2017 ASHS Annual Conference

Strawberries (Fragaria × ananassa) are a rich source of nutrients, phytochemicals, and fiber. Strawberries have been grown in greenhouses in many parts of the world. In Europe, they have been successfully grown since early 1970's but they have not been grown much in Canada. There is an increasing interest recently in Canada to the production of strawberries in greenhouses. Strawberry plants are very sensitive to light environments. The objective of this study was to examine the effects of different doses of far-red LED light on vegetative growth and fruit yield of strawberry grown during winter season in a greenhouse. In this study, we examined four levels of far-red LED light ( 0 (control), 8, 16 and 24 mmol m^-2 s^-1). Strawberry (cv. Albion) plug transplants were obtained from Carther Plants (Thamesville, ON, Canada) and kept for 4 weeks in a greenhouse (23°C day/19°C night temperatures, 10-h photoperiod) prior to planting in an experimental greenhouse. Strawberry plug transplants were planted onto rockwool (50 × 20 × 7 cm³) slabs for hydroponic culture in the experimental greenhouse at a plant density of 60 plants m^-2. The plants were drip-irrigated using complete nutrient solutions based on standardized recommendations. The initial EC and pH was set at 2.2 mS cm^-1 and 5.5, respectively. The greenhouse day/night heating temperatures were set at 17/15°C while ventilation temperature was set at 21°C. Greenhouse humidity was maintained between 65 and 85%. The top high pressure sodium lamps provided 110µmol m^-2 s^-1 of supplemental lighting to all the plants from 07:30 to 17:30 when outside global solar radiation was below 500 Wm^-2. Vegetative growth, fruit and flower numbers were counted at three weeks intervals. All 3 levels of far-red LED light increased plant growth, and the number of flower and fruit over the control. Strawberry plants cultured under 16 µmol m^-2 s^-1 of far-red LED light had the highest fruity yield. This information will be useful for growers to choose proper dose of far-red LED light to improve strawberry production in greenhouses.