A Database for Triticeae and Avena
Cytogenetics Laboratory, Department of Botany, Coimbatore-641
V.R.K. Reddy and K.M. Gothandam.
Six leaf rust-resistance genes (Lr9, Lr19, Lr24,
Lr28, Lr32, and Lr37); three stem rust-resistance
genes (Sr24, Sr25, and Sr38); and one stripe
rust-resistance gene (Yr17), present singly or in combination
(in linked condition), were transferred from alien hexaploid wheat
stocks into four Indian hexaploid wheat cultivars (HUW 318, PBW
226, HI 1077, and WH 542). Near-isogenic lines in each BC2F5 and
BC5F5 were made from all the 24 cross combinations. The immune
to moderately resistant reaction at the seedling stage and highly
resistant reaction at the adult-plant stage provided by these
genes strongly advocate the use of specific rust-resistance genes
(or gene complex) for durable resistance. The constituted lines
with specific genes for stem, leaf, and stripe rust (Sr24,
Lr32, and Yr17) had a variable rust reaction pattern,
so the resistance provided by these genes may be due to a combination
or interactive effect with genes already present in the recurrent
parent. Constituted lines with the rust-resistance genes Lr9,
Lr28, and Lr32 also have reduced severity to a different
rust, indicating that the donor parents with these resistance
genes also carry unknown resistance genes for other rusts.
In general, the agronomic performance of plants of the BC2F5
was superior to that of the BC5F5 for plant height, tiller number/plant,
spike length, number of spikelets/spike, 100-grain weight, and
grain yield. The NILs constituted at the BC2F5/BC5F5 had reasonably
very good agronomic characteristics, although seed quality characteristics
(shrivelling, weight, size, and color) were very poor. Therefore,
final selections were made based on seed quality coupled with
good agronomic characters. Among the NILs in the BC5F5 population,
lines with rust-resistance genes Lr19 + Sr25, Lr24
+ Sr24 and Lr32 produced seeds of good quality,
and lines with Lr28 and Sr38 + Lr37 + Yr17
produced seeds of inferior quality. A total of 17 lines finally
were selected for commercial purposes, and the remaining seven
lines were grouped as genetic stocks for use in further breeding
programs. The constituted NILs gave significantly higher grain
yield than the untreated control plants. Constituted NILs gave
7-38 % more grain yield than the untreated control. However, when
compared to the chemical treated control, both increases and decreases
in grain yield were noticed. The increase was in the range of
11 to 19.5 %, whereas the reduction was in the range of -0.68-7.45
%. The hexaploid wheat stock Cook*6/C80-1 (Lr19 + Sr25)
followed by Sonalika *7/Abe (Lr9) and Darf *6/3Ag/Kite
(Lr24 + Sr24) were determined to be the best donor
Thirty four specific rust-resistance genes Lr9, Lr19,
Lr24, Lr25, Lr26, Lr28, Lr29,
Lr35, Lr36, Lr37, Lr38, Lr39,
Lr40, Lr41, Lr42, Lr43, Lr44,
Lr45, Sr24, Sr25, Sr26, Sr27,
Sr28, Sr31, Sr38, Sr39, Yr9,
Yr11, Yr12, Yr13, Yr14, Yr15,
Yr16, and Yr17 were transferred to the four Indian
hexaploid wheats HS 240, HD 2402, HD 2009, and HP 1102. Gene transfers
were confirmed on the basis of morphological, genetical, biochemical,
and molecular markers. Morphological markers for awnless spikes
(Eagle-Sr26), lax spikes (RL 8061-Sr38+Lr37+Yr17),
reduced yellow pigment in the flour (Cook*6/C 80-1-Lr19+Sr25),
club spikes (W 3353-Sr27), waxiness (Veery 'S'-Sr31+Lr26+Yr9),
and white glumes (TR 380-14 7/3 Ag#14-Sr24+Lr24)
were used. Representative NILs were crossed with the universally
susceptible wheat variety Agra Local. All F1 hybrid plants were
rust resistant. The F2 segregation was 3 resistant:1susceptible;
BC1 hybrids were in a 1 resistant:1 susceptible ratio. F2 plants
derived from F1 monosomic and disomic hybrids between monosomic
Chinese Spring and the representative rust-resistant NILs for
Lr38 (HD 2009), Lr44 (HP 1102), Sr28 (HS
240) and Yr17 (HD 2402) segregated in a 3:1 ratio of resistant
to susceptible for respective rust genes except for lines 6D,
1B, 2B, and 2A, confirming the successful incorporation of the
rust-resistance genes into their respective chromosomes of the
Inoculated, rust-resistant NILs had a higher peroxidase activity
compared to the healthy controls. The polyphenol oxidase activity
showed an increase in both susceptible wheat parents and rust-resistant
NILs 24 hours after inoculation. The activity remained higher
in the resistant plants during later stages of infection. Increases
in catalase activity in both the susceptible wheat parent and
the rust-resistant NILs 1 day after inoculation were noticed.
