Assessment of phenotypic diversity in Tunisian carrot (Daucus carota subsp. sativus) landraces

Authors: BEN AMOR, JIHEN - Tunisian National Institute Of Agronomy; MEZGHANI, NAJLA - National Bank Of Genes; Spooner, David; HAMDI, KHAWLA - Tunisian National Institute Of Agronomy; GHEZAL, AICHA - Tunisian National Institute Of Agronomy; TARCHOUN, NEJI - Tunisian National Institute Of Agronomy

Submitted to: Journal of Horticultural Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2019
Publication Date: 12/3/2019
Citation: Ben Amor, J., Mezghani, N., Spooner, D.M., Hamdi, K., Ghezal, A., Tarchoun, N. 2019. Assessment of phenotypic diversity in Tunisian carrot (Daucus carota subsp. sativus) landraces. International Journal of Agriculture, Environment and Biorsearch. 4(4):75-91. https://doi.org/10.35410/IJAEB.2019.4409.
DOI: https://doi.org/10.35410/IJAEB.2019.4409

Interpretive Summary: Tunisia is a center of diversity of diversity for wild carrots. Knowledge of this diversity helps genebank curators and plant breeders choose germplasm for maintenance in the genebank, plan further collections, and to choose diverse germplasm for breeding programs. The main objective of the present work was to obtain knowledge of morphological diversity of 33 landraces of carrot from 13 different regions of Tunisia, based on 34 characters related to leaves and roots. A commonly used index of diversity, the Shannon-Weaver Diversity (H’) index was used to analyze the data gained in this study. This index ranged from a low of 0.19 for carrot core color to 0.99 for a measure of how much the leaves are finely divided. Another measure, analysis of variance, revealed significant differences among common farmer's varieties (landraces) for all quantitative characters. Another procedure, stepwise multivariate analysis was carried out to identify the best characters to distinguish among landraces, and it showed that the qualitative characters (that is, those that were scored as classes of characters, not actual measurements, were the best for the delimitation of landraces in this collection. The Tunisian carrot collection can be roughly divided into four groups independent of their geographic distribution. This information will be helpful to curators in the management and improvement of carrot germplasm in Tunisia.

Technical Abstract: Knowledge of the morphological diversity of a germplasm collection is fundamental for genebank managers and plant breeders. The main objective of the present work was to characterize 33 landraces of carrot from 13 different regions of Tunisia, based on 34 agro-morphological characters related to leaves and roots. The Shannon-Weaver Diversity (H’) index was used to study the phenotypic diversity. The estimated H’ ranged from 0.19 for core colour compared to cortex colour (RCCCC) to 0.99 for leaf division (LD). Analysis of variance revealed significant differences among landraces for all quantitative characters. Stepwise multivariate analyses were carried out to identify the useful characters that can distinguish among landraces. This study showed that qualitative characters were the best for the delimitation of landraces in this collection. Cluster analysis permitted the subdivision of carrot collection into four distinct groups independent of their geographic distribution. This information will be helpful to curators in the management and improvement of carrot germplasm in Tunisia.