| Slash pine (Pinus elliottii Engelm.) from the southern United States is a worldwideimportant plantation species for timber and resin production. It was introduced into China since1930s’, and has been widely planted in the subtropical region, with the standing forest areaover2million hectares. In the past years, the breeding works on the species have been carriedout in China mainly focused on the improvement of stand growth and wood property, but lessattention on the resin production traits that is once regarded as by-product with timberproduction.Based on the standardization of resin sampling methods and instruments, some specificobjectives was carried on:(1) the genetic variation in resin production ability and resincompotents among slash pine families,(2) the resin production ability correlation betweenjuvenile and mature slash pine families, and (3) the determiantion of the early indirect selectionindictor related with the growth and photosynthesis. This study is dedicated to elucidation ofthe theoretical foundation of elite variety selection of slash pine for resin production. Theresearch results are described as below:(1) Genetic analysis on the49open-pollinated families test stand shows there are highlysignificant differences (p<0.01) in resin productivity and DBH among the families; theestimated family heritability for the two traits values0.798,0.436, respectively, and thecorresponding individual heritability is0.685,0.368. There is no significant genetic correlation(r=0.54, P<0.01) between resin productivity and DBH. The heritability of resin density alsostand on the high level. Using the theory resin yield index which is resin productivity abilitymultiplied by DBH, five superior families with higher resin yield are selected with theestimated genetic gain between120%-251%.(2) Totally98individual trees from38open-pollinated families are sampled for thedetermination of resin components and the genetic variation pattern study. The result shows that there are mainly10kinds of monoterpene ingredients and20kinds of resin acids,accounting for about10.121%and88.604%of slash pine resin. Genetic analysis based onANOVA shows the family effect has a strong significant (p<0.01) with turpentine oil content,α-pinene and β-pinene with the corresponding estimated family heritability of0.515,0.495and0.533. There is a significant negative correlation (r=-0.46, p<0.01) between α-pinene andβ-pinene.4of resin acid ingredients have a strong significant family effect with the estimatedfamily heritability of0.611-0.812. With10%of selection differential, the high content slashpine families with those main components are selected.(3) The feasibility of early selection on resin production traits has been explored in orderto advance the time of germplasm evaluation and improve the selection efficiency. The potted4a seedlings and19a test stand trees of eight families are measured as young and adult samples.The result shows that both resin productivity and DBH growth has a strong significant age-agecorrelation, with the correlation coefficient of0.664and0.689respectively. As a result, it’sfeasible and reliable for the early selection on high resin production. However, there are nosignificant age-age correlation among the constituent traits, including the content ofmonoterpene and diterpenes, even most of the single main components.(4) The correlation between photosynthetic characteristics and resin production abilitywas elucidated based on the4a potted seedling with the8slash pine families. It shows that thediurnal change of net photosynthetic rate is a doublepeak curve, the differences withphotosynthetic physiological characteristics among families are extremely significant, exceptfor the transpiration rate. The net photosynthetic efficiency shows a highly significant positivecorrlation with resin productivity and DBH growth with the correlation coefficient of0.500and0.742, respectively. Therefor it is advisable to evaluate elite variaties with the high resinproduction at the young slash pine by photosynthetic efficiency indictors. |
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