Anjali Kak

Seed trichomes and spermoderm pattern in few wild Hibiscus species-A tool for species identification

Seed morphological characteristics are useful taxonomic features, helpful in identification of large number of species and genera. Seed characters, such as shape, size and seed-coat surface, have low phenotypic plasticity and are less affected by environmental conditions. The purpose of this study was to describe and compare external seed morphological characteristics and trichomes of seven hibiscus species using light and scanning election microscopy to evaluate their possible use for taxonomic considerations. Seeds showed three major types of spermoderm patterns and considerable variation in the seed trichome shape and number of hairs per trichome. Using seed trichome along with spermoderm patterns, a tentative key for species identification was prepared.

Para taxonomic characters and seed germination behaviour in three varieties of Coix lacryma jobi L.

Jobs tear, a potential energy source, is widely used as folk medicine for the treatment of tumours and gastrointestinal problems. The present investigations on wild and cultivated species of Coix received at National Genebank for long term conservation were done to develop dormancy breaking protocols. Based on qualitative seed morphological characters, the species status of one accession was validated as wild Coix, Coix lacryma jobi var. stenocarpa. Of the eight different scarification treatments, 100% acid treatment for 120 min. was recorded maximum germination in two wild species Coix lacryma jobi var. lacryma jobi and Coix lacryma jobi var. stenocarpa while 50% acid treatment for 30 min. gave maximum germination in cultivated species, Coix lacryma jobi var. mayuen. After breaking dormancy, seedling were well established in fields. Thus, for better utilization of this species removal of seed dormancy is essential and this dormancy breaking protocol will be of great use in future for utilization of Coix species.

Responses to Seed Dormancy Breaking Treatments in Wild Hibiscus species

To determine the most suitable means of overcoming seed dormancy in seven wild spe-cies of Hibiscus (Hibiscus acetosellaWelw. ex Fic., Hibiscus calyphyllus Cav., Hibiscus surattensis L., Hibiscus lobata Kuntze, Hibiscus radiatus Cav, Hibiscus vitifolius L., Hibiscus panduriformis Burm. f) and their accessions, seeds were exposed to various pre-treatments such as scarification with hot water and sulphuric acid for varying du-rations. Treated seeds were evaluated for their viability to assess the impact of given treatments. The results revealed that concentrated sulphuric acid scarification treatment for 10 min was highly effective in breaking hard-seed dormancy in all accessions of H. calyphyllus.Concentrated sul-phuric acid treatment for 10–20 min in H. vitifoli-us; 25 min in H. surattensis; 30 min in H. radiatus; 5min in H. lobatus was effective in overcoming hardseededness. Hot water treatment at 80°C for 10 min was effective in H. acetosella and H. pan-duriformis. However in H. panduriformis concen-trated acid treatment for 5min was equally effec-tive as hot water treatment. This study therefore clearly demonstrates the efficacy of concentrated sulphuric acid pre-treatment for 10–30 min and hot water treatment at 80°C for 10 min as an ef-fective enhancer of seed germination of wild spe-cies of Hibiscus. Because of the variation in the seed size and degree of hardseededness among the species no single treatment can be recom-mended for breaking dormancy in all species.