RA 00015.pdf - OAR@ICRISAT

Whole-seed Protein vs. Dhal Protein
For rapid screening it would be desirable to use
ground samples of whole seed; preparation of
dhal of many small samples is tedious and timeconsuming.
We determined the protein content
of dhal and whole-seed samples of 43 cultivars
using the M K J technique, and found a correlation
of r = + .94 (Fig 34). The same samples
by T A A gave a correlation of r = + .97, and
with the DBC method r = +.88. It was concluded
that for rapid screening, whole seed rather
than dhal samples could be analyzed.
Errors of Determination of Protein
In order to establish reliable procedures for
comparing protein content of different pigeonpea
lines, we conducted an experiment to compare
sources of error. Seed of 10 cultivars grown
in three replicates were sampled twice, and these
subsamples were each analyzed twice by T A A .
The experiment was repeated on 2 different days
in the laboratory.
The experimental error (random variations
among cultivars in different replicates in the
field) was the most important source of error. It
was three to four times as large as error due to
sampling within seed lots or determination error
in the laboratory. The results indicate that
reliable estimates of genetic differences in protein
cannot be made on individual plants or plots
because of interaction with the environment.
However, with the three replicates used, it was
possible to identify small differences among
cultivars.
Sulphur Amino Acids and Tryptophan
Protein quality of pigeonpea is determined in
part by the limiting amino acids. Pigeonpea seed
protein is normally low in methionine, cystine,
and tryptophan. Microbiological assays for the
estimation of sulphur amino acids and the use of
the Leco sulphur determinator for the estimation
of total sulphur in pigeonpea samples are being
tried, in order to understand whether the total
sulphur determination would be an indirect
useful way to screen for sulphur amino acids.
Two colorimetric methods for the estimation of
tryptophan are being evaluated for rapidscreening
purposes.
Composition of Some Pigeonpea
Cultivars
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27
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r = + 0 . 9 4 * *
4.428 + 0.939 x
Ten released cultivars of pigeonpea were analyzed
for protein, starch, soluble sugars, fat,
crude fiber, and ash contents (Table 33). Protein
content ranged between 23 to 27.3 percent,
whereas starch percentage ranged between 56.3
to 64.1. Fat, crude fiber, and ash contents ranged
between 1.2 to 2.2, 1.0 to 1.2, and 3.3 to 4.3
percent respectively.
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International Cooperation
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19 20 21 22 23 24
Whole-seed p r o t e i n percent ( N x 6.25)
figure 34. Relationship between whole-seed protein
and dhal protein in pigeonpea by
MKJ method.
We are maintaining a close liaison with pigeonpea
breeding programs in India and in other
countries. We furnish detailed annual reports of
our various disciplines to cooperating scientists
to keep them abreast of developments prior to
formal publication of our results. We also furnish
breeding material; 21 breeders from 8
countries were supplied segregating populations
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