Determination and genetic analysis of resin productivity, resin density and turpentine content in halfsib families of slash pine

To accurately measure the variation of resin productivity, resin density and turpentine content from 49 openpollinated families of slash pine (Pinus elliottii), an improved resin collection and distillation method and device was used for the data collection. Genetic analysis of the halfsib family data showed highly significant differences in resin productivity, DBH (diameter at breast height) and resin basic density among the families (P0.01); the estimated family heritability for resin productivity, DBH and resin basic density was 0.798, 0.436 and 0.337, respectively, with corresponding estimated individual heritability 0.685, 0.368 and 0.295. There was a significant positive genetic correlation (r=0.540, P0.01) between resin productivity and resin basic density, while a significant negative genetic correlation (r=-0.838, P0.01) between turpentine content and resin basic density. The turpentine content is an important resin quality indicator. Resin productivity multiplied by turpentine content percentage, which was designated as turpentine production index, was used to estimate the genetic gain for selection and four superior families with higher turpentine production index were selected.