Light Quality Produced by LED Combinations on the Growth of Cucumber Seedlings (Cucumis sativus L.)

Objective: To determine the influence of light quality on the growth of cucumber plants (Cucumis sativus L.), through the intensity of expression of different characteristics. Design/methodology/approach: A completely randomized block design was used with four treatments and 10 repetitions. The treatments consisted of combinations of white (B), red (R) and blue (A) LEDs placed in growth chambers, with percentages of: 100B-0R-0A, 70B-30R-0A, 80B-0R- 20A and 60B-27R-13A, growth chambers with LED-based lighting systems lamps were used. Seeds of the 'Top 1056’ cultivar, Persian type, were sown. The response variables evaluated in the cucumber plants were plant height, stem diameter, leaf greenness, leaf area, fresh and dry biomass of leaves, stem and root of the plants. Results: The light spectrum emitted by the LEDs influenced the morphology of the cucumber seedlings. With the 80B-0R-20A treatment, where there was greater blue light emission, greater leaf greenness and stem diameter were achieved. In contrast, the 70B-30R-0A treatment, with more red light, increased plant height and leaf area. Fresh and dry biomass of leaves and stem were also modified by light quality. Plants grown in the 70B-30R-0A treatment produced the greatest amounts of fresh and dry biomass, both stem and leaves. Limitations on study/implications: The use of artificial lighting systems, with different spectral compositions for production in controlled environments presents a viable opportunity to enhance crop growth. Therefore, it is important to investigate how the light spectrum of different LED combinations affects the growth of cucumber seedlings. Findings/conclusions: The light spectrum emitted by LED combinations influenced the morphology of cucumber seedlings, since with 80B-0R-20A treatment, resulted in greater leaf greenness and stem diameter, while the 70B-30R-0A treatment increased the height and leaf area of ​​the plants.