Performance evaluation and hybridization in waterlily (Nymphaea spp)

Abstract

The research programme entitled “Performance evaluation and hybridization in Waterlily (Nymphaea spp.)” was conducted at the Department of Floriculture and Landscaping, College of Agriculture, Vellayani, Thiruvananthapuram, during 2024- 2025 to evaluate the performance of selected waterlily hybrids for growth, flowering, and floral characteristics, and to facilitate crop improvement through hybridization for the development of novel phenotypes. In the first experiment, fifteen F₁ hybrids obtained from a previous study were evaluated for their vegetative and floral traits. The hybrids exhibited significant morphological diversity. Among the quantitative vegetative characters, the highest leaf length and breadth were recorded in T10. For floral attributes, T4 (7.97 ± 0.17 cm) had the highest flower diameter, followed by T13 (7.88 ± 0.22 cm), and T5 (6.55 ± 0.29 cm) had the lowest. Sepal and petal dimensions also varied widely, indicating substantial variability in floral architecture. Qualitative traits showed distinct variation in leaf shape, margin, venation, as well as in floral form and pigmentation. Pedicel colour ranged from yellowish-green to olive-brown, petals exhibited acute to rounded tips, and flower colours varied from light blue and bluish white to pale pink and yellowish green. Among vegetative traits, the highest phenotypic and genotypic coefficients of variation (5.10% and 4.28%) were observed for leaf width, while the lowest were for leaf longevity. In floral traits, petal width showed the most significant variation (PCV 23.28%; GCV 15.98%), whereas the length of the flower bud exhibited the least. The slightly higher phenotypic variance over genotypic values indicated a moderate environmental influence on trait expression. Principal Component Analysis (PCA) effectively differentiated the hybrids based on overall vegetative and floral performance. Three hybrids-T4, T10, and T13- consistently ranked among the top performers across traits, forming a distinct cluster in the index plot. Based on their superior vegetative vigour, floral quality, high pollen fertility, and extended stigma receptivity, these three hybrids were selected as parents for the hybridization programme undertaken in the present study to develop novel waterlily phenotypes. In Experiment II, hybridization was performed among three selected F₁ hybrids (T4, T10, and T13) and three parental varieties with desirable phenotypes, namely Ratsamee Chan, Foi Thong, and Chanwad, in all possible combinations. All crosses exhibited good compatibility, with fruits maturing within 19-34 days after pollination. The average number of seeds per fruit ranged from 300 to 540, while germination percentage varied between 31% and 74%, occurring within 6-10 days after sowing. The crosses Ratsamee Chan × T4 (73.94%) and T10 × Ratsamee Chan (72.36%) recorded the highest germination percentages. The hybrid seedlings flowered within 60-90 days of sowing. Flowering was observed in five cross combinations: T10 × Ratsamee Chan, Foi Thong × Ratsamee Chan, Ratsamee Chan × T4, T10 × T13, and Foi Thong × Chanwad. Crosses involving Ratsamee Chan and Foi Thong as parents produced the most vigorous and morphologically superior progenies. Among the newly developed hybrids, T10 × RC-8, FT × RC-1, FT × RC-2, FT × RC-5, FT × RC-9, and FT × C-1 exhibited distinct variations in vegetative and floral traits compared to their parents and were identified as promising. Overall, the results demonstrate the effectiveness of inter- varietal and inter-hybrid crosses in generating phenotypically diverse and promising Nymphaea hybrids, highlighting their potential for genetic improvement and enhancement of ornamental value.