Identifying morphological diversity and superior germplasm of Citrus reticulata Blanco (Mandarin) in Sikkim and Darjeeling Himalayas, India: an application of DIVA-GIS and cluster analysis

Abstract

Citrus reticulata is an important cash crop for the farmers in the Sikkim and Darjeeling Himalayas, India. The lack of knowledge of its diversity has only resulted in the lack of uniformity in the fruit quality. It has become imperative to identify superior varieties that meet the demands of the market to improve the citrus industry. Hence, a total of 105 accessions of mandarin were collected randomly from different locations to assess the morphological diversity using cluster analysis and DIVA-GIS. The orchards were randomly visited in each district of the state of Sikkim and two hilly districts of the state of West Bengal (WB). A sample tree was selected from each orchard and the quantitative and qualitative characters of its leaves, flowers, and fruits were measured. A significant variation was observed in the quantitative characters with a positive correlation between fruit weight and length, fruit diameter and weight, total soluble solids (TSS) /acidity and fruit diameter. The first 6 components of Principal component analysis (PCA) exhibited 69.34% of the total variation. DIVA-GIS showed the highest diversity index for fruit weight, fruit diameter and TSS/acidity in East district, Sikkim. The highest coefficient variation for fruit diameter was observed in the East district and Darjeeling district, WB and TSS/acidity and fruit weight in East district. The dendrogram generated divided the accessions into two major clusters. The grid maps generated identified diverse accessions in the East district and Darjeeling district, which can be a source of superior germplasm