Genetic variability and correlations in nine divergent varieties of coconut
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Date
1998
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Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara
Abstract
An experiment was conducted at Instructional Farm, College of
Horticulture, Vellanikkara during 1995-96 on nine coconut varieties viz., West
Coast Tall x Choughat Yellow Dwarf, West Coast Tall x Gangabondam, Laccadive
Ordinary x Gangabondam.West Coast Tall, Philippines, Jawa, Cochin China, New
Guinea and Laccadive Ordinary, Significant varietal variance was absent among
several characters, Economic characters showed the highest genotypic coefficient of
variation (16 to 22%). Among the vegetative and reproductive characters,
heritability was maximum for petiole length (52%) followed by the economic
characters percent oil content and nut yield (45% each).
Among the four reproductive characters studied for seasonal variability
viz" spadix length (SL), branches spadix' (BS), female flowers spadix" (FF) and
fruit set (FS), FF showed the maximum variation, FF andFS had been low during
the rainy months, SL was markedly reduced during the winter months,
Phenotypic correlation coefficients were generally lower than genetic
SInce environmental correlation was either less in magnitude or in opposite
direction in relation to the genetic, Genotypic correlations were mostly negative
where vegetative characters were involved and positive for other pairs, Only nut
yield among the four economic characters was correlated with both vegetative and
reproductive characters, Other economic characters were dependent only on
vegetative characters. Similarly step-down regression revealed that only vegetative
characters were retained in the final model for all the economic characters except
nut yield.
Vegetative characters also showed higher direct effects than reproductive
characters on the variability of economic characters. Trunk height generally
produced highest direct effects on the economic characters, but was modified by the
indirect effects to large extent except in the case of oil content (%).
Correlation, regression and path analyses suggested that reproductive
characters had less effect on economic characters when all the characters were
recorded during the 'same year. This may possibly be due to genotype x season
(year) interaction for the reproductive characters.
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PG
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Citation
171392