Characterization of cinnamon (Cinnamomum verum Presl.) Accessions

Abstract

Cinnamon assumes considerable importance among the perennial spices of the world as one of the most extensively used spices in the food and beverage industries. The commercial form of cinnamon is derived from the dried inner bark of the Cinnamomum verum Presl., a member of the Lauraceae family. Sri Lanka has a unique identity I producing the world’s finest quality cinnamon. In India, Meghalaya is the primary producer, though Meghalaya predominantly contributes tejpat (Cinnamomum tamala Th. Nees & Eberm) Kerala ranks sixth in the contribution of true cinnamon, making up 0.17 per cent of the total national production. The present study entitled “Characterization of cinnamon (Cinnamomum verum Presl.) accessions” aims to systematically examine the morpho-biochemical characteristics and evaluate the yield of cinnamon accessions grown in the high-altitude region (AEU 21) of Kerala. The study was based on cinnamon accessions of seedling origin conserved as ex-situ at the Regional Agricultural Research Station, Amabalavayal. These accessions aged about 25 years were collected from various cinnamon-growing regions and maintained through regular coppicing. A single tree represents each accession. The morphological characterization of 21 qualitative and 16 quantitative characters from the selected accessions were recorded. In the biochemical characterization, volatile oil and oleoresin from dried bark and fresh leaves from all fifty accessions were analysed. Chemical profiling of bark volatile oil was performed for superior cinnamon accessions. A modified minimal descriptor for cinnamon with a set of 21 qualitative parameters as well as descriptor states for each character was developed as the first step of the study, referring to the previous work (Krishnamoorthy et al., 1996, Azad et al., 2019 and Liyanage et al., 2020). The developed minimal descriptor for cinnamon was further subjected to the characterization of cinnamon accessions. A wide variability was further subjected to the characterization of cinnamon accessions. A wide variability was observed for 13 out of 21 qualitative characters. The study revealed that, 7 out of 11 leaf characters; 3 out of inflorescence and floral characters; all four bark characters showed variability in the cinnamon accessions. However, no variation was observed in the fruit characters. Overall, eight qualitative characters were noted as non-variable characters; hence, these were not considered for further analysis. Based on the 13 qualitative variables, accessions were delineated into four discernible clusters at a scale height nine. In the present study, considerable variation was observed among the cinnamon accessions for most of the quantitative characters. The maximum coefficient of variation was observed for inflorescence length (41.72%). Quantitative characters, viz., number of shoots per stump and dry weight of quill, were found to record more than 30 per cent of coefficient of variation. Characters recorded more than 20 per cent coefficient of variation were fresh weight of quill, leaf area, dried bark thickness, plant height, leaf oleoresin and bark volatile oil. The quill dry weight varied among the accessions and ranged from 26.50 g (Acc.20) to 103.00 g (Acc.34) per coppice. The Principal Component Analysis (PCA) distinguished the distribution of quantitative characteristics into two dimensions. The first two principal axes (Dim.1 and dim. 2) explained 49.40 per cent of the total cumulative percentage of variance. The contents of volatile oil (0.35 to 1.10%; 0.5 to 2.05%) and oleoresin (7.30 to 19.40%;1.65 to 7.75%) differed significantly in both bark and leaves of cinnamon accessions, respectively. The association study through Pearson’s correlation coefficient method revealed that the fresh weight of the quill was found to have a positive and significant correlation with the dry weight of the quill, plant height, and mean firth of the coppice. Meanwhile, dry weight of the quill was found to be positive and significant with the fresh weight of the quill, plant height, bark recovery, and mean girth of the coppice. Fifty selected cinnamon accessions were ranked based on the four key yield and quality parameters namely, number of shoots per stump, bark recovery, dry bark yield, and bark volatile oil, which have a direct effect on economic importance. Subsequently, five cinnamon accessions, viz., Acc. 12, Acc. 28, Acc. 34, Acc. 39, and Acc. 56, were identified as superior performing accessions and further subjected to chemical profiling using the GC-MS technique. About fifteen constituents were identified through the analysis of bark volatiles using GC-MS. Cinnamaldehyde was a prime constituent present in cinnamon bark oil. Of the five accessions, cinnamaldehyde was present in four, and content ranged from 27.77 (Acc.28) to 40.32 (Acc.56) per cent. The Acc. 12 was dominated by linalool (34.35%). The cinnamyl acetate was predominant in all five accessions. The PCA revealed the distribution of biochemical constituents among the different principal components. Which was mainly focused on the first two principal axes (Dim. 1 and Dim. 2, constituting 86.50 per cent of the total cumulative percentage of variance. From the study considerable variation was observed between the accessions for the morphological and biochemical characters. Based on yield, its components and other quality parameter, five promising accessions were identified. These accessions varied significantly for organic acides and had high cinnamaldehyde as well as unique in linalool content. These genotypes may be targeted for further genetic improvement or be utilized in selection method of breeding programme for developing high yielding cinnamon varieties which is also rich volatile constituents for high altitude tropical conditions.