Oilseed brassicas, also known as
rapeseed-mustard, are among the largest traded agriculture commodities. India’s
combined volume of exports of rapeseed – mustard seed oils is almost 10.07% of
the total vegetable oilseeds. Growing importance and consequent research
investments have led to dynamic breakthroughs in yield and seed quality.
Modification of the seed oil and reduction of meal glucosinolate content by
Canadian breeders in rapeseed during the early 1970’s was a great plant breeding accomplishment that
stands next only in importance to the agricultural modification in cereals.
Since then, enormous strides have been made. Hybrids have been commercialized,
and all crop Brassica genomes were sequenced. World output of rapeseed
mustard crops rose from about 36 million tonnes in 2001-02 to 67.9 million tons
in 2015-16 (www.fas.usda.gov.in).
However the demand for rapeseed-mustard oils continues to escalate steeply due
to increasing consumption and diversion of bioenergy use.
India has traditionally been a Brassica
growing country where it has been under cultivation since atleast 3rd
millennium BC. The oleiferous Brassicas including B. juncea (L.)
Czern & Coss, B. rapa L., and B. napus L. are important
source of edible oil in India as rapeseed-mustard crops include toria (B.
rapa L. var. toria), brown sarson (B. rapa L. var. brown sarson),
yellow sarson (B. rapa L. var. yellow sarson), Indian mustard B.
juncea (L.) Czern & Coss, black mustard (B. nigra) and
taramira (Eruca sativa/vesicara Mill.) species. These along with
non-traditional species like gobhi sarson (B. napus L.) and karan rai (B.
carinata A. Braun) have been recorded to be grown since ancient time. Among
Brassicas, Indian mustard or Brassica juncea occupies around 90%
of the total rapeseed mustard cultivated area and 80% production (Singh et
al., 2008). It ranks second after groundnut in oilseed crops. Mustard oil
which was extracted from seeds is used for cooking media as well as industrial
purposes. The seeds are used as spices in the preparation of pickles, curries,
sauces and salad. Mustard tender leaves are also used for culinary purposes.
The mealed cake is used as cattle feed and seeds have medicinal properties. In
Northern India, mustard oil is mainly utilized for human consumption (Vaghela et
During the last decade, the yield of
mustard in India is almost static, hovering around 1-1.2 tonnes/ha, which is
much below than the world’s average of 1.98 tonnes/ha. The recent data showed
that with total area of 6.32 mha, India only able to produce 7.39 mt with
productivity of 1170 kg/ha (Agriculture Statistics at Glance, 2016). The world
acreage 2144 kg/ha and highest average yield 3640 kg/ha by European Union
indicates that India has to fill the
large gap of 85% over world acreage and 213% over European Union (www.nmoop.gov.in)
where tapping heterotic potential of crop through hybrids essentially leads to
In past, some improvements in the
genetic potential of the varieties have been obtained with the use of
conventional breeding methods like mass selection, pure line selection,
disruptive selection and inter-varietal hybridization. But the selection and
reselection were extensively followed in the low yielding local land races, and
progenies of hybrids. As a result the rate of increase in yield per unit area
has been slow. The yield level has almost reached a plateau in these crops.
This necessitated a change in breeding strategies in Indian
mustard and significantly yield improvement can be achieved through development
of commercial hybrids.
phenomenon of heterosis has been proved to be the most important genetic tool
in enhancing yielding potential in self as well as cross pollinated crops. In
India, efforts to develop F1 hybrids in Brassica though initiated
earlier were intensified subsequent to start of ICAR project on ‘Promotion of
Research and Development Efforts on Hybrids in Selected Crops’ in 1989. The
high parent heterosis for seed yield from Indian × Exotic crosses were reported
to average 55% with range of 30 to 90% by Pradhan et al (1993). In
contrast, high parent heterosis for oil and protein content is rarely
encountered in hybrids in Indian mustard varieties. These were produced by hand
emasculation and pollination which is not economical for production of hybrid
seed at large scale, therefore, number of CMS systems have been developed for
exploitation of heterosis which is only alternative to the increase the yield
level. Up to now, a lot of rapeseed CMS lines have been
developed, of which, Ogura (ogu) CMS shows very stable and complete
sterility (Falconer and Mackey, 1977). Development of hybrids requires studies
on the parental lines particularly of seed production characteristics not only
for its own maintenance but also for large scale hybrid seed production.
Keeping this in background, it was thought to analyze the cytoplasmic effect of
CMS on level of heterosis and combining ability between different lines and
comparing the heterosis as well as combining ability with euplamic hybrids.
Assessment of hybrid vigour is an important tool for
making genetic improvement in yield and its attributing characters in Indian
mustard. The magnitude of heterosis provides a basis for evaluation of genetic
diversity and a guide for the choice of desirable parents for developing
superior F1 hybrids to exploit hybrid vigour and for building gene pools to be
employed in breeding programme. Indian mustard is largely a self pollinated
crop which provides immense scope for the exploitation of hybrid vigour which
in turn depends on the direction and magnitude of heterosis and biological
Combining ability analysis offers an opportunity to
identify superior parents, which in combinations would provide desirable
segregation or may be hybridized either to exploit heterosis or to accumulate
Promising F1’s can directly be included in
evaluation trials, while others exhibiting heterosis for one or other desirable
traits may be advanced further to obtain transgressive segregants.