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Hybrid Wheat
Global
Efforts
Generating
New Variability
Segregating
Stock Nursery
National
Genetic Stock Nursery
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Exploitation of heterosis through hybrid wheat is more attractive than the
conventional plant breeding methods due to lower yield gain of 1% per year in
North Western Plains Zone – the bread bowl of India. The traditional breeding
methods had so far exploited inter-genomic heterosis making it higher yielding
than other diploid crops however, the advantage of intra-genomic heterosis in
the three genomes can be harvested through the use of hybrid wheat. In India,
efforts on hybrid wheat were initiated in sixties following cytoplasmic male
sterility (CMS) approach however no significant results were obtained. In 1995,
Directorate of Wheat Research Karnal, had decided to re-address hybrid wheat
with an emphasis on chemical hybridizing agent (CHA) approach.
The opportunity to develop hybrid wheat therefore is highly relevant and rice
hybrid is a trendsetter. Unlike rice, in wheat the A, B and the D genomes came
together to form the hexaploid bread wheat (Triticum aestivum). Therefore
even after several years of efforts no real break through happened (Mahajan V
and Nagarajan S, 1998 Opportunities in Hybrid Wheat--A Review. Current Science
B64 No.1 pp51-58).
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Chemical
Hybridizing Agent Approach:
At the Directorate of Wheat Research,
Karnal the other option, namely the use of CHA was seriously considered. Here we
share our success and difficulties; as hybrids offer a great potential for
further yield advances and may permit us achieve the 109 million tons of yield
from less area under wheat.
Global
Efforts: In last 15 years significant efforts have been made for
commercial exploitation of hybrid wheat through the use of gametocide. Today,
France, Italy, South Africa, and USA have commercial wheat hybrids. In most of
these cases the hybrids have longer growth period so that they harness the
maximum biomass. After considerable discussion the target area for hybrid wheat
was identified as the irrigated, high fertility and timely sown conditions of
North Western Plains Zone (NWPZ) i.e. the bread bowl of India. This would ensure
more farm income to the farmers and at the same time relieve wheat area for
other crops as part of our efforts to diversify cropping system and achieve
sustainable wheat production.
GENERATING NEW VARIABILITY
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more Research Articles
Segregating
Stock Nursery: The
wheat-breeding programmes remain vibrant due to the availability of superior
genetic stocks for yield and other key characters. Directorate of Wheat Research
started constituting "Segregating Stock Nursery" in 1997 that includes
F2 generation of promising parents. This nursery every year is
supplied to ten up-coming centers, which are less exposed to new gene complexes.
Even though this nursery initially had the input of segregating material from
Hybrid Wheat Programme, it was later supported by leaf blight, late sown and
durum programme. Pre-breeding programme also joined in 1998-99 as a part of
hybrid programme.
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National
Genetic Stock Nursery :
A co-operative multi-locational evaluation programme of available wheat
germplasm in the form of National Genetic Stock Nursery (NGSN) was initiated in
1964-65 crop season and being continued since then. The nursery has been
improved each year by deleting not so promising stocks of previous years nursery
and addition of new promising material. The primary aim of this nursery is to
provide confirmed genetic stocks to the wheat breeders as well as it provides an
opportunity to evaluate the genetic stocks for agronomic superiority, biotic and
abiotic stress tolerance in various wheat growing zones through 35 centers
spread through out the country. The data so generated was published in the form
of Progress Report, Vol II, Genetic Resources every year (Mahajan 1997, 1998,
1999, Mahajan and Ganga Rao 2000, 2001,In
“Germplasm Evaluation and Enhancement” DWR publications).
Further refinement in NGSN
constitution has been made since 1996-97 crop season onwards. NGSN was
transformed into “Suggested Crossing Block” wherein confirmed sources for
various characters were included. The genetic sources were confirmed in various
other nurseries like Initial Plant Pathological Screening Nursery (IPPSN), Yield
Component nursery (YCSN), Short Duration Late Sown Nursery (SDN), Quality
Component Screening Nursery (QCSN), Drought and Heat Tolerant Nursery (DHTSN).
These nurseries introduced genetic stocks as confirmed sources along with the
supporting data. Testing over years and at number of locations generated the
data in these nurseries.
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