RA 00110.pdf - OAR@ICRISAT

Discussion
The discussion of the paper by Harinarayana centered
on the future of hybrid pearl millet cultivation
in India. I f the area under hybrids is to expand, will
there be sufficient infrastructure to support the
adoption of hybrids There was doubt about the
availability of irrigation needed for maximum production
from hybrids, especially in Rajasthan,
although the speaker said that hybrids did have a
place in certain agroclimatic zones, with certain
agronomic improvements.
There was some doubt about the relative productivity
of hybrids in research station trials and on
farmers' fields, but a number of hybrids, as well as
varieties such as WC-C75, HC 4, and synthetics such
as ICMS 7703, produce good yields on farmers'
fields.
The disease reaction of hybrids, particularly to
smut and ergot, the time and amount of pollen produced,
and the relative advantages of different types
of hybrids were discussed. The heterogeneity of multicross
hybrids could be an advantage in reducing
smut and ergot, but the literature is contradictory on
this point. The speaker said the contradictions were
due to changes in the composition of the mixtures,
the locations they were grown in, and other factors.
Pollen germinates faster and prior to the conidia of
the pathogen, so early pollination by the use of
mixtures of early and late flowering genotypes
deserves investigation. Heterogeneous populations
have shown less incidence of ergot or smut.
One scientist pointed out that the use of openpollinated
varieties is causing problems for seed certifying
agencies. There was discussion on the amount
of heterosis expressed in single-cross versus multiplecross
hybrids. At present the three-way cross hybrid,
M B H 118, has produced grain yields better than
those of the best single-cross hybrids.
In the paper by Spencer, hybrids were again discussed,
relative to conditions in Africa. Most of
what was said about West Africa also applies to East
Africa. There was a query whether the lack of
improved varieties is a major constraint, and whether
there is a potential for hybrids in Africa. The speaker
said that lack of improved varieties is not a serious
constraint to increased production, because improved
management with existing varieties could lead to a
substantially increased production. However, improved
varieties had an important role to play in the
future, and must be planned for now. If hybrids are
introduced, he said, they must have sufficient economic
advantage to pay for the necessary investment
in seed and infrastructure.
In response to a question whether low pearl millet
production was due to poor pricing policy or poor
systems of grain procurement, the speaker said that
poor pricing policy was often used as a pretext for
the poor performance of agriculture, but there was
no indication that the pricing and other policies for
millet have been any worse than for other food crops
in West Africa, and the explanation probably lies in
other technological and environmental factors.
The role of intercropping featured prominently in
the discussion. Millet is usually intercropped with
legumes, particularly cowpea, in West Africa. The
speaker was asked if intercropping was to be encouraged
in the Sahel, or whether a sole crop with
higher population density would also contribute to
increased productivity. Spencer said that many
experiments in the Sahel had shown that increased
density of millet, both sole and intercropped, yielded
higher, but intercropping still maintains its economic
advantages, and must be encouraged. Most of
the soils on which millet is grown are sandy and low
in nutrients, which may explain why intercropping
gave the best yields, but it was questioned whether
there will also be a good response to fertilizer. It was
confirmed that the response to phosphorous was
very good, but the response to nitrogen was poor.
The phosphorous trials were conducted in Niger
using traditional varieties, but improved varieties
could use the fertilizer more efficiently.
In the discussion on the paper by Hanna, the
comment was made that although triploids are usually
sterile, triploid interspecific hybrids in Arachis
had produced seed at ICRISAT Center, but did not
under the short-season conditions in the USA. If a
similar phenomenon occurred in pearl millet, the
progeny from triploids could be valuable in gene
transfer.
The yield increase in derivatives of wild species
was discussed. This yield increase was probably due
to a combination of genes from monodii which promote
vigor and yield, with the morphological characteristics
of the cultivated species, such as seed and
inflorescence size, and floret density. When asked
what part disease resistance played in this increased
yield, Hanna said that most of the increase was due
to the already mentioned yield components, but if
63