MUNGBEAN VARIETAL IMPROVEMENT S. Shanmugasundaram

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Pod Tip: Sen and Ghosh (1959) reported that a dominant gene controlled
the swollen pod tip over tapering pod tip.
1960).
Seed Size: Small seed size is dominant to large seed size (Sen and Murthy,
Seed Coat Surface: Bose (1959), Sen and Ghose (1959), and van Rheenen
(1965) reported dull, rough seed surface is a monogenic dominant over glossy,
smooth seed surface. Sen and Ghosh (1959) identified a second dominant gene
that governs dull, rough seed coat. Dull seeds are covered by an inner pod
membrane that renders the seed dull; when this membrane is removed the seed
coat underneath is shiny (Watt et al., 1977). The pod membrane may contain
brown or black pigment through which the seed coat color may not be apparent.
Based on this infounation, inheritance of pigmentation in the seed coat that may
have been reported earlier for seeds covered with the membrane needs to be
reevaluated. With a translucid membrane the seed coat color is visible through the
membrane layer (see Poehlman, 1991, for discussion).
Genetics, Quantitative Characters
Many traits of economic importance are inherited in a quantitative fashion
and their expression may be affected by both genetic and environmental
influences. The extent of the genetic variability of a quantitatively inherited trait
and the manner of its inheritance deternines its usefulness in plant improvement.
Genetic Variability
In mungbean the range of genetic variability for characters of economic
importance has been studied for large collections of accessions by Banks (1958),
Bhargava et al. (1966), K.B. Singh and Malhotra (1970a), Yohe and Poehlman
(1972), Virmani et al. (1983), Paroda and Thomas (1988), He et al. (1988), and
Sandhu et. al. (1988). In general, the. variability is reported to be sufficiently
extensive for progress in mungbean breeding programs.
Relationship of Plant Characters and Yield
A knowledge of the relationship among plant characters is useful when
selecting traits to combine for yield improvement. Correlation coefficients of yield
vs. some major yield associated characters are summarized in Table 3. The yield
component with the largest and most consistent correlation coefficient in a wide
array of experiments is pods-per-plant, a close positive relationship to yield being
reported in all experiments. Although a larger number of seeds-per-pod and higher
100-seed weight can compensate for low pod number, the association of seedsper-pod
or 100-seed weight with yield is inconsistent in different environments
and has low reliability as a selection criteria for yield.