GENETIC VARIATIONS AND ROSETTE RESISTANCE IN EARLY GENERATIONS OF GROUNDNUT (Arachis hypogaea L.) VARIETIES IRRADIATED WITH GAMMA RAYS
GENETIC VARIATIONS AND ROSETTE RESISTANCE IN EARLY GENERATIONS OF GROUNDNUT (Arachis hypogaea L.) VARIETIES IRRADIATED WITH GAMMA RAYS
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Date
1999-08
Authors
OGUNLADE, OLUKEMI
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Abstract
Seeds of groundnut, Arachis hypogaea L. were treated with
gamma rays. Two sets of irradiations were performed. The first set
consisted of irradiating five varieties (two early maturing, SAMNUT
14 and 18, one medium maturing, UGA-7, and two late maturing,
SAMNUT 21 and 10) at 10, 35, 45, and 50 krads with cobalt 60(C60 )
source. An F2 population, Ex RM12 (derived from an Ex-Dakar X RMP
12 Cross) was used as control in the set. Only lOkr treated plants
survived for all the varieties, these were evaluated for increased
variability, agronomic performance and for resistance to groundnut
rosette disease at M2 and M3 populations. The second set of
Irradiation was done at lower doses 15, 20, 25, 30 and 35kr with 0
dose serving as control using the 5 varieties. Varieties survivity
under all these lower doses and were evaluated in M1 and M2
populations as the first set. These varieties were grown under two
field conditions: rosette and rosette free.
Results indicate wide ranges and coefficients of variability
for the characters studied. Population means showed significant
differences in performance of irradiated populations and control
within each variety for the characters measured. Effects of doses
produced more detrimental changes in the M2 than in the M2.
Increases in yield and components were seen within varieties for
the lower doses 15kr, 20kr and 25kr than at higher doses 30 and
35kr especially at M2. Significant (P= 0.05) effects were record
for the doses used and for the varieties planted. Interaction of
varieties and doses were not significant. Estimates of genetic
variance were large in the populations, interaction variance were
negative or small. Abnormally high broad sense heritability
estimates were obtained for the M2. Positive and highly
significant (P=0.01) correlations between yields and its components
were recorded in M2 except between one hundred seed weight and
shelling percentage.
Effects of the mutagenic agents on the varieties were similar
on rosette infested and rosette free fields. The irradiated
populations of each variety showed variations in their reactions to
disease infections.
The performance of irradiated populations compared with
control indicated that doses 15, 20 and 25kr generally produced
more beneficial, significant changes in plants while dose lOkr was
not too far from the control and dose 30 and 35kr produced more
detrimental effects on characters studied. Selections from M3 and
higher generations of populations irradiated with 15, 20, and 25kr
may produce higher yielding and disease (rosette) resistant
mutants.
Description
A thesis submitted to the post graduate school, Faculty of Agriculture, Ahmadu Bello University, Zaria, in
partial fulfillment for the degree of Master of Science in the Department of Plant Science.
August, 1999
Keywords
GENETIC,, VARIATIONS,, ROSETTE,, RESISTANCE,, EARLY,, GENERATIONS,, GROUNDNUT,, (Arachis hypogaea L.),, VARIETIES,, IRRADIATED,, GAMMA,, RAYS.