Growth and total nutrimental absorption of baby romaine lettuce cultivated with led lighting under plant factory system

Abstract

In this research, the influence of the quality and intensity of light on the growth and total absorption of nutrients in the baby romaine lettuce crop was evaluated. The growth variables evaluated were: fresh and dry weight of root and leaves, number of leaves and total nutrient absorption (N, P, K, Ca, Mg, Cu and Zn). The results showed significant differences between treatments (p ≤ 0.05), highlighting a greater growth of the crop under the treatment of red + blue + white light supplement, both in dry and fresh weight, number of leaves and total absorption of nutrients, demonstrating that a higher intensity of light considering its quality (irradiated electromagnetic spectra) promotes greater growth in the crop. The energy efficiency in the production of dry weight with respect to the accumulated light intensity was diminished in treatment 3 because the white light supplement provided other electromagnetic spectra that are not as efficient in photosynthetic processes compared to red and blue (treatment 1 and treatment 2); requiring an accumulated light intensity equal to 1.87 mol·m–3 to produce 1.0 g of dry weight, higher value than treatment 1 (1.57 mol·m–3) and treatment 2 (1.53 mol·m–3).