Morphological characterisation of jasmine (Jasminum spp.)

Abstract

Jasmine is one of the oldest fragrant flowers cultivated by man, which belongs to the family Oleaceae. Although there is high demand for jasmine in Kerala for different occasions, large-scale cultivation is not common. It is crucial to assess the accessions for their characters that will aid in choosing the best genotype for commercial cultivation and crop improvement. In this context, the present study “Morphological characterisation of jasmine (Jasminum spp.)” was undertaken with the objective of evaluating jasmine accessions by using various morphological characters. The experiment was conducted in the Department of Floriculture and Landscaping, College of Agriculture, Vellanikkara from Oct 2021 to Nov 2022. A total of twenty one accessions, including seventeen accessions maintained by AICRP on Floriculture, Kerala Agricultural University and four accessions collected from various parts of Malappuram and Thrissur district were utilised for the study. Morphological characters, viz., plant growth, leaf, floral and post-harvest characters were evaluated in the twenty one accessions. The study revealed significant differences among the accessions for almost all the characters. The jasmine accessions exhibited two types of plant growth habits: bush and climber. Out of twenty-one accessions evaluated, a comparatively large number (eighteen) of accessions were observed to be bushy. Plant height, number of primary and secondary branches also varied among the accessions. Pigmentation in young shoots was recorded in Jasminum nitidum accession KAU Jn 1 and TNAU Jn 1, and Jasminum sambac accessions KAU Js 3 and KAU Js 5. Seventy-six per cent of jasmine accession exhibited simple leaf type. In the remaining twenty-four per cent, pinnately compound and trifoliate compound leaves were noticed. Significant variations in leaf length and leaf breadth among the accessions were recorded. The highest leaf length was recorded in TNAU Jn 1(10.22 cm) while higher leaf breadth was noticed in KAU Js 2 (05.35 cm). KAU Js 2 was superior in terms of leaf area (29.60 cm2 ). All the jasmine accessions were having opposite phyllotaxy. The dominant leaf tip type in jasmine accessions was the sharp leaf tip. Most of the accessions were devoid of leaf pubescence, only accessions belonging to Jasminum multiflorum and Jasminum auriculatum showed pubescence in leaves. Floral characters showed significant variations for all the parameters. While 80 % of the accessions recorded terminal and axillary flower bearing positions, the remaining twenty per cent of accessions had terminal flower bearing position. Most of the accessions showed cluster bearing habit and single whorled type flowers. Doublewhorled (KAU Js 2) and multi-whorled (KAU Js 4, KAU Js 8 and KAU Js 9) flower types were seen in 5% and 14 %, respectively. Pointed and round shaped flower buds were dominant in jasmine accessions. The majority of the accession exhibited white flower and flower bud colour. While, some accessions such as KAU Jm 3, KAU Jn 1, KAU Jn 2, TNAU Jn 1 and CO 2 Pitchi were having pink coloured flower buds. The highest flower bud length was observed in J. grandiflorum accessions, meanwhile, flower bud width was high in J. sambac accessions (KAU Js 1 and KAU Js 11). Significantly highest flower diameter was noted in the accessions TNAU Jn 1 and KAU Jn 1. The number of petals was high in J. sambac accession KAU Js 4, while low in J. grandiflorum accessions. A longer corolla tube length was noticed in Jasminum coarctatum (2.54 cm). Most of the accessions had fragrant flowers, except KAU Jm 2 and KAU Jm 3. With respect to the season of flowering, most of the accessions were found to be seasonal and some were observed to flower throughout the year (J. multiflorum and J. nitidum). The accession KAU Jm 1 was found superior in terms of total flower yield. Seed setting was noticed in J. auriculatum (KAU Ja 1), J. coarctatum (KAU Jc 1), J. nitidum (KAU Jn 2) and J. sambac (KAU Js 3). A close association between GCV and PCV were noted for most of the characters, indicating that the variations in these characters were due to the effect of genotype, and environment had little effect. High heritability and genetic advance indicated the additive gene effect and scope for selection and crop improvement. The residual effects for path analysis were 0.009 indicating, the selected eleven flower yield attributing characters all together contributed about 99 per cent of the variation in hundred flower weight per plant. Cluster diagram based on quantitative characters indicated that there exists much diversity among the accessions. The accessions were ranked for loose flower purpose, essential oil extraction and landscaping purpose. Based on the floral characters the accessions KAU Jm 3, KAU Jn 1, KAU Js 2, KAU Js 3, KAU Jm 2, TNAU Jn 1, KAU Js 9, KAU Js 1, KAU Js 11, KAU Jc 1 were found superior for loose flower purpose, while KAU Jn 1, TNAU Jn 1, KAU Jm 2, KAU Jm 3, KAU Js 2, KAU Jm 1, KAU Js 9, KAU Jg 1, KAU Js 8, CO 2 Pitchi were found superior for landscape purpose. For the extraction of jasmine concrete, the accessions KAU Ja 1 and all the accessions of Jasminum grandiflorum were found higher rank.