Session 5: Advances in Plant Sciences

Transcription

1 Dhl Gedge Iel Sympum Se 5: Advce Pl Scece HYDRAULIC CONDUCTANCE TRAIT TO IMPROVE CROP YIELD IN WATER-DEFICIT ENVIRONMENTS Thm R. Scl Uvey f Fld, Gevlle, FL, USA, d Nh Cl Se Uvey, Rlegh, NC, USA ABSTRACT Sce hum hve bee wg eed, gl h fe bee mxmze yeld f he we vlble. Th ppe evew he fc h fluece he elhp bewee yeld d we ue, d he exme lu h mgh cbue mde yeld cee fxed mu f we. The phyc f g exchge by leve mpe lm he elhp bewee pl gwh d p we l. Bh we upke by he pl upp p d he we l dve by mphec vp peue defc (VPD) ply mj le deemg mxmum cp yeld gve evme. Thee e blgcl lu bek h phycl elhp me he phc f geec ppche. Hweve, hee he pbly cheve mde yeld cee by develpg pl mmze lef g exchge,.e. p d CO ml, dug ped whe VPD hgh. I ece ude, ybe geype PI w fud hve cued cee p e VPD ceed bu kp. Rhe, he m f h geype cled hgh VPD d med c p e. Whle m clue lm CO ml, mp dvge h l we ceved h vlble le he gwg e f cp ue whe we-defc cd develp. The b f h

2 158 Cp Pduc he 1 Ceuy w ced lw hydulc cducce he leve f PI Feld e wh dvced beedg mel d evmel ly hve hw h h eul ceed yeld ve wde ge f evme. Seed f hgh-yeldg geype wh he we-vg e w beg cped m cmmecl beedg pgm he U.S. BACKGROUND Suffce we gw pl w lkely mj cce fe hum wed he f eed. Cely mj fc he develpme f ely hum cvlz w eed gze peple mge we euce f cp pduc. Wh he dve f mde cece e f he f expeme wh pl w e f bev he f pl gwh we ue (Wdwd, 1699). Abu e huded ye g, hee w emedu cvy wld-wde qufy he. (Acully, hee ude eped he he 'we equeme' defed he vee gwh we ued.) Mj pjec wee udeke U.S. Nebk by T.A. Keelbch (191), Wc by F.H. Kg (1914), d Cld by L.J. Bgg d H.L. Shz (1913, 1917). The eul f hee ude hwed h we ue by pl w vey much evmel depede d h hee wee dffeece mg pece. Ideed, Bgg d Shz (1913) ccluded h The mlle, ghum, d c gup hve bee fud he m effce, whle lflf d wee clve e le effce pducg dy me wh gve mu f we. The mll-g cp hve we equeme emede bewee he legume d c.ǁ Thee cclu wee cfmed dew' 1958 clcl ly f much f h ely d cp we ue. He fud h he f pl gwh (G) ped we l (T),.e. p we ue effcecy, w clely defed ve wde ge f cd by he fllwg mple equ. G / T = m / E, (1) whee m = empcl ceffce d E mphec we demd, uully meued ug pe p f we. The vlue f m ved mg pece excly ccluded by Bgg d Shz (1913). Te d Scl (1983) mved Eq [1] fm empcl elhp mechc e. The heeclly deved elhp fllw. G / T = k / VPD () whee VPD mphec vp peue defc d k defed belw. k = b c (P C / 1.5 ρ ε (L d / L T ). All vble defg k e eelly c excep f b d c. The vble b decbe he cve ceffce f phyhe pl cmpe d pmly depede f he cbhyde, pe, d lpd cmp f he pl pduc. The vble c deped

3 Dhl Gedge Iel Sympum whehe pl pece h he pecu gc cd phwy (C4) phyhe. Ule m egul by el lef CO, he vlue f c hve mxmum vlue f bu.3 f C3 pece d.7 f C4 pece. Bed bh heecl d expemel lye, he vlue f k eelly c f y gve pl pece. A exmple, he vlue f k f he C4 ge 9 P, f C3 ge 6 P, d f legume 5 P. Thee vlue e excly ce wh he cclu f Bgg d Shz (1913) d dew (1958). YIELD AND WATER The lm pl m pduc bed we vlbly f pl ue p edly defed by egg Eq []. G < T k / VPD (3) Eq [3] hw clely h pl m lely depede he mu f we pl c upke f p. Al, h equ llued he ccl le h mphec VPD ply lmg yeld. I dy clme wh eleved VPD, he gwh f he pl ecely lmed lwe level. F exmple, he gph belw hw he chge fll d VPD gg fm we e he Ge Pl e f Nebk (Fg. 1). N ly de he wee de f he e uffe fm lw fll, bu he hgh VPD fuhe decee pel pl gwh. R f l l ( m m ) Nebk: Me (15 Ju 15 Sep) 3.4 VPD R V ep D f c P u e k e P 挀 ) 㨀 Fgue 1: Rfll d vp peue defc dug umme gwg e x cue he e f Nebk, gg we (lef de) e (gh de). 15 l l h k 1.4 K m b c M e l D u g K e e C u e l B u Cuy Eq [3] c be expded defe he lm yeld (Y) whe ly p f he pl e hveed. F g cp, hve dex (HI) he f g yeld l pl yeld h c be ued clcule lm hveed yeld.

