GENETIC ANALYSIS OF MORPHOLOGICAL AND PHYSIOLOGICAL TRAITS RELATED TO DROUGHT TOLERANCE IN GROUNDNUT (ARACHIS HYPOGAEA L.)
GENETIC ANALYSIS OF MORPHOLOGICAL AND PHYSIOLOGICAL TRAITS RELATED TO DROUGHT TOLERANCE IN GROUNDNUT (ARACHIS HYPOGAEA L.)
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Date
2020-07
Authors
ABDURRASHEED, Nafisa
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Abstract
Drought stress is one of the major constraints in groundnut producing areas of Sub-Sahara Africa
as its yield is reduced by 56-85%. Mitigating this constraint requires the selection of resilient
genotypes that withstand drought threats to groundnut production. The objectives of this study
were to identify drought tolerant genotypes to be used for groundnut breeding program, to assess
the mode of gene action controlling drought tolerance in groundnut and to determine the
association of pod yield with morphological and physiological traits related to drought tolerance
in groundnut. One hundred and seven (107) groundnut genotypes were screened for drought
tolerance during 2018 dry season in a split-plot design arranged in a randomized complete block
design under non-stress and water-stress conditions. The mean squares for the morphological and
physiological traits showed a highly significant (P≤0.01) difference between the genotypes under
water-stress and combined analysis. Based on the PCA ranking under water-stress condition,
genotypes ICGV-IS-13115, RS006F4B1-45®, ICGV-IS-07853, ICGV-IS-13989 and
RS006F4B-534 were the top 5 drought tolerant while genotypes ICGV-IS-07828, 12CS-010,
ICGV-IS-07809, RS006F4B1-45(B) and ICGV-IS-07904 were the least 5 drought susceptible.
Seven groundnut genotypes comprising of four drought susceptible and three drought tolerant
were randomly selected from the results of screening experiment. The seven genotypes were
crossed in a half diallel mating design to obtain 21 F1 progenies. The parents, 21 F1 progenies
and two checks were evaluated in a randomized complete block design with two replications
under both conditions. Data were collected on days to 50% flowering, plant height, pod yield,
100-seed weight SCMR at 40, 60 and 80 days after sowing (DAS) and harvest index (HI). The
analysis of variance showed a highly significant (P≤0.01) difference among the genotypes for
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plant height, number of pods per plant, pod yield and SCMR at 60 DAS under both conditions
while a significant (P≤0.05) difference for seed weight under water-stress condition, 100-seed
weight and HI under non-stress and water-stress condition was observed. Broad-sense
heritability was high (67.45%) for plant height, moderate (46.23%) for 100 seed weight and
(42.54%) for SCMR at 60 DAS under water-stress condition. General Combining Ability (GCA)
effect for all the traits were significant (P≤0.05) in both non-stress and water-stress conditions,
while Specific Combining Ability (SCA) effects were significant (P≤0.05) for all the traits in
both non-stress and water-stress conditions. Highly significant GCA effects for all the traits were
observed for ICG 5195 (P6) under water-stress condition, while ICGV-IS-07841 (P3) was a poor
general combiner under the same condition. Highly significant positive SCA effects for number
of pods per plant, seed weight and pod yield were observed with P1 x P6 and P3 x P6 crosses
under water-stress condition. SCMR at 60 DAS had a moderate positive and significant ( r =0.45,
P≤0.01) relationship with pod yield; HI recorded a strong positive and highly significant
( r =0.59, P≤0.01 and r =0.83 P≤0.01) relationship with number of pods per plant and pod yield.
Although both additive and non-additive gene actions were involved in the expression of most
traits, non-additive was more important than additive gene action under water-stress condition.
The importance of non-additive effect under water-stress suggests the need to achieve acceptable
progeny performance under drought stress condition. Therefore, cross P1 x P6 and P3 x P6 exhibit
highest SCA effects for number of pods per plant, seed weight and pod yield which can be
improved through pedigree selection. SCMR at 60 DAS and HI could also be used as an indirect
selection for pod yield under drought stress condition.
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 ANALYSIS,, MORPHOLOGICAL,, PHYSIOLOGICAL TRAITS RELATED,, DROUGHT TOLERANCE,, GROUNDNUT,, (ARACHIS HYPOGAEA L.)