Shallot Species and Subtypes Discrimination Based on Morphology Descriptors

Abstract

Shallots are an edible Alliaceous crop representing a group of genetically and morphologically different species. Shallot species determination is rather complex due to the high variability in phenotypes within a single species. Flower morphology has been successfully employed in shallot species determination; however, shallot florogenesis depends upon many genetic and environmental factors. There is a need for more accessible morphological descriptors used in shallot species determination, since flowering in shallot may not be consistent. In this study, we investigated the discriminating power of shallot vegetative and bulb morphology descriptors. European Cooperative Programme for Plant Genetic Resources morphology descriptors were used for describing 35 Croatian shallot accessions. The proposed methodology based on vegetative and bulb morphological descriptors could be used for shallot species discrimination. Additionally, two subtypes of A. cepa Aggregatum group were identified in this study: the first being the shallot type (1) and a potato onion type (2), which differed based on bulb morphology descriptors (bulb shape, bulb skin color, and a number of bulblets).

Effects of seed soaking with plant growth regulators combination on the aggregation ability of shallot from seeds

“…This is attributed to the relatively modest increase in the number of bulbs, with only 1.63 bulbs per plant compared to the control's 1.08 bulbs per plant (51%) (Table 4), which did not substantially impact the reduction of bulb size. Categorically, shallots are classified into two bulb shapes: slightly oval/ovate bulbs and broad oval shapes, with variations between the two (Perković et al, 2021). The 'Tuk Tuk' shallot bulbs shape tends to be round, with a height-todiameter ratio ranging from 1 to 1.1 (Table 5).…”

The Phytochemical and Nutritional Composition of Shallot Species (Allium × cornutum, Allium × proliferum and A. cepa Aggregatum) Is Genetically and Environmentally Dependent

“…Additionally, two subtypes of A. cepa Aggregatum were identified, the A. cepa Aggregatum PO type and the A. cepa Aggregatum SH type. The A. cepa Aggregatum SH type is characterized by an ovate bulb shape and yellow skin color, compared to the broad oval shape and light violet skin color of bulbs of the PO type [ 17 ]. In this research, we extended the number of shallot landraces to 34, conducted the experiments over two consecutive harvest years, and included additional biochemical and nutritional parameters to build upon the findings presented in our previous work [ 22 ].…”

“…In the years 2018 and 2019, 34 shallot accessions belonging to the ex situ collection of the Institute of Agriculture and Tourism were planted at the Institute’s experimental farm. The procedure was described by Perković et al [ 17 ]. Briefly, bulbs of a standard size were chosen for each accession and planted at the beginning of October at a distance of 20 cm in rows with 30 cm between rows, and 40 bulbs in total were planted for each accession.…”

“…× proliferum ) and Allium × cornutum Clementi ex Vis., respectively [ 16 ]. The A. cepa Aggregatum group is the most cultivated shallot species in Europe and, based on their morphological traits, can be categorized into two subgroups: one has narrow, pear-shaped bulbs (Shallot type—SH), making it distinguishable from the other, which has rounder bulbs (Potato onion type—PO) [ 15 , 17 ]. The categorization into these two groups seems quite simple, being based on the morphological bulb traits, but the great biodiversity of the A. cepa Aggregatum group is responsible for the occurrence of many intermediate types of varying bulb size, shape, and number of clusters [ 18 ].…”

“…We build upon our previous work [ 22 ] by increasing the number of accessions studied, including two harvest years’ worth of data, and by expanding the list of analytical methods used to map the phytochemical biodiversity of the shallot accessions. Additionally, we also build upon the work by Perković et al [ 17 ], where shallot morphological descriptors were used to successfully discriminate between various shallot groups, including the differentiation of the A. cepa Aggregatum SH and PO subgroups.…”