Collection and evaluation of marigold (Tagetes spp.) genotypes for humid tropics

Abstract

The present study entitled ‘Collection and evaluation of marigold (Tagetes spp.) genotypes for humid tropics was conducted in the Department of Pomology and Floriculture, College of Agriculture, Vellayani during 2012-2015, with an objective to collect and evaluate the genotypes of Tagetes spp. for growth, yield of fresh flowers and floral attributes in two planting seasons, ie, October and May planting and to select promising genotypes for loose flower production and for landscaping. The experimental material consisted of twenty five genotypes of Tagetes erecta and five genoytpes of Tagetes patula. These were evaluated in the field in a randomized block design with three replications. Significant differences were observed among the genotypes for plant growth characters, foliage characters, flowering and yield characters and flower characters in both planting seasons. In both October and May plantings, TEG 5 and TEG 6 maintained greater plant height and the lowest plant height were found to be in TPG 17 and TPG 18. The maximum plant spread was recorded in TEG 5 in October planting and in TPG 21 in May planting. The highest number of primary branches per plant was recorded in TEG 6 followed by TEG 5 in October planting and in TEG 16 followed by TEG 5 and TEG 8 in May planting. The highest number of secondary branches was recorded by TEG 14 in October planting and by TPG 21 in May planting. Among flowering and yield characters, in October planting, the lowest number of days to flowering was recorded in Tagetes patula genotypes, TPG 19, TPG 18 and TPG 21 (33.33 days) and the lowest number of days to flower opening in TPG 21 and TPG 17 (45.33 days). In May planting, the Tagetes erecta genotype TEG 11 recorded the lowest number of days to flower initiation (49.00) and flower opening (68.33). TEG 29 recorded the longest flowering duration in both October and May planting. The maximum number of flowers per plant and flower yield per plant was observed in TEG 16 in October planting. In May planting, TPG 18 followed by TEG 16 recorded the maximum number of flowers. The genotype TEG 16 also recorded the highest flower yield per plant in May planting and the highest number of viable seeds per plant in both the seasons. TEG 11 recorded higher values for fresh weight of flower in both the seasons of investigation. In October planting and May planting, the highest value for petal meal per kg of fresh flowers was recorded in TEG 29 and the maximum petal meal per ha was recorded in TEG 5 in October planting and in TEG 29 in May planting. The highest total carotenoid content was recorded by TEG 3 followed by TEG 2 in both the seasons. Among the flower characters, TEG 5 the highest number of ligulate floret whorls and TEG 11 recorded the highest value for length of floret, flower diameter, girth of floral receptacle in both the seasons. Significantly higher flower stalk length was observed for TEG 3 and the longest vase life was recorded by TEG 7 in both the seasons of investigation. Genetic variability studies showed that genotypic coefficient of variation (GCV) was higher than phenotypic coefficient of variation (PCV) for all the characters. High GCV and PCV and high heritability was observed for all the characters studied. Correlation studies revealed a highly significant positive correlation of flower yield with number of flowers per plant, plant spread, fresh weight of flowers, length of floret, crop duration and number of secondary branches per plant. Path analysis studies showed that fresh weight of flowers had the highest direct positive effect on flower yield per plant followed by number of flowers per plant and plant height. Cluster analysis based on D2 values divided the thirty genotypes of marigold into six clusters with Cluster V recording the maximum number of genotypes and Cluster I, the minimum number of genotypes.Seasonal evaluation of the genotypes showed that May planting was found to be better than October planting in terms of plant growth characters, flower yield and flower characteristics. Earlier initiation of flowering was however observed in October planting in all the genotypes. The present study revealed that, the Tagetes erecta genotypes TEG 5, TEG 29, TEG 25, TEG 30, TEG 22, TEG 11 and TEG 7 may be suitable for commercial loose flower production. The genotype TEG 16 with semiupright habit may be suited for plant compactness and flower production. The genotypes TEG 3 and TEG 2, with higher carotenoid content may be suitable for pigment extraction. The Tagetes patula genotypes, TPG 21 and TPG 18 with dwarf spreading plant habit and the Tagetes erecta genotype TEG 11 with semiupright plant habit may be suitable as flowering ground covers in landscaping. The wide range of genetic variability available in marigold genotypes can be utilized for further crop improvement programmes through direct selection and hybridization.