Abstract
Wheat (Triticum
aestivum L.) germplasm of one hundred accessions were evaluated for
days to emergence, days to heading, days to maturity, number of
tillers plant-1, Plant height (cm), spike length (cm), number of
spikelets spike-1, grain yield plant-1(gm), 1000-grain weight (gm)
and Yield (Kg ha-1). Mean, range, standard deviation and coefficient
of variation were computed for each quantitative trait to estimate
the extent of genetic diversity present in the local wheat germplasm.
Corelation coefficient, cluster and Principal component analysis
were carried out. The whole set of germplasm was subjected to SDS-PAGE
analysis to investigate genetic variation for high HMW glutenin
subunits. To study the genetic variability of one hundred wheat (Triticum
aestivum L.) entries, an experiment was conducted during the growing
season 2004-2005 in augmented field design at research area of the
Department of Plant Breeding and Genetics, Faculty of Agriculture,
Gomal University, Dera Ismail Khan, NWFP, Pakistan. All the
germplasm was evaluated and characterized for the traits days to
emergence, days to heading, days to maturity, number of tillers
plant 1, Plant height (cm), spike length (cm), number of spikelets
spike-1, grain yield plant-1, 1000-grain weight and grain yield (kg
ha-1). Genetic diversity was found satisfactory for all the traits.
Variation was statistically found for all the parameters. Days to
emergence varied from 7.10 to 20.10 days having 24.03% coefficient
of variation. Days to heading ranged from 79.15 [PARC/NIAR 00203
(05)] to 130.25 [PARC/MAFF 004271 (01)] days with coefficient of
variation 9.35 %. Minimum days to maturity (136) were taken by the
entry PARC/NIAR 00203 (05) while the maximum days to maturity (193)
were taken by PARC/MAFF 004271 (01). The entry PARC/NIAR 002809 (01)
produced maximum number of tillers plant-1. PARC/NIAR 00203 (05) has
a maximum plant height (125.6 cm), while the entry PARC/MAFF 004270
(03) had the shortest plant height of (53.2 cm). Days to emergence
have positively significant correlation with number of tillers
plant-1 while, negatively significant correlation with days to
maturity. Days to heading have a significant and positive
correlation with days to maturity. Days to maturity have negative
correlation with xx plant height and number of tillers plant-1.
Plant height has a significant correlation with number of tillers
plant-1. The frequency distribution shows that spike length ranged
from 6.2 to 22.1 (cm). Variability was observed among the accessions
for spike length (cm), which varied from 6.50 to 21.90 (cm) with
mean value of 12.23 ± 2.28 (cm) and coefficient of variation for
this parameter was 18.63 %. The results of formal analysis revealed
that distant variability in spikelets spike-1 was detected which
ranged from 8.50 to 29.80 numbers of spikelets spike-1 with the mean
value of 16.35 ± 3.00 and coefficient of variation is 8.32%. The
frequency distribution for number of spikelets spike-1 showed the
variability from 7.1 to 31.00. The variation for grain yield plant-1
ranged from 1.26 to 4.58 (g) with mean value of 2.36 ± 0.52 and
coefficient of variation 21.89 %. Frequency distribution for grain
yield plan-1 ranged from 1.26 to 3.32 (g). 1000- grain weight (g)
varied from 15.74 to 46.65 (g) with the mean value of 34.20 ± 8.05
and coefficient of variation for this parameter was 23.55%. The
frequency distribution for 1000-grain weight (g) ranged from 15.20
to 47.19 (g). The variation for grain yield (kg ha-1) ranged from
2610 to 5058 (kg ha-1) with mean value of 4165 ± 504.45 (kg ha- 1)
and coefficient of variation for this character was 12.11%.
