Morphological Identification of Mandarin (Citrus reticulata Blanco) in Bhutan

This study aimed to identify Bhutanese mandarin accessions using morphological characteristics. A total of 30 accessions were selected from six districts in the major mandarin-growing regions in Bhutan. Samples of 15 leaves, 5 flowers and 15 fruit were collected randomly from each accession. A total of 23 characters were evaluated from the trees, leaves, flowers and fruit from each plant. A dichotomous key constructed from the morphological qualitative characters was able to classify the accessions to the district level. There were statistically highly significant differences (P < 0.01) for leaf length, leaf width, fruit weight, fruit diameter, fruit length, epicarp width, number of seeds and total soluble solids (TSS). The floral morphology showed little variation among trees and districts. The accessions from Dagana had the highest fruit weight with 107.2 g followed by Samtse, Zhemgang, Sarpang, Trongsa and Tsirang with fruit weights of 96.1, 93.3, 87.6, 78.9 and 58.3 g, respectively. The highest TSS were found in the accessions from Trongsa (12.9 °Brix) followed by Zhemgang (12.1 °Brix), Dagana (11.2 °Brix), Sarpang (10.9 °Brix), Tsirang (10.6 °Brix) and Samtse (10.3 °Brix). Accessions from Samtse were early maturing (mid October) while accessions from Tsirang were late maturing (February–March).