METHODS TO PROMOTE FRUIT FORMATION AND ASYMBIOTIC SEED GERMINATION OF CALANTHE TSOONGIANA T. TANG ET F. T. WANG

摘要

Calanthe tsoongiana T. Tang et F. T. Wang, a terrestrial orchid that is endemic to China, has become rare and endangered due to limited natural reproduction and habitat destruction. There is an urgent need to conserve this species, while it has been poorly studied. Methods to promote fruit formation and asymbiotic seed germination of C. tsoongiana were used. The fruit set of C. tsoongiana was only 2.5% in the natural habitats. Artificial pollination resulted in 100% of capsule formation and all capsules survived to full maturity by bagging treatment. The seeds collected at 150 days after pollination were the optimum for asymbiotic germination. Among the six researched basal media the earliest initiation of germination and the highest germination were observed on VW (50.5 days, 32.3%) and half-strength MS (50.2 days, 32.9%). No significant effect existed among three temperatures (15 +/- 2 degrees C, 20 +/- 2 degrees C, and 25 +/- 2 degrees C), while a 16 h photoperiod of 20 mu mol m(-2) s(-1) was better than a 16 h photoperiod of 56 mu mol m(-2) s(-1) or continuous darkness for seed germination and seedling formation of C. tsoongiana. In conclusion, the best germination (32.3-32.9%) was obtained in 150 DAP seeds that cultured on VW and half-strength MS medium under a 16 h photoperiod of 20 mu mol m(-2) s(-1) at 15 +/- 2 degrees C to 25 +/- 2 degrees C. Pretreatment with 1% sodium hypochlorite (NaOCl) for 40-60 min was effective in advancing the initial of germination and improving the germination.