Horticultural Science and Technology 원예과학기술지 ISSN:1226-8763(Print) 2465-8588(Online)

The objective of the present study was to evaluate the effects of plant spacing (14-, 20-, and 31-cm) on the lateral branch length, shoot fresh and dry weights, yield, and glucosinolate content of watercress at 35 and 56 days after transplanting (DAT) in a hydroponic culture system. Two-week-old seedlings were transplanted into three deep flow technique systems in a greenhouse with three plant spacing treatments: 31-cm (36 plants per bed), 20-cm (72 plants per bed), and 14-cm (144 plants per bed). Each treatment had three beds and the size of each bed was 3.24 m². The lateral branch length, shoot fresh and dry weights, and yield were measured, and glucosinolate concentration in leaves and stems of watercress was analyzed at 35 and 56 DAT. Both lateral branch length and yield per unit area were significantly reduced by increasing plant spacing, whereas the shoot fresh and dry weights were significantly increased. The total concentration of glucosinolate in the shoots was higher at 56 DAT than at 35 DAT. Furthermore, at 35 DAT, the glucosinolate concentration was the highest in the leaves and stems of plants grown under 14-cm and 31-cm spacing, respectively, than under other spacing treatments. However, at 56 DAT, the total glucosinolate concentration was higher in the leaves and stems of plants grown under 20- and 31-cm spacing and under 14- and 20-cm spacing, respectively. The highest total glucosinolate content per shoot in a unit area was observed under 14-cm spacing at 35 DAT (6.58 mmol/shoot DW/m²) and under 20-cm spacing at 56 DAT (51.99 mmol/shoot DW/m²). These results suggest that watercress yield could be optimized by growing plants under 14-cm spacing and harvesting at 35 DAT, whereas growing plants under 20-cm spacing and harvesting at 56 DAT would be an optimal method for increasing glucosinolate content without negatively affecting the growth of plants grown under a hydroponic culture system in a greenhouse.