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Wheat Information
Service
Number 82:11-18
(1996)
Genetic
analysis of some drought and yield related characters in Pakistani
spring wheat varieties
M. Aslam
Chowdhry, M. Tariq Mahmood, Naeem Mahmood and Ihsan Khaliq
Department of Plant Breeding and Genetics, University of
Agriculture, Faisalabad, Pakistan.
Summary
A Line x Tester analysis involving three wheat varieties viz.,
Pak. 81, LU26S,
K-1595 (males) and
six lines, having high and low abscisic acids viz., HABA 7, HABA 9,
HABA 20, LABA 7, LABA 9 and LABA 20
(females) were used for the study of some morpho-physiological
characters. LABA 20
showed the highest
negative GCA effects for specific flag leaf area and epidermal cell
size. Positive GCA estimates for tillers per plant, grains per spike
and grain yield per plant were obtained in LABA 9 and Pak. 81. Hybrid
HABA 20 x LU26S
showed highest
negative SCA effects for specific flag leaf area and epidermal cell
size. While HABA 9 x LU26S hybrid showed highest negative SCA effects
for stomatal size. SCA effects for tillers per plant, grains per
spike and grain yield per plant were positive in 50% of the hybrids.
Results of the study in total suggested the usefulness of Pak. 81 and
HABA 7 for further selection in the subsequent generations to
synthesize drought tolerant genotypes with appreciable yield
potentiaL This is because maximum mean values for the yield related
traits and minimum for epidermal cell size were observed in Pak. 81.
Furthermore all the crosses indicating maximum values for yield
characters and minimum for specific flag leaf area and stomatal size,
involved Pak. 81 as a tester. Pak. 81 was also best general combiner
for yield traits and specific flag leaf area. HABA 7 showed desirable
negative GCA effects for stress related traits and positive for yield
traits. Cross HABA 7 x Pak. 81 showed the suitable SCA effects for
all the characters except for epidermal cell size.
Introduction
Drought resistance, one of the utmost important objectives in
wheat breeding, is difficult to evaluate. The best criterion is the
yield of grain when the varieties are grown in critical drought
situations. Ability to retain green c colour of leaves and a well
turgid condition relates to drought resistance. Turgidity of the
leaves is conditioned by the proper regulation of opening and closing
of stomata and their size. A high endogenous level of ABA (Abscisic
acid) can cause the closure of stomata and in this way reduce the
rate of transpiration thus preventing moisture loss and moisture
stress to plant. Shimshi and Ephrat (1975) reported that wheat
cultivars with wider stomatal apertures were more productive without
greater water use. A substantial role of ABA in the control of plant
water relations was suggested by the discovery that some mutants,
which lack the ability to synthesize ABA, wilt easily because they do
not close their stomata to reduce water loss (Tal and Imber 1970).
External application of ABA to wilted plants restores their turgor.
ABA also enhances the growth rate thus enabling the plant to complete
its life cycle before a serious moisture deficit develops (Drought
escape). Thus parental lines with varying amounts of ABA were
included in this study.
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