Post-sown priming with a potting mixture to improve emergence of Malabar spinach, Basella alba L.

Individual seeds of Malabar spinach or Malabar nightshade Basella alba L. were sown in plastic cells of flats with a commercial potting mixture (''Shinkenbyokun, type 140'') with three different water contents. The moisture levels were adjusted by adding 16, 52, and 100g of water to 500g potting mixture. After sowing, the plastic flats were stored for different periods at 15 and 25 degrees C and then watered, and transferred to growth chambers controlled at 30 degrees C (day) and 20 degrees C (night), and an 8-hr photoperiod to induce emergence. Seeds, in flats with 52g water and stored at 15 degrees C for 10 days, began to emerge 2 days after transfer to the growth chambers and attained 63 to 70% emergence within 5 days. Seeds without the post-sown treatment (control) emerged 5 to 6 days after transfer; the number of seeds emerging gradually increased and reached 23 to 24% 20 days after transfer. A high percentage of seeds emerged in the post-sown treatment of 52g water at 25 degrees C for 5 days. Results of the two treatments showed that the rate of emergence was faster and the length of the hypocotyl was less variable in the post-sown treatment of 52g water kept at 15 degrees C for 10 days. Therefore, the optimal treatment of improving the emergence of Malabar spinach seeds is to sow them in a potting mixture with a moisture content equivalent to 52g water per 500g mixture (water content of 41 to 45%) and chill them at 15 degrees C for 10 days.