MSc

Water lilies are a group of fascinating aquatic perennial herb belonging to the genus Nymphaea. Among the different species of Nymphaea, Nymphaea nouchali is one common in south India. This species is commonly known as blue water lily, blue star water lily or star lotus. The plant is historically and functionally significant since it is associated with our culture and tradition. This species which forms an important constituent of aquatic flora possesses immense medicinal and ornamental values. Despite of its immense potentialities, water lily has received very little attention of crop improvement workers. Information on developmental pattern and reproductive biology which is fundamental for crop improvement programmes is lacking in this plant. Hence this investigation entitled ‘Reproductive biology of water lily (Nymphaea nouchali Burm.f.) was under taken up with the objective of elucidating the reproductive biology and developmental pattern of flowers and fruits in Nymphaea nouchali.
Two flower colour variants of Nymphaea nouchali- blue and white types maintained in cement tanks were selected for the study. The study was conducted during 2010-2012 in the Department of Plant Breeding and genetics, College of Horticulture, Vellanikkara.
The leaves of both the colour variants are simple, orbicular with sub-peltate lamina and deeply cleft near to the petiole base. The petiole of both the type was long, glabrous and brownish in colour with lamina floating on the water surface. The blue type was significantly superior to the white type for mean length of leaf as well as means width of leaf at middle and tip.
In both the types it took almost six days for the flower bud to reach the water surface and the flower opening occurred nearly three days after the bud reaching the water surface. Even after the flower opening the pedicel elongation continued in both the types to an extent of 4 cm. Maximum growth rate of the pedicel was observed on the day just prior to the flower opening. The white type produced longer flower bud and thus larger flowers when compared to blue type. However the circumference of the flower bud was more for blue type.
The flowers of both the types were faintly fragrant. The flowers opened in morning and closed in the evening hours and again opened on next day. The opening time of the flower varied from 7.30 am to 9.45 am. The closing time varied from 5.15 pm to 6.15 pm. Bright and sunny days favoured early opening of the flower. The blossom life was three days for blue type where as it was four days in white type. The flowers were produced throughout the year on an average of 3 to 4 days interval in both the types. Hence it can be well recommended for water gardens.
The flowers were found to be solitary, pedicellate, and complete with various floral whorls in spiral fashion on the floral axis. Significant variability was observed on various floral characters among the two types.
Each stamen consisted of a filament, anther and a sterile appendage at the tip. The initiation of dehiscence occurred by the longitudinal splitting of the anthers in both the types. The pollen dehiscence occurred only after complete opening of the flower. The stigma receptivity started 17 hours before flower opening and the receptivity was retained up to 20 hours after flower opening.
Honey bees, house flies and weevils were found to be the major insects visiting the flowers. Several dead insects were observed in the stigmatic cup of both the types indicated the insectivorous nature of the flower.
The pollen grains were found to be round, yellow in colour and monocolpate with reticulate exine in both the colour variants. No fruit or seed development were observed in both the colour variants. The absence of fruit or seed set can be attributed to very low fertility of the pollen and some incompatibility mechanisms in the flower. The vegetative propagation from leaf was found prominent in both the colour variants under study.