The activity remained higher during later stages of infection
in both susceptible and resistant plants. However, the overall
activity was higher in susceptible wheat parents than in the resistant
NILs. Lipoxygenase activity increased in both the susceptible
wheat parents and their rust-resistant NILs 2 days after inoculation,
but subsequently declined 7 days after inoculation with the respective
rust pathogen in resistant plants. A consistent increase was noticed
in the susceptible parents. The total lipid content of the leaves
increased in both susceptible and rust-resistant NILs 2 days after
inoculation, but subsequently decreased with increased time postinoculation.
The percent decrease was greater in susceptible parents than the
resistant NILs. The total soluble protein content in susceptible
plants decreased as the time after inoculation increased, whereas
in resistant NILs, the protein increased up to 48 hours postinoculation
and subsequently showed a decrease in the later stages of infection.
However, the percent decrease was more in susceptible than resistant
plants 7 days after inoculation.
A significant decrease in the specific activities of RNase-I
and combined RNase-II Nuc-I were observed in resistant NILs compared
to the susceptible parents 10 and 15 days after inoculation with
the rust spores. Resistant NILs had a relatively higher chlorophyll
content than the susceptible wheat parents. Resistant NILs were
able to retain a relatively steady level of chlorophyll content,
whereas the chlorophyll content in the susceptible wheat parents
decreased at a faster rate until reaching a level of less than
50 % of that in resistant NILs. The total free amino acid content
increased until the 8th day after inoculation in both the susceptible
parent and in the resistant NILs, after which there was a slight
reduction occurred in both. The increase was more pronounced in
the resistant lines than in the susceptible parents. During the
second week after inoculation, resistant plants were able to maintain
a level of total free amino acids significant increases in total
free phenols and tannin content were observed in the constituted
NILs compared to their respective recurrent wheat parents. The
constituted NILs and had significantly higher nuclear DNA than
their respective susceptible wheat parents.
The NILs for leaf rust-resistance gene Lr9 together
with their parents were screened for polymorphism at the molecular
level using the previously identified RAPD primer OPA-01 (Schachermayr
et al. 1994), which has complete linkage to Lr9. The RAPD
primer OPA-07 amplifies a 1,500-bp fragment and resulted in an
additional band in the resistant NILs. Similarly, primer OPJ-13
distinguished resistant and susceptible lines and amplified a
fragment of 1,100 bp as weak band and in NILs with the Lr49
gene in the wheat NILs. A polymorphism between the NILs for gene
Lr24 was identified using the previously identified RAPD
primer OPJ-09. This primer amplifies a fragment at 550 bp in all
the NILs with Lr24.
Genes for hybrid necrosis and chlorosis have been identified
in approximately 100 hexaploid and tetraploid wheats.
MARATHWADA AGRICULTURAL UNIVERSITY
Wheat and Maize Research Unit, Parbhani 431 402 Maharashtra,
The Wheat and Maize Research Unit at MAU-Parbhani received
a sanction for a project entitled 'Use of Nuclear Techniques in
Genetic Enhancement of Wheat Quality' for 1999-2001. The main
subject is the improvement of quality traits of T. durum
by nuclear techniques. High quality HMW and LMW glutenins and
gliadins present in the D genome of the wheat PBNS-l666 are to
be transferred to the A or B genomes of T. durum. The improved
Parbhani durum PBND-527 will be used for breeding and the progeny
subsequently screened by molecular and cytogenetic techniques.
A Kisan Melawa on the cultivation of T. durum wheats
was organized on 19 February, 2000. Vice-chancellor Dr. C.D. Mayee,
president of the program, stressed the need to grow T. durum
for export purposes. Currently, the best durums are available
through the All-India Wheat Project Program. Dr. N.D. Raut, joint
director of Agriculture Aurangabad stated that the area under
rain-fed wheat should be increased because of suitable climatic
conditions. Dr. K.A. Nayeem gave details on the use of T. durum
for industrial purposes, and noted that small industries are needed
for the preparation of end products.
