2019 ASHS Annual Conference

Two experiments were conducted in a greenhouse to evaluate the effects of specific ratios of narrow-band blue/red (447nm/627nm) Light Emitting Diodes (LEDs) on growth and yield of strawberry plants. In Experiment 1, ‘Albion’ plants were exposed to 7.0°C chilling for three weeks and then transplanted on 27 November 2017 into 3.8 L pots containing a 3:1 mixture of perlite and peat moss. Three single plant pots of each cultivar were placed on separate benches where light treatments would be randomly arranged. The plants were grown in an ebb and flood hydroponic system utilizing a modified Hoaglands nutrient solution. The plants were exposed to six LED light treatments with differing blue/red ratios (10B/90R; 20B/80R; 30B/70R; 40B/60R; 50B/50R; and 60B/40R), a full spectrum LED light, a high pressure sodium (HPS) light, or natural light only. The lights were adjusted to maintain 100 µmols·m²·sec¹ supplemental light from each treatment at the top of the canopy. Beginning on 7 February, the supplemental light treatments were established for 16 h/d (from 5 am to 9:00 pm). The ‘Albion’ plants were harvested from 15 March until 11 May. The plants were partitioned, and dry weights determined. All plants grown under supplemental LED or HPS lights had numerically greater total fruit yield and total plant dry weights than plants in natural light. Plants grown under full spectrum LED and HPS lights had fruit Soluble Solids Contents (SSC) of 10.3% and 10.0 %, respectively, on 7 May compared to 7.7% for fruit under natural light. A similar trial was established on 5 November 2018, but with six ‘Albion’ plants in each light treatment. Plants were grown in Milliard 15 cm wide hydroponic slotted pots filled with the same media and exposed to the same light treatments for 16 h/d. Fruit harvest began on 11 January 2019 and has continued until 12 April. Plants grown under full spectrum LED lights had significantly higher number and weight of fruit than plants in natural light. Plants grown under 50B/50R LED, 30B/70 LED lights, and HPS lights produced 85%, 74%, and 69%, respectively, higher yield than plants in natural light. Fruit from plants under HPS lights had significantly higher SSC/acid ratio than fruit in natural light in limited sampling thus far.