4 16 Cp Pduc he 1 Ceuy Y = HI G < HI T k /VPD (4) F m dugh u h e elev gculue, dvced culv hve HI' h e ely eve we-defc cd. I he pece h hve HI eve wedefc, uch ce, yeld pge pble by eekg geype h hve bly HI. The depedece f yeld he evme c be edly eved fm gph bed Eq [4]. Yeld lm lely eled we vlbly d veely eled VPD. Sce h phycl elhp, leg h lm meble geec le f he pl. Ude cd f lw we vlbly, hee hd lm mxmum cp yeld (Fg. ). ) - 1 Y e l d ( h Sybe (HI =.4) VPD (kp) = Fgue : Mxmum ybe yeld ude vu vp peue defc evme fuc f pble l we Tpble We (mm) A cle Fg., y mp mgeme ppche h cee he mu f we vlble pl f upke cee T wll cee he lm yeld. Geec mpveme h llw cce me we he l, e.g., deep g, wll e he lm yeld. Nevehele, ude we-defc cd yeld wll be ced d geec mpul -- me hw phced-- wll bek he lm defed Equ [4]. Oe leve h fe de ee he dcu f ceg cp yeld we-lmed evme he vble VPD. Of cue, key fc he gwh f my mll g he bly gw cle e f he ye whe by def VPD lwe. Theefe elec f cl-le geec mel p f ceg cp yeld me we- defc evme. Whle he vlue f VPD evmel fc beyd blgcl cl, we hve becme eeed he pbly f pl ecg VPD he effecve VPD f p deceed. Th c be cheved by deceg pl g exchge whe VPD hgh h he fc f l pl g exchge h ccu hfed lwe vege VPD. The

5 Dhl Gedge Iel Sympum bevble cequece f uch egy wuld be mddy m clue. Ahe beef dd cee Y/T wuld be he eulg l we cev h culd be ued le he e u cp gwh dug le-e ped f we defc. We hve becme cve he egul f cp g exchge eul f evy VPD. TRANSPIRATION REGULATION BY PLANT HYDRAULICS Pu (198) pped lm whe p by elecg geype wh mll dmee xylem eleme eulg deceed hydulc cducce. Succe w cheved defyg geype wh mll dmee eleme h ceved l we, h w eve dvced f ue cmmecl gemplm. A pble lm f h mcl ppch deceed hydulc cducce h mgh eul lmed p d CO ml ude ge f cd. We beg u ude defy pble hydulc egul f p by vegg he ybe geype PI , whch expee delyed wlg ude we-defc cd he feld. We hyphezed h he delyed wlg pheype w cue f l we cev eulg fm lwe m cducce. The f ep u veg w exme he epe f T ceg VPD ud he h. A yem w develped h llwed 1 pl be exped ge f VPD dug gle expeme. Whle T lw VPD f PI w he me he culv, he eul wee que dffee hgh VPD (Fleche e l., 7). I c he geype whch T ceed lely ve he whle ge f eed VPD, PI hee w bekp bu kp bve whch hee w lle fuhe cee T (Fg. 3). ) 1 - p m - H ) A5959 T = (VPD) R = b) Ghm T = (VPD) R = ( T m g ) 1 c) PI d) PI R =.97 If VPD <.13, T = (VPD) If VPD.13, T = (VPD) 75 5 T = (VPD) R = m ᰀ p - H T m g ( VPD (kp) VPD (kp) 3 4 Fgue 3: Tp e f fu ybe geype ve ge f vp peue defc (Fleche e l., 7).

6 16 Cp Pduc he 1 Ceuy C T VPD gee h kp mgh eul fm lmg hydulc cducce he 4 pl h culd. 8upply we he m gud cell uffce e u he we l e hgh VPD. T exme he pbly f hydulc lm PI , Blx - Peue expeme.6 exme he VPD epe whe pble hydulc lm he w de d h wee vecme. I h expeme, p f ybe pl wee eled 1.87 peue chmbe.4 d peue w ppled h he xylem pel he lef pele w ze. p A peue duce w ched pele h he peue ud he p w T. cuuly djued me he VPD eme h he lef xylem pel w.5 med ze. Supgly, he epe f he pl VPD w uchged eve hugh y pble lm by d h hydulc cducce w vedde (Fg. 3) (Scl e l., 8). Thee eul wee epeed VP Ddce f hee w hydulc lm hd ex he leve bewee he pele xylem d he gud cell. ue 4 T elve he hyphe h PI mgh hve uuully lw hydulc cducce.8 he lef, w expeme wee udeke (Scl e l., 8). The f expeme w.6 mply cu he pele f leve udewe f c leve d 1.8 ck he g exchge ve clue me. The f m ccep becue h f he he mechcl uge f dvge we f he epdeml leve cell cu uudg g w he u l d e ul pd gud cell..ideed, he pele-cug expeme euled he f pd m A Peue clue cl ybe geype (Fg. 5). O he he hd, he f ml p T clue PI w delyed d he e f clue w le h he he geype Thee eul cded lwe hydulc cducce he leve f PI VPD ue 4 T p PI - Peue VPD Fgue 4: Tp e v. vp peue defc f PI whe lef xylem w med ze pel by ecg p peue chmbe (Scl e l., 8).

