THE EFFECT OF DIFFERENT TREATMENTS ON THE GERMINATION OF LEWISIA HYBRID SEEDS.
Usually Lewisia is sold as an alpine or rock garden plant. Seedlings include a wide range of forms and colours and if other lewisias are nearby, new hybrids occur because many species cross easily. Introducing Lewisia as a new flowering potplant, needs therefore an intensive breeding program and a severe selection of the most commercial forms. To improve and speed up the germination two experiments were designed.
In a first experiment the influence of different cold treatments was investigated. A cold treatment (0–5°C) at moist conditions during 3 to 4 weeks gave the highest germination percentage (76 %). Part of the germination occurred during the stratification process itself. An alternating temperature of 5 to 15°C, applied after this process, slightly increased the germination (82 %). Only 16 % of the untreated seeds (at min. temp. of 14°C) were finally germinated.
In a second experiment, using growth regulators, a germination rate of about 55 % was obtained by first soaking the seeds in 10 % solution of NaOCl (10 % Cl) for 30 minutes and then soaked again in 100 mg/l GA3 or 0.6 ml/l Promalin during 24 hours. Controls showed a germination of 37 %. A higher concentration of GA3 or Promalin might increase the germination up to the percentage of the stratification treatment.