This study has been performed to investigate the efficiency of the chemical mutagen ethyl methanesulphonate (EMS) to induce mutations in Saintpaulia. In vitro leaf sections of Saintpaulia cv. Crystobal were exposed to various EMS treatments at 0%, 0.2%, 0.4%, and 0.6% for 30, 60, 120, and 240 min after which adventitious shoots were recovered from the treated explants. Shoots producing at least six leaves were induced to root and the resulting plantlets were transplanted to soil. A total of 1838 plantlets was grown to flowering stage and 10 mutants were identified. Four of the mutants were variegated leaf chimeras and the remaining six presented variations at the level of flower color and/or fringe. Results in the present study showed the efficiency of EMS to induce in vitro mutation of Saintpaulia and the method can be used in the future to assist breeding in this popular ornamental plant.
Jong-Yi Fang and Siguina Traore
Boris Andrés Bran Barrientos and Jong-Yi Fang
Spathoglottis plicata is an attractive, easy-to-grow, and floriferous terrestrial orchid that has become the most important horticulturally cultivated Spathoglottis species in Southeast Asia. The present research was conducted to study the asymbiotic seed germination and seedling development of this orchid under the influence of various photoperiod and medium treatments. Seeds from 28-day-old capsule were sown on five culture media, including half-strength Murashige and Skoog medium (1/2 MS), Orchid Seed Sowing Medium (OSSM), BM-1 Terrestrial Orchid Medium (BM-1), Vacin and Went Modified Orchid Medium (VW), and Knudson C Orchid Medium (KC), and incubated under 0/24-hour or 16/8-hour light/dark photoperiod. Seed germination occurred in all photoperiods and media tested but at different paces. Seeds subjected to total darkness germinated more rapidly in the first 3 weeks than those subjected to light. However, seed germination under light overtook or even exceeded seed germination under dark starting on the fourth week of culture. Seedlings grown on the OSSM and VW media showed the fastest development as they reached the advanced stage (Stage 6) within 11 weeks of culture. Seedlings on the BM-1 medium were the slowest to evolve, as they required more than 16 weeks’ time to complete all the developmental stages. Light-incubated advanced stage seedlings were subcultured on the same medium until leaves and roots were well developed and acclimatized in the greenhouse with 100% survival.