Performance evaluation of cosmos (Cosmos spp.) genotypes for flowering and flower quality traits in the hill zone of Karnataka

Introduction

Cosmos (Cosmos spp.) is a popular ornamental flowering plant belonging to the family Asteraceae. The name Cosmos is derived from the Greek word Kosmos, meaning beauty or ornament. Native to Mexico and Central America (Moshawih et al., 2017) [11] . Cosmos is widely grown for landscaping, bedding and cut-flower purposes because of its attractive flowers, long flowering period and ease of cultivation. The two most important species are Cosmos bipinnatus, which bears pink, white, red and violet flowers and Cosmos sulphureus, which produces yellow, orange and scarlet flowers. Cosmos grows well under warm and sunny conditions and adapts to a wide range of soils, performing best in neutral to slightly alkaline soils. It is a hardy, low-maintenance crop suitable for gardens and landscapes. This is an important ornamental flowering crop valued for its attractive blooms, extended flowering period, adaptability to diverse environmental conditions and low maintenance requirements (Paniagua et al., 2015) [14] . The availability of diverse genotypes offers opportunities for selecting superior types with desirable growth, flowering and seed yield traits. Several studies revealing the performance of different varieties of different crop at specific agro-climatic regions viz., in China aster the variety Phule Ganesh White recorded early flower bud initiation (52.05 days), minimum days to 50 per cent flowering (61.63 days), largest flower diameter (7.00 cm), highest number of flowers per plant (48.70). Arka Poornima exhibited the longest vase life (6.00 days), whereas Phule Ganesh White recorded the highest shelf life of loose flowers (3.20 days) (Swathi et al., 2023) [20] . In Chrysanthemum, Kolar Local exhibited early flowering, recording the minimum days to first flower appearance (90.59 days) and 50 per cent flowering (99.66 days), along with the longest flowering duration (149.33 days) and crop duration (239.55 days) (Roopa et al., 2018) [17] .

Materials and Methods

The investigation was carried out using 16 Cosmos genotypes viz., Ladybird Scarlet, Ladybird Orange, Ladybird Yellow, Cosmic Yellow, Limara Lemon, Bright Light, Sagara Collection-1, Bagalkot Collection, Sensation, Sonata Pink, Casanova, Sagara Collection-2, Sonata White, Sonata Red Shade, Mandarin and Opus Dwarf (Plate 1), with three replications in a Randomized Complete Block Design (RCBD), carried out under an open-field conditions at the Experimental Block, School of Post Graduation Studies, Iruvakki under Keladi Shivappa Nayaka University of Agricultural and Horticultural Sciences, Shivamogga during 2025-26. Standard cultural practices were followed throughout the crop period. The objective of this investigation was to assess the performance of cosmos genotypes for flowering and flower quality traits under the hill zone of Karnataka. The seedlings were transplanted onto raised beds with a spacing of 30×30 cm. Observations were recorded in each genotype for days taken for flower bud initiation, days taken for flower opening, days taken for 50% flower opening, number of flowers per plant, flower diameter (mm), Average flower weight (g), Number of petals per flower, Number of whorls per flower, disc diameter (mm), disc length (mm), petal length (cm), petal width (cm), shelf life (hours), vase life (days).

Plate 1: Pictorial Representation of Cosmos Genotypes evaluated in the study

Results and Discussion

The findings of the present investigation were interpreted and are presented in Tables 1 and2 based on the observations recorded during the study.

A. Mean performance of genotypes for flowering traits

The analysis of variance revealed significant differences among the sixteen Cosmos genotypes for all flowering parameters, indicating the existence of substantial genetic variability. The mean performance of the genotypes for flowering traits is presented in Table 1.

The genotype Sensation recorded the minimum days taken for flower bud initiation (33.13 days), followed by Sonata Pink (38.80 days) and Limara Lemon (42.80 days), whereas Mandarin (59.13 days) and Bright Light (58.00 days) required the maximum number of days for flower bud initiation. This variation might be mainly governed by genetic makeup of the genotypes. Similar variation in flowering behaviour has been reported by Dharmendra et al. (2019) [2] and Kolur et al. (2022) [9] in China aster, Patil et al. (2022) and Sharma and Topno (2024) [18] in Chrysanthemum, Kharjana and Fatmi (2022) [8] in Zinnia and Jyothilaxmi (2019) [7] in Gaillardia. The genotype Sensation also recorded the earliest flower opening (37.27 days), followed by [2] in China aster, Patil et al. (2022) in Chrysanthemum and Girange et al. (2017) [3] in Gaillardia. The minimum number of days to 50 per cent flowering was recorded in Sensation (45.33 days), followed by Sonata Pink (50.27 days) and Bagalkot Collection (50.80 days), whereas Bright Light (75.27 days) recorded the maximum days to 50 per cent flowering, followed by Sagara Collection-1 (72.07 days) and Mandarin (69.67 days). The observed variation could be due to inherent genetic differences among the genotypes and their differential response to environmental conditions. Similar results were reported by Swathi et al. (2023) [20] in China aster, Patil et al. (2022) in Chrysanthemum, Saniya et al. (2021) [19] in Gaillardia and Naik et al. (2019) [13] in Marigold. [5] in Chrysanthemum, Patel et al.

B. Mean performance of genotypes for flower quality traits

(2023) [15] in Gaillardia and Thakur and Kaur (2023) [21] in Marigold.

The maximum flower diameter was observed in Sensation (77.71 mm), followed by Bright Light (69.84 mm) and Opus Dwarf (61.44 mm), whereas Sonata White (29.93 mm) recorded the minimum flower diameter. Larger flower size is mainly a varietal characteristic and depends upon petal size and expansion. Similar observations were reported by Kolur et al. (2022) [9] in China aster, Patil et al. (2022) in chrysanthemum, Hegde et al. (2022) [4] in dahlia and Kharjana and Fatmi (2022) [8] [4] in dahlia, Arulmani et. al. ( 2015) [1] in Gaillardia and Manukumar et al. (2025) [10] in Marigold. [17] in Chrysanthemum, Rashmi et al. (2016) [16] in Gladiolus, Hegde et al. (2022) [4] in Dahlia and Jaseena et al. (2024) [6] in China aster. The maximum shelf life was observed in Sagara Collection-1 (65.60 hours) followed by Mandarin (60.80 hours) and Bright Light (59.20 h), whereas Opus Dwarf (27.20 hours) exhibited the minimum shelf life. Similarly, Opus Dwarf (6.20 days) recorded the longest vase life, followed by Mandarin (5.67 days) and Sagara Collection-1 (5.47 days). Longer shelf and vase life may be due to slower senescence, greater carbohydrate reserves and better moisture retention. Similar observations have been reported by Roopa et al. (2018a) [17] in Chrysanthemum, Kolur et al. (2022) [9] in China aster and Hegde et al. (2022) [4] in Dahlia.

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