P.J. Kulkarni and K.A. Nayeem.
Evaluation of genetic variability in the available crop species
is the first step toward selecting better performing genotypes
among divergent groups in plant breeding programs. Wheat is one
of the most important cereal grains in the world. The analysis
of various morphological characters in addition to chlorophyll
content at flowering can help to identify desirable genotypes
Significant differences among the genotypes were observed for
all the 15 characteristics, suggesting the presence of sufficient
variability among the genotypes for these traits (Table 1).
PBND-850 was observed to be the earliest flowering (62.50 days),
PBND-4279 had the longest ear (9.99 cm), PBND-4277 had the shortest
peduncle (25.5 cm), and DWR-1006 had the highest number of spiklets/spike.
For photosynthetic capacity, PBND-4250 (1.53) was the top ranking
line, and PBND-785 had the highest spike density (3.12). The highest
total chlorophyll content was observed in PBND-4260 (3.13 mg/g).
We can utilize the above genotypes as potential donors in an appropriate
breeding program for improving durum wheat. Table 2 lists the
desirable genotypes for various selected characteristics.
In the present study, spikelet density had the highest coefficient
of variation (5.28 %) followed by photosynthetic capacity (4.75
%) and extruded peduncle length (4.46 %). The lowest coefficients
of variation were observed for total chlorophyll content (1.54
%) followed by days-to-50 % flowering (1.58 %).
Genotypic and phenotypic coefficients of variation were lowest
for days-to-50 % flowering, as also was observed in studies by
Takawale et al. (l989) and Getchew et al. (1993). The highest
genotypic and phenotypic coefficients of variation were observed
for extruded peduncle length. In general, estimates of the phenotypic
coefficient of variation were higher than the corresponding estimates
of genotypic coefficient of variation (Yadav and Mishra 1993).
Very high, broad sense estimates of heritability were observed
for all characteristics studied except spikelet density. High
heritability percents were observed for total chlorophyll content
(98.90 %), extruded peduncle length (97.90 %), and awn length
(97.30 %). High heritability along with sufficient genetic advance
estimates are useful as selection criteria. Among all the characteristics
studied, the estimated highest genetic advances were for extruded
peduncle length (10.93 %) and peduncle length (9.37 %).
Correlation studies. The genotypic, phenotypic, and environmental
correlation coefficients among the 15 characteristics were calculated.
A negative and significant correlation was observed for photosynthetic
capacity with flag leaf area at all levels. The number of spikelet/spike
had a significant positive correlation at the environment level
with photosynthetic capacity. Total chlorophyll content had a
significant positive correlation with chlorophyll a content, chlorophyll
b content, and carotenoid content at both the genotypic and phenotypic
Path coefficient analysis. A path coefficient analysis was
worked out taking the number of spikelets/spike as a dependent
variable and the remaining 14 characters as independent variables.
The greatest direct effects on the number of spikelets/spike was
for flag-leaf length (1.798), spikelet density (1.323), and spike
Among the estimates of indirect effects, no positive indirect
effect was observed for the number of spikelet/spike. For selection
criteria, emphasis should be placed on the characteristics of
flag-leaf length, spikelet density, and spike length.
CH. CHARAN SINGH UNIVERSITY
Department of Agricultural Botany, Meerut (U.P.), India.
P.K. Gupta, H.S. Balyan, M. Prasad, R.K. Varshney, and J.K.
The Department of Biotechnology and the Government of India,
under the Wheat Biotechnology Network Programme, had sanctioned
a project entitled 'Characterizing and using the Quality Traits
in Wheat Aided by Molecular Markers.' The other network partners
include Punjab Agricultural University (PAU), Ludhiana; G.B. Pant
University of Agriculture & Technology, Pantnagar; Directorate
of Wheat Research, Karnal; National Chemical Laboratory, Pune;
and Agharkar Research Institute, Pune. The major objective of
the project at our center is the development of molecular markers
for three grain quality traits including grain protein content
(GPC), grain size (GS), and preharvest-sprouting tolerance (PHST).
