Proceedings of the Fifth Asian Regional Maize Workshop - Search ...

EntQllOlogical research.
In the field of maize entomology, the stem borer (Chi7o parte7us) and the pink borer
(Sesamia inferens) have been identified as major pests. Keeping in view their importance, a
massive artificial infestation program has been in operation. Accordingly, a suitable methodology
for mass rearing these insect pests in artificial diet has been worked out which has proved
very effective. Also, a growth stage between 10-17 days after germination and about 25 larvae
per plant have been found to be appropriate in evaluation of maize germplasm for tolerance to
these borers. A 1-9 numerical rating scale has also been developed for categorizing the test
entries into resistant/susceptible classes, where a rating of 1-3 represents least susceptibility
and 7-9 highest susceptibility.
A reasonably good level of resistance has been identified in inbred lines derived from ETO
25, CUba 9, Barbados 1, SUWan Source 6, and H 207.
Pathological research.
In the field of maize pathology, a significant contribution has been made by AICMIP.
SUitable techniques of creating artificial disease epiphytotics in the field have been developed
for the most important maize diseases occurring in India. SUitable rating scales for' classification
of materials into resistant/susceptible categories have been developed. A high level of
resistance has been identified to several diseases based on field evaluation and an inventory of
resistant sources to major diseases has been released. In the case of turcicum and maydis leaf
blights durable resistance in two inbred lines has been detected. This resistance has stood for
almost 17 ears and at as many as 19 locations. Very encouraging reports about the stability of
this type of resistance have been received from other countries.
Chemical control schedules, wherever their economics have been worked out, have proved
very effective for the management of several foliar diseases. In the case of pythium stalk rot,
an integrated disease management strategy has been worked out. Similarly, for the management of
banded leaf and sheath blight a very effective and economic cultural method has been reported.
Biochemical investigations.
Since maize is used as a staple food in the form of chapatees, one of the problems faced
is the development of bitterness of the flour within a short period which leads to its unpalatibility.
This phenomenon is attributed to the hydrolytic rancidity which leads to accumulation of
acid. The problem can very well be overcome by giving heat treatment to the maize grains which
not only leads to inactivation of enzymes responsible for bitterness, but also minimizes moisture
content (Table 11).
Table 11. Effect of heat treatment of maize kernels (1 hr at 80 C) before grinding on shelf life
of maize flour.
Storage period
(days)
Acid value
Untreated Treated
o
2
10
20
30
0.9
12.7
23.2
27.7
33.2
1.0
1.1
2.4
2.4
2.7
Collaborative research projects.
Since 1992, six ICAR-eIMMYT Collaborative Projects in various facets of maize improvement
have been in operation. These are i) genetic resource, exploration, cataloging, and conservation,
ii) evaluation of inbred lines for more productive hybrids; iii) maize cultivation under
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