Effects of planting distances on the growth and yield of Lactuca indica L. 'Seonhyang'

Lactuca indica L., a perennial belonging to Compasitae, grows in the wild in Korea. It is used as vegetable for wrapped rice or meat, cooked greens, kimchi and pickle. In Korean medicine, it is used for strengthening the stomach, sedation, urination, sweating amongst other uses. It has a bright future as a health food. Therefore, we researched the effect of different planting distances of Lactuca indica L. 'Seonhyang' on its growth and yield. Seeds were sown in 105 cells tray-pot on March 4, 2013 in greenhouse and raised for 45 days. Seedlings were planted at 9 planting densities (10x10, 10x15, 20x15, 20x20, 20x25, 30x25, 30x30 and 30x40 cm) on May 2 in the field, which had been prepared with 2 t of compost and N:P:K=14:10:9 kg 1000 m(-2). We harvested stems when leaves were about 1 cm in diameter and 25 cm in length. The first harvest was June 20, the second was July 20 and the third was August 19. The growth and yield plant(-1) were greatest in the first harvest at a planting density of 30x25 cm (leaf length 27.8 cm, leaf width 8.6 cm, stem width 14.8 mm, chlorophyll 47.4 SPAD, yield 236.1 g plant(-1)) and total yield was estimated to be 3,833 kg 10 a(-1). At a spacing of 10x10 cm, leaf length was 26.7 cm, leaf width was 6.6 cm, stem width was 9.3 mm, chlorophyll was 34.7 SPAD and yield was the lowest per plant at 66.6 g. However, the total yield of 7,910 kg 1000 m(-2) was twice that for a spacing of 30x25 cm. Plants grown at a spacing of 10x10 cm were very suitable for making pickle and kimchi because the stems were slim. The yields decreased according to harvesting time (4,662 kg 1000 m(-2) in the 1st, 2,520 kg 1000 m(-2) in the 2nd and, 728 kg 1000 m(-2) in the 3rd harvest).