Abstract:

93 15-year-old trees from the 31 provenances trial stand in Nanyu Forest Farm of Fujian Province were collected to deal with variations in bending properties of wood (modulus of elasticity and modulus of rupture) for exotic Loblolly Pine (Pinus teada) and their relationships to trees age, latewood percent and wood density in this paper. The range of rings for all test samples in radial direction within trees were marked. MOE for these provenances was from 5 042.5 to 8 610.2 Mpa and their average value was 6 702.6 Mpa. And MOR was 77.32 to 119.79 Mpa and 99.11 Mpa in order. It was found that MOE and MOR varied markedly among 31 Loblolly Pine provenances. Their broad sense heritabilities were greater than 0.441 and 0.422 respectively according to variance analyses. And genetic factor accounted of 43.07%～60.79% in different periods of tree growth and environment factor 39.21%～ 56.93%. Consequently,apart from a medium level of genetic control,MOE and MOR were also affected by growing environment. Variation coefficients of MOE and MOR within a given provenance were greater than those among provenances. This indicated that single tree selection within a provenance on the basis of selection among provenances is beneficial to wood quality. MOE and MOR were significant positively related to tree age, latewood percent and wood density. Wood density could be a best factor used for predicting MOE and MOR in wood improvement. Values of MOE and MOR for Loblolly Pine provenance were distinct related to its culturing environment. In this trial stand, MOE and MOR for Loblolly Pine provenance were not related to altitude of its provenances in its indigenous districts in USA and were markedly affected by their latitude. Among eight factors of latitude,longitude,the lowest temperature of January,annual mean temperature,total summer rainfall from June to September,annual rainfall,the proportion of total summer rainfall to annual rainfall and frostfree season of local geography and meteorology in USA,longitude is the most important factor in effecting bending properties of wood (MOE and MOR). Next is the proportion of total summer rainfall to annual rainfall. Other factors had no any effects on MOE and MOR.

Key words: Loblolly Pine, provenances, MOE and MOR, wood density, latewood percent, tree age, genetic variation, environment