Red, White, and Yellow Tubes Enhance PAR Reflectance and Seedling Quality of Corymbia citriodora (Hook.) K.D.Hill & L.A.S.Johnson in Combination with a Bioinoculant Based on Chlorella vulgaris Beijerinck

Eucalypt cultivation (Eucalyptus and Corymbia spp.) in Brazil is extensive, primarily due to its rapid growth, adaptability, high yield potential, and suitability for different production chains. Consequently, attention must be given to the quality and health of its propagation materials since high-quality seedlings show greater field survival and growth performance. Therefore, the present study aimed to evaluate the performance of Corymbia citriodora (Hook.) K.D.Hill & L.A.S.Johnson, seedlings cultivated in tube trays of different colors, in order to assess how colour-driven differences in light reflectance affect seedling growth and physiology, and treated with a microalga-based bioinoculant (Chlorella vulgaris Beijerinck). The experiment was conducted at the Mato Grosso do Sul State University, Cassilândia Campus. The trial followed a completely randomized design in a 5 × 2 factorial scheme (four tray/tube colors plus control × bioinoculant application plus control), with four independent trays (replications) per combination. The bright colors used were white, red, blue, and yellow in 96-cell trays. Applications were performed at 60 and 90 days after sowing (DAS). At 97 DAS, the number of leaves, seedling height and shoot diameter, along with shoot, root, and total dry masses, were evaluated. Data were analyzed using the Sisvar software, and seedling quality was assessed by the Dickson Quality Index. The use of colored trays and tubes represents a promising technique for producing C. citriodora seedlings, particularly those with higher light reflectance. Cultivation in white or red trays and applying a Chlorella vulgaris-based bioinoculant promotes high-quality C. citriodora seedlings. Using trays with white, yellow, and red tubes enhances the physiological potential of C. citriodora seedlings. The bioinoculant significantly increased chlorophyll b content in seedlings grown in blue, red, and control trays.