Development of molecular markers. Both hybridization-based
and PCR-based markers have been tried. These included (i) oligonucleotide
in-gel hybridization, (ii) RAPD, (iii) DNA-amplification fingerprinting
(DAF), (iv) STS, (v) microsatellite-primed PCR (MP-PCR), (vi)
sequence-tagged microsatellite sites (STMSs), (vii) AFLP, and
(viii) selective amplification of microsatellite polymorphic loci
(SAMPL). However, the most useful approaches for detection of
relatively high level of polymorphism included STS, STMS, AFLP,
and SAMPL. For enrichment of the number of STMS molecular markers,
we also entered into an international collaboration, which led
to the availability of 500 locus-specific STMS primer pairs. This
international effort is under the auspices of the Wheat Microsatellite
Consortium, of which we are the only member from India. Subsequently,
we identified five molecular markers including two each for GPC
and PHST and one marker for GW. Of these five markers, four are
STMS (STR or microsatellite) markers and one is an STS marker.
Using nullisomic-tetrasomic and ditelocentric stocks, the loci
for these markers also were assigned to specific chromosome arms
(Table 1). Recombinant-inbred lines for all these three traits
were developed by Drs. H. S. Dhaliwal and Harjit-Singh at PAU,
Marker validation of two identified STMS markers for GPC using
NILs. In order to validate the two STMS markers linked with GPC,
three sets of 10 NILs for high GPC were derived using two genotypes
with low GPC (WL711 and HD2329) as recipient parents and another
two genotypes with high GPC (PH132 and PH133) as donor parents
(these NILs were developed by Dr. Harjit-Singh at PAU, Ludhiana).
One NIL with high GPC (12 %) derived from HD2329 when analyzed
with WMC41 gave a characteristic amplification profile similar
to that of its donor parent PH132. Another NIL 2215 with high
GPC (12 %) derived from WL711 when tried with WMC415 also gave
an amplification profile resembling that of its donor parent PH133.
The remaining eight NILs with high GPC gave patterns similar to
those of their corresponding recipient parents with both the markers,
suggesting that QTLs other than those associated with the above
markers actually were transferred from the donor parents and contributed
to high GPC in these NILs. Thus, marker validation using NILs
with high GPC, although demonstrating the utility of these two
microsatellite markers for their use in marker-assisted selection
in plant breeding, also suggested that many more QTLs could be
present and need to be identified using molecular markers (Harjit-Singh
et al. 2000).
Preparation of integrated physical maps of 2DL, 6BS, and 7DL
with loci for grain-protein content and preharvest-sprouting tolerance
in bread wheat. With the use of nullisomic-tetrasomic and ditelocentric
lines, the marker Xwmc41 (linked with GPC) was located on 2DL,
and two other markers, Xwmc104 and Xmst101 (linked with PHST),
were localized on 6BS and 7DL, respectively. With the use of overlapping
deletion lines for the long arm of chromosome 2D, the marker locus
Xwmc41 was assigned to the terminal 0.24 fraction of 2DL. Also,
from the two molecular markers associated with PHST, WMC104 (an
STMS marker) was assigned to the terminal 0.76 fraction of the
6BS satellite and MST101 (an STS marker) was assigned to the proximal
centromeric 0.10 fraction of 7DL. Thirteen STMS markers, previously
mapped genetically on 6BS and 7DL, also were assigned to specific
physical regions of these two arms. The markers that were physically
mapped during our study were integrated with those previously
mapped in a similar manner, and integrated into physical maps
with 27 markers on 2DL, 16 on 6BS, and 54 on 7DL (Varshney et
Genetic mapping of Xwmc41 using ITMI mapping population.
The molecular marker WMC41 (linked with a QTL for GPC) was mapped
genetically using the ITMI population in collaboration with Dr.
M. Röder, IPK, Gatersleben Germany. The marker locus Xwmc41-2D
was found between the RFLP markers Xfb122 and Xfb068,
which matches with the physical map.
