MSc

The research project 'Genetic Analysis in F2 and F3 Progenies of
Selected Crosses of Rice Varieties of Diverse Origin' was carried out in the
College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur
durinq the period January to December, 1998. The major objectives of the
study were to understand the various genetic parameters of characters
under study, identification of yi&ld components and formulation of selection
model so as to isolate promising lines having desirable ideotypic features
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from the segregating generations. The high yielding varieties developed
from such lines will have a broad genetic base as the parents of selected
crosses are of diverse origin.
Components of heritable variation revealed that the characters
showed decreased trend of variability from F2 to F3. PCV was higher than
GCV in both generations for all the characters studied. Low PCV and GCV
were observed for grain length, panicle length and duration to 50%
flowering in both generations, while grain density showed low PCV and
GCV in F3 only. In general, broad sense heritability estimates were observed
to be higher in F2 than F3. The characters, plant height at harvest, total
tillers plant", LIB ratio, 1000 grain weight, secondary branches panicle' and
tertiary branches panicle:' provided great help in direct selection from
phenotypic performance, as they exhibited higher values of genotypic
coefficient of variation, heritability and expected genetic advance. The

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character, grain length showed little scope of improvement through
selection due to low GCV and GA .
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Correlation studies in F2 and F3 revealed that positive correlation
existed between yield and component characters, namely, total tillers,
panicle bearing tillers and tertiary branches panicle". Negative correlation
was observed for 1000 grain weight with yield in both the generations.
Panicle length and duration to 50% flowering exhibited absence of
association with yield in F2 and F3, which indicate that these traits can be
recombined as desired. In F3, LIB ratio and grain length exhibited positive
correlation and grain breadth exhibited negative correlation, with yield, while
these characters showed absence of association with yield in F2• Plant
height and number of grains panicle:' exhibited negative association with
yield in F2 where as number of grains panic!e' exerted positive association
with yield in F3 and plant height showed absence of association with
yield in F3.
Genotypic correlation among di~ferent yield components in F2 and F3
revealed that semidwarf plants with higher number of productive tillers
produced grains with higher LIB ratio and lesser grain weight, which in turn
increased the yield. The study also showed that, when number of grains
and compactness of• panicles increase, grains become more slender with
reduced grain weight.
Study of path coefficient analysis revealed that all the characters
influenced the yield directly or indirectlv through some other traits. The
correlation and path analysis study suggested that during selection, breeder

should give emphasis on" semidwarf olant stature, higher number of
productive tillers, compact panicles, reduced number of secondary
branches, high LIB ratio of grains with reduced density and weight.
A selection model was formulated consisting of the characters,
, namely, yield ha:'. total tillers plant". LIB ratio, grain breadth and
grain density. Using this model, ranking of 105 genotypes in F3 was
done and identified that the accessions, V 82 and V 89' belonging to
lA 36 x Mattathriveni, were the best genotypes. Study revealed that all the
four crosses namely, Vytilla 3 x Mattathriveni, Vytilla 3 x Kaohsiung Sen
Vu 338, Mattathriveni x Mahsuri and lA 36 x Mattathriveni, were promising
enough to derive superior segregants, the best among them being
IR 36 x Mattathriveni.
The plants with red kernel, identified in F3 of the cross IR 36 x
Mattathriveni, can be used for the development of high yielding varieties
with red kernel and preferable cooking qualities suited to Keralites, as well
as resistance to biotic and abiotic stresses. This investigation also suggested
that crosses from parents of diverse origin will broaden the genetic base of
the varieties to be developed in future and will help to break the yield
plateau in rice.