Characterization of genetic diversity in onion (Allium cepa L.) using agro-morphological and molecular markers
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Date
2022-12-19
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CSK HPKV, Palampur
Abstract
The present investigation was undertaken to estimate the genetic parameters of variability, associations
among marketable bulb yield and contributing traits and characterize the onion genotypes using agro morphological and molecular markers. The experimental material comprised of 49 genotypes including two
checks ‘Palam Lohit’ (red) and ‘Him Palam Shweta’ (white) that were evaluated in Randomized Complete
Block Design (RCBD) with three replications during rabi season, 2020-21. Sufficient genetic variability was
observed among the genotypes for all the traits under study. Based on mean performance, genotypes CITH-0-
2 followed by PRO-8 and ON20-30 in red category and ON20-74 in white category were best performing for
marketable bulb yield. These genotypes were also found to be promising for other traits viz., plant height,
leaves/plant, bolting percentage, equatorial diameter, average bulb weight, biological yield, total bulb yield,
pyruvic acid, protein, nitrogen, phosphorus, zinc, boron, stemphylium blight incidence percentage and thrips
incidence percentage. High PCV and GCV along with high heritability and high genetic advance were
observed for bolting percentage, A grade bulbs, D grade bulbs, double bulbs, total sugars, zinc, manganese
and sprouting percentage indicating that selection on the basis of these traits would be effective. A significant
and positive correlation was found between marketable bulb yield and average bulb weight, total bulb yield,
biological yield, equatorial diameter, polar diameter, plant height, neck thickness, A grade bulbs, leaves/plant
and moisture content while total losses with rotting percentage, potassium, total sugars, sprouting percentage,
manganese, copper and sulphur. In view of direct and indirect contribution of component traits, selection on
the basis of total bulb yield, average bulb weight and D grade bulbs would be paying preposition for evolving
high yielding genotypes and their improvement. The study revealed considerable genetic diversity among
genotypes which were grouped into seven clusters (horticultural basis) and ten clusters (quality basis).
Principal component analysis revealed that total 81.84 per cent variation was contributed by first six
components. Genetic divergence study using UPGMA (NTSYS) with molecular markers divided the
genotypes into two clusters. Sixteen genotypes were found to be common on comparing agro-morphological
and molecular clusters demonstrating the congruence between morphological and ISSR data among which 12
were red onion viz., ON20-47, ON20-45, ON20-50, ON20-51, CITH-0-2, VL Piaz-3, Sona, Sandeep, ON20-
41, PRO-9, Bhima Shakti and NHO-920, whereas four were white onion viz., W-355, Agrifound White, W 340-EL-8 and DOGR-HT-4. Thus, from the present investigation it can be concluded that three genotypes
from red onion viz., CITH-0-2, PRO-8 and ON20-30 while two genotypes from white onion viz., ON20-74
and DOGR-HT-2 were found to be the most diverse and can be directly used after multi-location testing as
they posess inherent ability to produce high yields and have superior quality traits or can also be used in
breeding programmes to exploit heterosis or to isolate transgressive segregants with desirable traits.