7 Dhl Gedge Iel Sympum e x c h g e R PI A5959 Blx Fgue 5: Cb dxde ml fllwg cug f pele ude we me ze (Scl e l., 8). E O.5 l. C.5 R e Tme () I he ecd expeme, pele f lghly dehyded leve wee cu d mmedely ceced we uce. The e f we flw he leve w meued. The me c f flw PI w much le h f he he culv g dcg hydulc lm he leve (Fg. 6). O-gg expeme e empg exme he b f he ppely lwe lef hydulc cducce PI Reul de d hw y bvu, ce mcl dffeece he leve f PI cmped he ybe le. Sude e w beg udeke deeme f he qup ppul cvy he hydulc phwy leve ccu f he ppe uuully lw lef hydulc cducce PI Fgue 6: Hlf lfe f we mveme lghly dehyded leve fe pele wee cu ude we (Scl e l., 8). YIELD AND TRANSPIRATION REGULATION The c f lw lef hydulc cducce PI wh he uuul epe VPD d he delyed wlg pheype gug. Hweve, ukw whehe h h wuld cee Y/T d ceve l we wuld cully cbue yeld cee

8 164 Cp Pduc he 1 Ceuy he feld. The beefcl de f h ffe by he l f CO ml ll he me whe VPD exceed kp. If ped f we defc develp le he e whe he ceved l we culd be ued dvge, he yeld l culd be pedced fm h. Fuely, D. Tmmy Ce (ARS-USDA, Rlegh, NC) ed beedg eff fe he delyed-wlg pheype hgh yeld ybe le. T de, D. Ce h eed w le h hve cely gee yeld h hgh yeldg cmmecl culv we-defc cd. A hgh yeld level, he yeld f hee w delyed-wlg pheype ppe hve lle decee yeld cmped he hgh yeldg cmmecl le. Thee w le e w feely vlble pve, cmmecl ybe beede he U.S. f ue he beedg pgm. Thee em que bu whee d hw fe culd ybe pduce expec yeld g fm cmmecl culv wh he delyed-wlg. We e vlved cpeve evme ly wh Pee H-bed Seed cmpy (Chle Me, Jh, IA) elve hee que. Pee h develped GIS d be f he ee U.S. cp e by dvdg he cuy 8 gd f 3 km x 3 km dme. A le 5 ye wehe d be h bee develped f ech gd. The wehe d e w ued mule ybe yeld ech ye ug elvely mple, mechc mdel f ybe develpme, gwh, d yeld. The mdel muled gwh, cp we l e, d l we blce e-hu me ep. F, yeld f 'ml' ybe cp w muled ech f he 5 ye f ech gd (>14, mul u). The mul wee he epeed wh djume he mdel m c mxmum p e d CO ml e y me ep whe VPD exceeded kp. Supgly, he pved cee yeld ely ll eg f he U.S. me h 75% f he ye. Whle he f evy VPD eul f he ppe lw lef hydulc cducvy epeclly ueful me eg, hee eul dce h mgh be ccepble ll eg f he U.S. Eve he ye whe he w muled eul yeld l, he yeld decee w uully que mll. Sybe pduce wll hve he fm mke k dec bu he pbly f yeld cee m ye he pce f mll yeld decee he wee ye. The ehum f cp f he delyed-wlg cmmecl beedg pgm mke eem lkely h ybe culv c he U.S. wll be pducg mde yeld cee eul f wh ppe be deceed hydulc cducce he leve

9 Dhl Gedge Iel Sympum REFERENCES Bgg, L.J. d H.L. Shz The we equeme f pl: II. A evew f he leue. USDA Bueu Pl Iduy Bull. 85. Bgg, L.J. d H. L. Shz, The we equeme f pl flueced by evme. Pc. d P-Am Sc Cg. 3, Whg, D.C. Fleche, A.L., T.R. Scl, d L.H. Alle, J. 7. Tp epe vp peue defc well weed 'lw wlg' d cmmecl ybe. Ev. Exp. By. 61, Keelbck, T.A Tp expeme wh he c pl. Nebk Agc. Exp. S. 3 d Au. Rep. P , Lcl, NE. Kg, F.H Sl Mgeme. Oge Judd C., Ld. Scl, T.R., M.A. Zweeck, d N.M. Hlbk. 8. Lw lef hydulc cducce ced wh dugh lece ybe. Phylg Plum. 13, Te, C.B. d T.R. Scl Effce we ue cp pduc: Reech eech? I: H.M. Tyl, W.R. Jd, d T.R. Scl (Ed), Lm Effce We Ue Cp Pduc. Am. Sc. Agmy, Md, WI. Wdwd, J Sme hugh d expeme cceg vege. Phl. T. Ryl Sc. Ld. 1,