Genetic Variation of Wood Density and Its Relationship with Drill Resistance in Shortleaf Pine

Wood density is an important wood quality trait, but inexpensive, reliable, and rapid methods for assessing it are lacking. A new device called the Resistograph has the potential for rapid assessment wood density of standing trees. The relationship between wood density and drill resistance measured by a Resistograph was investigated in a shortleaf pine (Pinus echinataMill.) population in Missouri at the age of 25 years. At the individual-tree level the linear relationship between wood density and drill resistance (amplitude) was weak and positive (R2= 0.23) but was stronger (R2 = 0.47) at the family mean level. Genetic relationship between the two traits was moderately strong (r A = 0.74). Individual-tree heritability estimates for both traits were high (h2 = 0.47 for wood density and h2 = 0.64 for amplitude). The efficiency of using the Resistograph to indirectly select for improvement of wood density was 86% at individual-tree level, suggesting that the Resistograph could reliably be used to assess wood density in live shortleaf pine trees.