Seedling Morphological Characteristics on Survival, Uniformity, and Growth during a Full Short Rotation in Eucalyptus grandis x E. urophylla Plantation

Abstract

The objective of this work was to evaluate the losses in the process, survival, uniformity and growth during an entire short rotation of a clonal planting of Eucalyptus grandis x Eucalyptus urophylla in Brazil as a function of the different morphological characteristics of the seedlings considered a proxy of seedling quality. Seedlings were classified in descending order of quality by the following treatments: A > B > C. Treatment D was composed of prime seedlings 180 days old in the nursery. Treatment A and B experienced a mortality rate of 3% 30 days after planting, while seedlings C and D showed a mortality rate of 8%. Throughout the entire planting process, treatment C had the highest total losses of 24%, which was 15% higher than the average of the other three treatments. The quality of seedlings, as determined by the IQD, positively correlated with stem diameter, leaf biomass, and PH50 at 60 days of age. However, these relationships lost significance at later ages, and the DQI could not explain the variation in volume and stand uniformity (PV50) along the rotation. Despite early differences, from 36 to 64 months, only old seedlings (Treat. D) showed a difference in wood volume to the other treatments.