GENETIC VARIABILITY FOR YIELD AND OTHER AGRONOMIC TRAITS OF GROUNDNUT(ARACHIS HYPOGAEA L.) AS INDUCED BY SODIUM AZIDE
GENETIC VARIABILITY FOR YIELD AND OTHER AGRONOMIC TRAITS OF GROUNDNUT(ARACHIS HYPOGAEA L.) AS INDUCED BY SODIUM AZIDE
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Date
2020-02
Authors
OGBAN, Itunonun Ina
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Abstract
Groundnut improvement, through conventional method of breeding may not be able to create
desired variability on which a robust breeding programme could be built. Also, groundnut as
a self- pollinating crop naturally would have less variability in its gene pool. Thus, the
present study was conducted (i) To determine the sensitivity of two groundnut genotypes to
different treatment doses of Sodium azide (ii) To determine the effective treatment dose of
Sodium azide for induction of variability among the genotypes, and, (iii) To evaluate
variability for some agronomic traits modified by Sodium azide treatment. Two groundnut
genotypes SAMNUT 22 and SAMNUT 24, obtained from IAR were treated with 10 mM, 20
mM,30 mM,40 mM, and 50 mM of Sodium azide concentration at the groundnut
improvement lab for 6 and 12 hours. Each of the treated seeds and the controls were sown
directly to well-prepared seed bed in the field to obtain the M1 plants. During the off season,
a set of 10 seed each were picked from each treatment for seed multiplication. A total of 24
M1 families were evaluated in a Randomized Complete Block Design(RCBD) with two
replications in 2018, while a total of 72 M2 families were also evaluated in a 9 x 12
augmented design with 4 checks. Data were collected and significant differences (P<0.05)
were observed for the effect of Sodium azide treatment on emergence count, and number of
pods per plot (NPP) for all genotypes. Highly significant differences (P < 0.01) were
observed for number of days to 50% flowering, number of branches, plant height and 100
seed weight for all the genotypes. Highly significant (P < 0.01) difference for genotype by
dose interaction was observed for number of pods per plots (NPP). SAMNUT 24(t = 1.2) was
more sensitive to Sodium azide treatment than SAMNUT 22(t=0.5). The mutagenic
frequency recorded in the present investigation ranged from 29 % to 5 %. The mutagenic
frequency varied across the different concentration, also a decreasing trend with increase in
concentration of the mutagen was observed. The mutation frequency was found to be low
possibly because of low physiological damage and the low response of groundnut at the
maturity stage. The higher effectiveness and efficiency of Sodium azide treatment observed
at 10 mM for 12hours of SAMNUT 24 indicates that lower doses were more effective in
inducing variability in agronomic traits of groundnut. A decrease in mutagenic effectiveness
with increase in concentration dose of the mutagen was also observed across the genotypes
this is as a result of the failure in proportional increase of mutation frequency with the
increase in concentrations/doses of the mutagen. The differences in the mutagenic
effectiveness of the genotypes studied indicate that the genotypes responded differently to
Sodium azide treatment. The Mutagenic efficiency did not follow any particular trend
(increase or decrease), it varied across the mutagenic treatments. A high significant
difference was observed among treatments, controls and interaction of emergence count and
number of seeds per pod (NSP) in the M2. Analysis of variance for the different traits
revealed highly significant difference among the 2 genotypes for all the agronomic traits
studied. The existence of these differences indicates the presence of sufficient genetic
variability among the genotypes for these traits. The phenotypic component of variation
estimates, were generally higher than the Genotypic component of variation estimates for all
the studied traits except for plant height which had higher genotypic component of variation,
thus indicating a level of environmental influence on the expression of the traits. The M2
mutant, 10 mM6 SAMNUT 24 at 6hours recorded the highest 100-seed weight (123.0 g)
among the other mutants while 50 mM2 SAMNUT 22 at 6hours recorded the highest shelling
percentage (93.0). Mutant 50 mM1 SAMNUT 24 at 12 hours had the highest number of pods
per plot (386.6), mutant 10 mM3 SAMNUT 24 at 6hours had the highest plant height (33.6),
mutant 40 mM2 SAMNUT 22 at 6hours had the least days to 50% flowering (28), Mutant 20
mM4 SAMNUT 24 at 12 hours had the highest pod yield per plot. The mutants had higher
and better value than their controls, thus the presence of variability induced by Sodium
azide on the agronomic traits. For the improvement of cultivated groundnut, it is pertinent to
use diverse collections with more variability and also employ the use of varying
concentration, for the purpose of variety development and for use in future breeding
program.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES
AHMADU BELLO UNIVERSITY
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF
MASTER OF SCIENCE DEGREE IN PLANT BREEDING
DEPARTMENT OF PLANT SCIENCE
FACULTY OF AGRICULTURE,
AHMADU BELLO UNIVERSITY,
ZARIA, NIGERIA
Keywords
GENETIC VARIABILITY,, YIELD,, AGRONOMIC TRAITS,, GROUNDNUT,, (ARACHIS HYPOGAEA L.),, INDUCED,, SODIUM AZIDE.