Genetic Variation in the Microfibril Angle of Loblolly Pine From Two Test Sites

111 rec en/ \cJcrrr, \e>vrr(rl ttrrclrer have rucrri~rrrt~cl t r ~ c>ffec.t of nirc rojrbrrl er11,ylr (MFA) on ~ o o d q~rnlrt\ Hov~~rv~i, , lrttle rr>reare 11 hor I?oc~n corldr(ctt~d r(poir the ymetrt nzc2r hanrrilrr c oi1trollrilg MFA. 111 thrr \trltl~, we rrrrrrlrrzcd the Izcrrtahrlrr\~ of MFA rrr lo l~ lo l l~ prize, Plnus taeda L., crnd r r r g~nrtrc iulutron\hrpr ~'rtlz herglzt, clrcrrneter, vo l~ t r~e , ctnd ,per. ~ f r c ginvrt\ Inc rc>nlrnt ( or<.\ we1 P t ol1cctc.d clt hrcw\t herght from 20 to 25 proKen\ fron7 each of 12 to I7 c rosser (crinong I I parerit\) 112 trvo n~odrfiecl partrul-d~ullels rrz cl~fferent loccxtronr rn \outher11 Arhtri7\mr. Specific gmvrty war inerrrured on \rgmentr coi1turnrng rrngr I through 5 ~ n r l on \~gmentr coirtarnrng rrngr 6 through 20 MFA wtrc metrrured on the e a r l ~ ~ ~ ~ o o c l and atewood tectronr of rrng\ 4, 5, 19, trnrl 20 Rrng, 4 crnd 5 wer*e cl7osoir t r r reprrrentc~trve of tort' wood and rrngr 19 trrrd 20 ur repre~teiztatr~~c~ o f outer wood. Anul) re\ of vcrrraire cJ revc~aled rtcrtr S ~ I ~ L I I I J rrgr~~frcczi~t genptzc and envrronrneiitul rnfluerzt e\ 011 MFA. Srgnrfrcrli1t ,ycr~erc~l corizr">ri~rng rrl?rlrr~ (GCA), \l?ecr/ic coinbrrzrng uhrlrt~ (SCA), ernd SCA X block e/fec.fr riielrce~tecl that there c~re hot11 ~ c l c l z t ~ ~ ) ~ (2nd r onmcldrrrvr genc.tic ri~flueiic er on MFA Ir~clrvrtlucrl-trw, ii(~rrn\+~-\erz\c~ Ir~rit~rh~lrt) (>\trrne7t~r v~~ort' vancrble, rrrngrng jroin 0 17for ee~t-IYrtood (nizg) 4 MFA to 0 51 for r~arl\~~oocl (rrng) 20 MFA Genetre c orrelrrtronr hctccrcw MEA, rpec r f r c gr~zvrt), errzd thr growtlz tr(rrtr it'rre izon\rgr~rfrccint to l c ~ r g ~ e t r ~ ~ ~ c r t ~ d rtanrlcrrcl rrmrr. Sor~tk. J AppI For 28(4) 196-204.