Genetic diversity studies using STMS, AFLPs, and SAMPLs. A
set of 55 elite wheat genotypes (originating in 29 countries and
representing six continents) was used to estimate genetic diversity
among wheat genotypes using three types of markers: STMS, AFLPs,
and SAMPLs. Twenty wheat STMS (microsatellite) markers were used
to examine their utility, first for detecting DNA polymorphism,
second for identifying genotypes, and third for estimating genetic
diversity among wheat genotypes. A total of 155 alleles was detected
at 21 loci using the above microsatellite primer pairs (only one
primer amplified two loci; all other primers amplified one locus
each). Of the 20 primers amplifying 21 loci, 17 primers and their
corresponding 18 loci were assigned to 13 different chromosomes
(six A-genome, five B-genome, and two D-genome chromosomes). The
number of alleles per locus ranged from 1 to 13, with an average
of 7.4 alleles per locus. The values of average polymorphic information
content (PIC) and the marker index (MI) for these markers were
estimated to be 0.71 and 0.70, respectively. A dendrogram, prepared
on the basis of a similarity matrix using the UPGMA algorithm,
delineated the above genotypes into two major clusters (I and
II), each with two subclusters (Ia, Ib and IIa, IIb). One of these
subclusters (Ib) consisted of a solitary genotype (E3111) from
Portugal, which was unique and differed from all other genotypes
belonging to cluster I and placed in subcluster Ia. With a set
of only 12 primer pairs, a maximum of 48 of the 55 wheat genotypes
could be distinguished. Further additions of primers to this set
did not prove useful for distinguishing the remaining genotypes.
The results demonstrated the utility of microsatellite markers
for detecting polymorphism leading to genotype identification
and for estimating genetic diversity (Prasad et al. 2000).
An AFLP analysis also was conducted using eight primer-pair
combinations with the 55 wheat genotypes. Each of these combinations
gave a large numbers of AFLP fragments from the 55 accessions.
A total of 287 polymorphic bands (46 %) out of 612 bands were
identified (mean = 76 bands per primer pair), confirming the high
multiplex ratio of AFLPs. The highest percentage of polymorphism
(74 %) was obtained with primer combination EACG x MCAG, whereas
the lowest value (22 %) was obtained with primer combination EAAC
x MCAT (Table 2). The genetic similarity coefficients for all
the possible 1,485 genotypes pairs ranged from 0.44 between genotypes
E2401 and E661 to 0.99 between genotypes E3901 and E4328 and averaged
to 0.71. The UPGMA cluster analysis was used to prepare a dendrogram,
and the genotypes were grouped into two major clusters.
The SAMPL technique, which combines the features of microsatellites
and AFLPs, also was used to study genetic diversity among the
55 wheat genotypes. We successfully used two SAMPL primer combinations.
Several polymorphic fragments were obtained with each combination.
The results of SAMPL are quite encouraging. Out of a total of
87 bands, 43 polymorphic bands (49 %) were identified. The average
number of scorable bands per primer-pair combination was 44. The
maximum number of bands was obtained with primer SAMPL-7. The
highest percentage of polymorphism (52 %) was obtained with primer
SAMPL-6 (Table 2). Genetic-similarity coefficients for pairs of
genotypes ranged from 0.35 between genotypes E288 and E3389 to
0.96 between genotypes E4229 and E4813 and between E3839 and E3901.
The average genetic similarity coefficient was 0.65. Clusters
were constructed using Jaccard's similarity coefficients, and
the genotypes were grouped further into two major clusters.
The SAMPL and AFLP were also compared. SAMPL gave 52 % polymorphism,
whereas AFLP gave 46 %. The maximum genetic similarity coefficients
were 0.99 in AFLP and 0.96 in SAMPL, whereas the minimum genetic
similarity coefficients were 0.44 in AFLP and 0.35 in SAMPL. Comparing
both SAMPL and AFLP markers, SAMPL was considered to be more informative
AFLP/SAMPL for gene tagging. Keeping in view the potential
of AFLP/SAMPL, we also have initiated work involving the use of
AFLP/SAMPL approach for gene tagging. At present, we are studying
polymorphisms among different parents, PH132 (high GPC) and WL711
(low GPC), Rye Selection 111 (high GW), Chinese Spring (low GW),
SPR8198 (tolerant to PHS), and HD2329 (susceptible to PHS). A
number of polymorphic bands already have been identified using
both AFLPs and SAMPL. Bulk segregant analysis and selective genotyping
will be made using these polymorphic marker(s) to study association
of the marker(s) with quality traits.
Retrotransposon-based techniques (REMAP and IRAP) for gene
tagging. Another novel, microsatellite-based approach makes use
of one retrotransposon primer with one SSR primer and is described
as REtrotransposon Microsatellite Amplified Polymorphism (REMAP).
