Carpology seed storage and germination of South Indian rauvolfia species
Rauvolfia is a medicinally important genus of shrubs or small trees belonging to the family Apocynaceae comprising 80 species. Among many shrubs with their distribution in tropical Asia, Africa and America, the selected south Indian species are R. hookeri Srinivas. et Chithra, R. micrantha Hook. f., R. serpentina (L.) Benth. ex Kurz., R. tetraphylla L. and R. verticillata (Lour.) Baill.
Quantitative and qualitative characters of fruits/seeds, simple and scanning electron microscopic (SEM) macro and micro morphological seed characters, physiological behavior of seeds linked with moisture content, germination, etc. were analyzed. Seed samples were categorized on the basis of their response to different moisture levels before being tested for germination. Dormancy-breaking experiments were conducted by using the methods like mechanical scarification, pretreatments with GA3, conc. H2SO4, hot water and distilled water. Short-term (one week) storage at different temperatures and long term storage with apt storage conditions were also experimented. Seedling morphology up to 5th leaf stage was also documented.
From this study, morpho-physiological changes through which the fruits and seeds pass during their development until ripening were revealed. Through SEM studies, the micro morphological features for species segregation were documented and a key was proposed for the purpose. Dormancy type of the five species was categorized and methods for breaking dormancy were proposed. Seed storage behavior revealed R. hookeri as intermediate while others as orthodox. Out of the seed and seedling morphology, separate keys were proposed for augmenting species identification.