MUNGBEAN VARIETAL IMPROVEMENT S. Shanmugasundaram

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are separated with a dissecting needle and the keel petals and anthers are carefully
removed. For pollination, a stigma covered wtih fresh pollen from dehisced
anthers is rubbed across the stigma of the emasculated flower and the standard and
wing petals returned into place. Emasculation in the evening and pollination the
following morning gives maximum seeds set. From 20 to 60% pod set has been
reported with this procedure (T.P. Singh and Malhotra, 1975; Park and Yang,
1978).
An improved technique was described by Cupka and Edwards (1986) in
which the tip of the bud is opened with fine tipped forceps to expose the style and
the stigma, and the anthers are slowly dislodged. After pollinating the emasculated
bud, a cellophane tape is placed over the opening to seal the bud and reduce
humidity and temperature fluctuations within the floret. Emasculation and
pollination can be accomplished in one minute with 60% success.
Breeding Methods
Mungbean is a self-pollinated crop and the breeding methods are those
commonly used with self-pollinated species. These are:
1. Collection of local cultivars, or introduction of promising cultivars or breeding
lines.
2. Pure line selection: Isolation of a superior pure line from a mixed seed lot is a
rapid and efficient procedure for obtaining a new cultivar.
3. Selection from hybrid progenies: Pedigree selection is generally practiced in
segregating generations following hybridization since individual plants are
easily identified and evaluated.
4. Multiple-parent crosses; Multiple-crosses are generally designed to combine
two or more useful genes from undesirable parents simultaneously into an
adapted germplasm.
5. Backcrosses; A desirable gene may be added to an adapted variety by a
succession of crosses using the adapted parent as the recurrent parent, or by
making each backcross to a different recurrent parent, a procedure termed
"modified backcrossing".
6. Repetitive intercrossing: Intermating for one or two cycles before starting
selection (Dahiya and Singh, 1985). As mungbean is a self-pollinating crop,
this is a labor-intensive procedure. Most early varieties were developed by pure
line selection from native germplasm. Currently, hybridization is the most
important breeding procedure. See discussion in Poehlman (1991).