Crescimento de mudas de Eucalyptus camaldulensis em substratos à base de casca de arroz carbonizada

Abstract

Based on the importance of substrates in the production of forest seedlings, this work aimed to evaluate the technical feasibility of 13 substrates in the production of Eucalyptus camaldulensis seedlings, also assessing the correlation between their physical and chemical properties with seedling growth. The substrates were prepared as a mixture of commercial substrate based on semi decomposed pine bark and vermiculite (CS), carbonized rice husk with different particle sizes (CAC1: Greater than 2 mm, CAC2: 1 - 2 mm, CAC3 0.5 - 1 mm and CAC4: Lower than 0.5 mm), coconut fiber (CF) and vermiculite (VM). Tubes of 55 cm3 were used for seedling formation. The plants remained in a greenhouse for 60 days and 30 days in full-sun exposure. We evaluated: Height, stem diameter, shoot dry mass, root dry weight, ease of removal from the tubes, aggregation of roots to the substrate and height-stem diameter relationship. It was concluded that the substrate consisting of pure CAC, in different particle sizes and mixed to the other components, is technically feasible for the production of Eucalyptus camaldulensis seedlings, while those formed by mixing 50% of CAC and VM resulted in increased growth of the seedlings. The properties of the substrates, bulk density, pH and cation exchange capacity, are important in the production of seedlings; they showed significant correlations with the biometric variables.