Experiment
Collection and identification of Pandanus species
From October 2007 to May 2009, a detailed survey was carried out along the Maharashtra, Goa, Karnataka and Kerala states of Southern India and male spadices and female fruits of seven Pandanus species (P. kaida, P. odorifer, P. canaranus, P. furcatus, P. palakkadensis, P. thwaitesii and P. foetidus) were collected. The geographical details (latitude, longitude and altitude) of each locality were recorded using global positioning system (Magellan GPS 315) (Supplementary Table S1, available online only at http://journals.cambridge.org). The collected species were assigned a collection number and morphological characters were recorded (Table 1). In addition, habitat and frequency of occurrence of each species were recorded. Based on the morphological characters, the collections were identified using regional, state and district floras and other literature (Stone, Reference Stone, Saldanha and Nicolson1976; Yoganarsimhan et al., Reference Yoganarsimhan, Subramanyam and Razi1981; Henry et al., Reference Henry, Chithra and Balakrishnan1989; Bhat, Reference Bhat1992; Sharma et al., Reference Sharma, Karthikeyan and Singh1996). Authentication of each collected species was done at Botanical Survey of India (BSI), Western Circle, Pune, and type specimens were deposited therein. In addition, information regarding the traditional uses of Pandanus species was collected from local people, farmers and tribal people (Supplementary Table S3, available online only at http://journals.cambridge.org).
Table 1 Staminate inflorescence characteristics of Pandanus species from Southern India
+++, high; ++, moderate; +, low; values are means of five replicates.
Characterization and sensory evaluation of male spadices of Pandanus species
Mature male spadices (five to ten) of each species were characterized with respect to bract number and fresh weight per inflorescence, and bract length and colour. Sensory evaluation for intensity of fragrance was performed by placing cut pieces of bloomed male spadices of Pandanus spp. in glass vials and sniffing the fragrance against the male spadix of P. odorifer as the standard. The intensity of fragrance was scored based on a three-point scale as high, moderate and low.
Discussion
All Pandanus species were found endemic to their localities and distributed along the coastal (P. odorifer) and intercoastal regions (P. furcatus, P. canaranus and P. palakkadensis) (Fig. 1). P. thwaitesii and P. foetidus were found located in the forest areas under the tree canopy. P. odorifer, P. canaranus and P. thwaitesii were recorded in all four states, whereas P. kaida and P. foetidus were recorded in all states except Maharashtra. P. palakkadensis had been found to occur only at a few places in the Palakkad district of Kerala state (Nadaf et al., Reference Nadaf, Zanan and Wakte2011). P. canaranus and P. furcatus had the largest distribution of the species collected and P. palakkadensis the smallest (Fig. 1).
Fig. 1 Distribution and area size of Pandanus species in Southern India. (A colour version of this figure can be found online at http://www.journals.cambridge.org/pgr)
Table 1 depicts the analysis of staminate inflorescences of Pandanus species. The average number of bracts varied from 7.4 (P. canaranus) to 11.6 (P. odorifer). The range of bract length was from 10–30 cm (P. thwaitesii) to 20–70 cm (P. kaida). The fresh weight of bracts varied from 283.2 g (P. thwaitesii) to 476.0 g (P. kaida). P. kaida recorded maximum number of bracts with maximum bract length and fresh weight. P. thwaitesii and P. kaida recorded the highest fragrance score compared with P. odorifer. An interesting positive correlation between flower colour and fragrance was observed such that the intensity of fragrance found increased with increase in yellow colour intensity of bracts. All the staminate inflorescences showed ephemeral nature with average life of 8–12 d after blooming (Supplementary Fig. S1, available online only at http://journals.cambridge.org). The flowering time of most of the species was from July to October (rainy season), except P. thwaitesii and P. foetidus that blossom from November to February (winter season) (Supplementary Table S2, available online only at http://journals.cambridge.org).
P. odorifer, which supports the local perfume industry by the perfume extracted from the male inflorescence, is cultivated in the Ganjam district of Orissa, India (Panda et al., Reference Panda, Panigrahy, Das and Panda2007, Reference Panda, Das and Panda2009). It is estimated that about 35 million flowers (~3500 tons) are processed annually to produce fragrance and flavour materials worth Rs. 400 million (US$ 8.9 million) (Anonymous, 1996). The peculiar sweet fragrant smell of P. odorifer flowers represents 85 volatile oil compounds, mainly due to the major constituents 2-phenyl ethyl methyl ether (37.7%), terpinen-4-ol (18.6%), α-terpineol (8.3%) and 2-phenyl ethyl alcohol (7.5%) (Raina et al., Reference Raina, Kumar, Srivastava, Syamsunder and Kahol2004). The study reveals the fragrance potential of P. thwaitesii, P. kaida and P. palakkadensis, which could be exploited commercially for extraction of essential oil.
Acknowledgements
The authors thank Western circle, BSI, Pune for authenticating the plant specimens and acknowledge the financial assistance of the BCUD, University of Pune, Pune, India to carry out the survey.
