EUCALYPT DRYING and COLLAPSE

One of the challenges regularly encountered by eucalypt processors is defects which occur during drying. If eucalypt wood is to used for high-value solid wood products, it is crucial to understand defects such as cell collapse during drying.

A recent PhD project sought to shed some light on drying defects. Student Vikash Ghilidiyal, from India, completed his PhD on this topic in 2023.

His results indicate that heartwood collapse is under genetic control in both E. globoidea and E. quadrangulata with the heritability ranging from 0.19-0.44. Heartwood collapse was negatively correlated with basic density and positively correlated with extractive content. The collapse was lower in the sapwood than in the heartwood.

Vikash concluded that collapse in this future eucalypt resource can be minimised through breeding, potentially eliminating the problem. This finding is of value to the NZDFI breeding programme, where future selections can incorporate resistance to drying defects.

Vikash has so far produced two refereed publications:

• "Genetic variation in drying collapse and heartwood properties at mid-rotation age of Eucalyptus globoidea"
• "The effect of Joule heating on collapse and water absorption of wood"

Vikash's 2023 PhD thesis is available here: 'Understanding and reducing drying collapse in difficult-to-dry plantation-grown eucalypt timber.'