
in most of the treatments. The increase were in direct
proportionality with the dose and were more frequent in
gamma rays than in thermal neutrons.
The class of dominant mutants observed at
maturity, include traits such as tassel seed, male
sterility and morphological traits not expressed in the
seedling stage. However, most of the classes were not
transmitted to M generation and the highest percentage
2
observable was not more than 4% in both gamma rays and
thermal neutrons and were mostly confined to higher
doses.
There was also no correlation between the group
of mutation (Chlorophyll deficient) observed and male
sterility; and not only the frequency is independent of
the degree of male sterility, but also the spectrum of
chlorophyll mutation does not indicate any connection
with M and M male sterility.
1 2
The frequency of mitotic and meiotic aberrations
induced include, formation of multivalents(translocation),
non pairing, laggards; fragments; eliminated; nonoriented
chromosomes, single and dicentric bridges
(inversions), induced deformed and aborted pollen
grains at different doses in both M and M generation.
1 2
Thus considering the total results on the capacity
of favourable mutants; genetics and cytogenetics of
gamma rays and thermal neutrons induced mutations seems
to be of practical values. In particular the increase
in the number of tillers, cobs, earliness,
male sterility, ear length, seed weight are beneficial
chracters which could be exploited and utilized for
breeding of popcorn.
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL, AHMADU
BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE (M.Sc)
IN BOTANY
AUGUST, 1993
Keywords
EFFECTS,, RADIATION,, POPCORN, (Zea mays,, v a r ,, praecox S t u r t)