GENETIC DIVERSITY OF WILD WALNUT (Juglans regia L.) POPULATION IN HIMACHAL PRADESH
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Date
2024-03-18
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UHF Nauni
Abstract
The present investigation entitled “Genetic diversity of wild walnut (Juglans regia L.) population in
Himachal Pradesh” was carried out in the Department of Tree Improvement and Genetic Resources, Dr Y. S.
Parmar University of Horticulture and Forestry, Nauni, Solan (H.P.) during 2020-2024 and employed a
multidimensional approach encompassing morphological analysis, wood characterization, nursery progeny
evaluation, and molecular marker studies. To investigate genetic diversity, walnut genotypes were carefully
selected from 12 distinct sites across Himachal Pradesh. The genotypes were categorized based on both latitude
and altitude ranges. Wood samples from these diverse sites underwent thorough physico-chemical analysis. The
seedlings were raised in polybags in an experimental field and assessed using a Randomized Block Design. This
genetic material was utilized for investigating the spectrum of diversity via molecular markers. Morphological
studies revealed a wide range of characteristics among the genotypes, including tree height, crown dimensions,
leaflet and nut traits. Notably, all nut and leaf traits exhibited high heritability and significant genetic advance,
indicating the potential for efficient selection based on additive gene action. Correlation studies unveiled
significant relationships between various morphological attributes and geographical parameters such as latitude
and altitude. Principal Component Analysis (PCA) revealed three principal components contributing to
variability in tree, leaf and nut characteristics. In the genetic divergence investigation, the genotypes were
classified into three primary clusters, with the majority falling into Cluster-III. Cluster analysis emphasized
distinctive characteristics within each cluster, providing valuable insights into the diversity among wild walnut
genotypes. Wood analysis across different genotypes revealed varying physico-chemical traits, with certain
genotypes exhibited notable properties such as high moisture content, specific gravity, and fibre length.
Correlation studies in wood analysis demonstrated significant relationships between certain attributes, offering
valuable information for wood quality assessment. The evaluation of nursery performance showcased significant
variations in germination and survival percentages, seedling height, collar diameter, and leaflet measurements
among different genotypes and between sites. Traits like seedling height and collar diameter displayed high
heritability and significant genetic advance, suggesting their suitability for genotype selection. On the basis of
principal component analysis of nursery traits, the 1st two principal components (PC’s) possessed Eigen value
>1.0 explained 65.29 per cent of the total variance. Molecular characterization using SSR primers identified
genetic diversity among the walnut genotypes. 20 SSR primer pairs were used to assess genetic diversity among
52 walnut genotypes. Eighteen primers consistently amplified, yielded 43 distinct alleles, with 11 primers
displayed 100 per cent polymorphism. The UPGMA dendrogram grouped the genotypes into two distinct
clusters, providing insights into their genetic relationships. In conclusion, this comprehensive study provides a
detailed assessment of genetic diversity in wild walnut populations in Himachal Pradesh. The multidimensional
approach, incorporating morphological, wood characterization, nursery performance, and molecular marker
analyses, offers valuable insights for the conservation and improvement of this economically important tree
species. The findings serve as a foundation for further research in walnut breeding and genetic resource
management.