PhD

Variability in banana are wide and complex with different degrees of
expression of the characters of the parental species, Musa acuminata and
Musa balbisiana. Commercial cultivars are many, ranging in levels of
productivity and quality characters. Investigations were conducted at the
College of Horticulture, Kerala Agricultural University, Vellanikkara, Trichur
during 1981-83 on 100 cultivars of banana to study the cytotaxonomical
aspects.
Studies
on
morphological
characters,
taxonomic
scoring
and
chromosome number revealed that many of the cultivars were identical and
ultimately the cultivars were confined to 64 distinct ones. The taxonomic
scoring did not indicate the ploidy. Eight cultivars with the scores of triploids,
were identified as diploids.
The quantitative, quality and pollen characters showed a significant
variation among the cultivars. The characters were influenced by the ploidy
and the genomic constitution. The presence of ‘B’ genome increased plant
height and girth, leaves per plant, leaf area per plant and petiole length. Musa
balbisiana (BB) recorded the highest values for all the above characters.
The triploids were more vigorous than the diploids and the tetraploids
as indicated by their higher growth rates. The triploids were also better than
the other groups for bunch and finger characters. Among them, the triploids
of hybrid origin were better for bunch characters while the Musa acuminata
triploid group (AAA) was superior to the other groups for finger characters.
Longer pedicel was a characteristic feature of Musa balbisiana( BB).
The genomic constitution of the cultivars influenced the contents of
total soluble solids, sugars and acids in fruits, more than the ploidy. Musa
acuminata group AAA, had the highest sugar/acid ratio.
Studies on pollen viability, size and production in cultivars revealed the
possibility of including a few of them as male parents in the banana
hybridization programme. Forty of the cultivars studied were polleniferous.
Pollen viability and production were more in pure Musa acuminata and Musa
balbisiana groups than in groups of hybrid origin. Musa acuminata cultivars
had larger pollen grains than cultivars belonging to the other genomic groups.
Estimates of genotypic and phenotypic coefficients of variation, heritability in
the broad sense, genetic advance and genetic gain for the 26 characters
indicated the scope for selection among the cultivars. Petiole length, pulp/peel
ratio on volume basis, weight and volume of fruit showed higher heritability
values combined with high genetic gain.
Estimation of genetic divergence among the cultivars showed that the
cultivars ‘Mannan’ and ‘Pacha chingan’, belonging to the genomic group
AAB, were the closest and a Musa acuminata cultivar, ‘Harichal’ (AAA) and
Musa balbisiana (BB) were the farthest. The 62 cultivars were grouped into
eight homogeneous clusters. Similar clustering pattern was obtained in the
canonical analysis also.
The study revealed the predominance of the cultivars of the hybrid
origin, with different degrees of expression of the characters of the parental
species, in the South Indian bananas. The taxonomic scoring system was not
always appropriate to find out the ploidy of the cultivars. The study also
indicated the scope for selection among the cultivars and the possibility of
inclusion of the cultivars with viable pollen as male parents in the
hybridization programme.