Frequency distribution for grain yield (kg ha-1) ranged from 2610 to
5065.9 (kg ha-1). Spike length revealed significant and highly
positively correlation with number of spikelets spike-1 (r = 0.20),
grain yields plant-1 (r = 0.16) and grain yield (kg ha-1) (r =
0.18), while this trait has negative correlation with 1000-grain
weight (r = -0.02). Highly significant and positive correlation was
reviewed in number of spikelets spike-1 with grain yield plant- 1 (r
= 0.49) and grain yield (kg ha-1) (r = 0.34). While positive
correlation of this trait was noted with 1000-grain weight (r =
0.02). Grain yield plant-1 had highly significant positive
correlation with 1000-grain weight (r = 0.30) and grain yield (kg
ha-1) (r =
0.62). Highly significant positive correlation was observed of 1000-grain
weight with grain yield (kg ha-1) (r = 0.44). The clustering of
accessions on the basis of morphological similarities grouped the
accessions into fifteen and thirteen clusters for the year 2005 and
2006 respectively. Whereas a scatter diagram on the basis of
altitude and latitude shows that accessions collected from 1200 ~
2000masl and 30o 39 to 34o 40N latitude have more morphological
similarities than with the other group. xxi The principal component
having greater than 1 eigenvalue contributed more than 61.62%
genetic variation among wheat accessions. The contribution of
genetic diversity by first three PCs was above 51.65% as compared to
PCs of the total accessions during both the years. The PC1 accounted
for 25.62% variation and was positively associated with majority of
the traits. The character, which contributed more positively to PC1,
was days to maturity. A considerable variation in total 12 different
HMW glutenin subunit
compositions was found. The frequency of 7+8 and 2+12 was the
highest in the entire set of germplasm. During the present
investigation fifteen accessions (PARC/MAFF 4272 (01), PARC/MAFF
4269 (01) PARC/MAFF 4358 (01), PARC/MAFF 4355 (02), PARC/JICA 3835
(05), PARC/MAFF 4358 (03), PARC/MAFF 4292 (01), PARC/MAFF 4354 (02)
PARC/MAFF 4354 (01), PARC/MAFF 4264 (03), PARC/MAFF 4280 (03) PARC/MAFF
4269 (02), PARC/MAFF 4279 (01), PARC/MAFF 4277 (01), PARC/MAFF 4277
(02)) possessing 5+10 allele, which is a known source for good bread
making quality, have been identified. According to experiment the
research material containing four wheat (Triticum aestivum L.)
varieties i.e. Bhakker-2002, Takbeer, BWP-2000 and Uqab-2000 with
twelve hybrids each of F1 and F2 generations were analyzed in a
randamize complete block design to observe the genetic analysis,
genetic advance, combining ability, heritability and heterotic
effects for different quantitative and qualitative parameters. The
cultivars were crossed in a complete diallel fashion according to
Hayman’s diallel analysis and Griffing’s approach for identification
of useful recombination’s in segregating generations which could be
used in any hybridization program. The adequacy of
additive-dominance was proved by Hayman Jinks modle, which proved
that the modle was adequate for all the parameters in F1 and F2
generations.The parents along with hybrids indicates significant
differences for maximum parameters presenting the genetic
segregation. In F1 generation, the additive and dominant variances
were found significant for all the parameters, except 1000-grain
weight. While the parameters i.e. days to to heading, spikelets
spike-1 and 1000-grain weight indicates non significant values for
dominant components. In F2 generation among all the parameters only
four parameters xxii i.e. days to heading, days to maturity, plant
height and 1000-grain weight were found to be non significant for
additive variance. The dominant variance was non significant for all
the parameters, except spike length in F2 generation. Hence it was
proved that majority of the parameters both in F1 and F2 generations
were governed by additive type of gene action. While degree of
dominance also proved by the results of F2 generation values which
were found lower than F1 generation values. Broad sense and narrow
sense heritability along with genetic advance was also noted both in
F1 and F2 generations for qualitative and quantitative parameters
indicating the importance of genetic variance. On the basis of
experimental research work it is cleared that the hybrids showing
significance for all the parameters indicating the genetic
divergence of the parents used in the wheat breeding program.
Acocording to general combining ability, specific combining ability
and reciprocal effects in F1 and F2 generations revealed significant
for all the parameters, except number of spikelets spike-1 which was
non significant for general combining ability and of number of
tillers plant-1, spike length, spikelets spike-1, number of grains
spike-1 and grain yield plant-1 were non significant for specific
combing abilty in F1 generation. The combining ability analysis
indicates that maximum parameters were governed by partial dominance
with additive gene action in F1 and F2 generations. However, maximum
hybrids proved as best general combiner. Therefore it was cleared
that comparatively low and high valus of the parents performed best
in specific combinig ability determination. Acoording to hetrotic
analysis it was cleared that heterosis over mid parenta was much
pronounced than heterosis over batter parents in F1 generation and
along with inbreeding depression in F2 generation. On the basis of
research findings due to additive gene effect, dominance gene
effect, specific gene effect, maternal effect, genetic advance,
broad sense heritability, narrow sense heritability, general
combining ability, specific combining ability and hetrotic analysis
with inbreeding depression, it was cleared that among all the
hybrids only the hybrids Takbeer x Uqab-2000, Bhakker-2002 x
BWP-2000 and Bhakker- 2002 x Uqab-2000 were found best potential
with all the desirable parameters for further wheat breeding program
under different agro climaticconditions in the area of Dera Ismail
Khan, NWFP, Pakistan for general cultivation.
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