We successfully used by REMAP to study DNA polymorphisms among
parents PH132 (high GPC) and WL711 (low GPC), rye selection III
(high GW) and Chinese Spring (low GW), and SPR8198 (tolerant to
PHS) and HD2329 (susceptible to PHS). Primers based on a single
retrotransposon also can be used to amplify the inter-retrotransposon
spacer region. This technique, described as Inter-Retrotransposon
Amplified Polymorphism (IRAP), also is being tried by us for gene
Genetic diversity and genomic relationship in tribe Triticeae
using in-gel hybridization and STMS markers. Four SSR probes in
combination with four restriction enzymes were used for in-gel
hybridization in a set of 25 wild accessions representing 15 species
to study genetic diversity and its relationship with genomic constitution.
Similarly, 15 STMS primer pairs also were used in a PCR study
of genetic diversity in 19 accessions representing 14 wild species
having different genomic constitutions. Based on the above studies,
dendrograms were prepared, and the results are being analyzed.
SKUAST REGIONAL AGRICULTURAL RESEARCH
Sher-E-Kashmir, University of Agricultural Sciences &
Technology, R.S. Pura-181 102, Jammu, India.
J.S. Bijral, S.K. Mondal, and Kuldip Singh.
Although the yield advantage of rice hybrids is being assessed
on a commercial scale, the anticipated yield increase from wheat
hybrids has not been realized. Several workers (Briggle 1963,
Johnson and Schmidt 1968, Zeven 1972) have reviewed the literature
on heterosis in wheat, and only in a few instance have wheat hybrids
been shown to be significantly superior to the best conventionally
bred wheat varieties.
In order to obtain realistic estimates of standard heterosis,
a set of 212 crosses was produced during 1997-98. Of the 212 F1
hybrids, 141 were 'winter/spring' wheat crosses. The remaining
71 were spring wheat combinations. The hand-produced hybrids,
along with the best inbred wheat variety PBW-343, were grown in
randomized complete block design with two replications during
the 1998-99 season. Each entry was planted in single, 3.5-m row
with spacings of 25 cm between the rows and 10 cm between plants.
Observations on grain yield/spike (in grams), number of fertile
tillers/plant, number of grains/spike, and 1,000-kernel weight
(in grams) were recorded on five random competitive plants from
each row. Heterosis (standard) was estimated over the check PBW-343.
Of the 212 hybrids, 68 exhibited more than 15 % standard heterosis
for grain yield/plant, and their heterotic values for the other
yield components were estimated. None of the top-ranking hybrids
were heterotic for all the traits simultaneously (Table 1). Standard
heterosis for grain yield/plant in the 212 crosses ranged from
-59.0-101.5 % with an average of 4.9 %. The cross WW-21/Raj3077
exhibited the highest performance for grain yield/plant (29.8
g) with a corresponding, highly significant positive standard
heterosis for grain yield/plant (101.5 %) and number of fertile
tillers/plant (96.1 %). The cross WW-21/RSP 303 was the second
best cross with standard heterosis values of 86.7, 92.3, and 52.1
%, for grain yield/plant, number of fertile tillers/plant, and
number of grain/spike, respectively. Interestingly, the third
best cross, WW-21/PBW-373, also involved WW-21 as the female parent
and exhibited significant positive standard heterosis values for
grain yield/plant (77.9 %), number of fertile tillers/plant (27.6
%), number of grains/spike (22.6 %), and 1,000-kernel weight (5.8
%). The lowest, negative, standard heterosis of -59.0 % for grain
yield/plant was recorded in the cross PBW-175/JOB-2028.
Based on a comprehensive 4-year study comprising 36 wheat hybrids,
Livers and Heyne (1968) reported that the F1 hybrids collectively
exceeded the parental lines with an average hybrid superiority
of 32.0 %. Wilson and Driscoll (1983) in their review of literature
on heterosis in wheat observed that the yield advantage of wheat
hybrids over the best check varieties over different locations
and years ranged from 4.1-31.0 %.
In summary, the results of this study showed that varieties
WW-21, Raj-3077, RSP-303, PBW-373, Blue Boy, PBW-343, RSP-81,
WW-19, UP-2425, and PBW-452 were the most promising parents, exhibiting
high standard heterosis for grain yield/plant and yield components
in some specific cross combinations. The results suggest that
these varieties could be utilized effectively in a wheat improvement
program with heterosis breeding.
Acknowledgments. Our thanks to G.S. Sethi, HPKVV, Palampur
(HP) and S.K. Nayar, IARI, Regional Station, Tuti Kundi, Simla
for supplying seed of the winter wheats.