Keywords: Chlorophyll fluorescence, Fragaria ananassa, light recovery, shanding stress

Transcription

1 Avne Journl of Foo Siene n Tehnology 5(6): , 23 ISSN: ; e-issn: Mxwell Sientifi Orgniztion, 23 Sumitte: Mrh, 23 Aepte: Mrh 27, 23 Pulishe: June 5, 23 Effets of Shing Stress n Light Reovery on the Photosynthesis Chrteristi n Chlorophyll Fluoresene Chrteristi of Frgri Annss Duh. v. Toyonok, 2 Renyn Dun, Minyi Hung, Zhigo Wng, Zhongxin Zhng n 2 Weiyi Fn Shool of Life Siene, Anqing Tehers College, Anqing, Anhui 246, Chin 2 College of Life Siene, Shnxi Norml University, Xi n, 762, Chin Astrt: Light is n importnt resoure for plnt growth n evelopment, rops nee to hnge their physiologil hrteristis to ifferent light environments. Frgri nnss Duh. v. Toyonok. is n importnt eonomi plnt whih is wiely plnte t home. A greenhouse experiment ws onute from April 2 with ifferent sun-shing tretment, 85% (CK), 6% (T ), 35% (T 2 ) n % (T 3 ). After 7 ys of shing stress, the physiologil hrteristis were slowly reovere. The results showe tht () Uner shing onition, Light sturtion rte (Amx), Apprent Quntum Yiel (AQY), Croxyltion Effiieny (CE), rk respirtion (R), Light Sturtion Point (LSP) n Light Compenstion Point (LCP) eme lower. (2) The mximl fluoresene (Fm), light energy trnsformtion effiieny of PS II (Fv/Fm), tul photohemil effiieny of PS II in the light (Yiel), photohemil quenhing oeffiient (qp) eline with shing stress inrese. (3) There were signifint ifferene in the hlorophyll fluoresene prmeters mong ifferent tretment groups y the en of sun-shing tretment (p<.5). After the light ws reovere, the physiologil hrteristis oul rpily reover uner low shing stress n moerte shing stress, while in severe shing stress the physiologil hrteristis hrly reover. Keywors: Chlorophyll fluoresene, Frgri nnss, light reovery, shning stress INTRODUCTION There is ro onsensus in eology tht light is n importnt resoure for the survivl, growth n istriution of rops (Jensen et l., 22). In ifferent time n spe onitions, the Photosyntheti Photon Flux Density (PPFD) is ifferent, n rops nee to evelop limtion n plstiity mehnism to ope with the vrying light regimes y hnging their morphologil n physiologil pttions to ifferent light environments (Ginoli n Vllres, 22; Wyk et l., 22). During plnting, most rops re expose to ifferent light grients (from full she to full exposure to sun light), n plnts re esily sujete to t lest some egree of she. In response to shing, exmples for n tive type of plstiity re n inrese in speifi lef re (Delgrnge, 2), in lef size (Vllres n Pery, 998), or the elongtion of internoes (Vn Kleunen n Fisher, 25). In orer to help lne the light sorption etween the two photo-systems (PSI n PSII), she leves hve lower hlorophyll / rtio (Chzon, 992). In lower light environment, rops my hnge lef struture n physiology, whih etermines the lef ron quisition n gs exhnge (Ginoli n Vllres, 22; Wyk et l., 22). Some stuies on response of photosyntheti plstiity to hnge light environments minly fouse on speifi light environment, suh s rtifiil elines ifferent ense she t lortory experiment (Feijó et l., 29) n some pthes (suh s gp n non-gp; gp, non-gp n expning gp) t outoor experiment (Shimtni n Kuot, 2). However, previous stuies on response of photosyntheti plstiity to ifferent stle light environments hve file to ynmi hnges of light environment, suh s shing stress n light reovery (Oguhi et l., 26; Feijó et l., 29; Shimtni n Kuot, 2). So, further stuies re still essentil. Chlorophyll fluoresene tehnique provies rpi n non-intrusive proe for the mesurement of photosyntheti funtion uner ifferent light onition in reent yers (Rzvi et l., 28). Frgri nnss Duh. v. Toyonok is n importnt eonomi plnt whih is wiely plnte t home n ro, n esily suffers the effet of light stress. It ws wiely ultivte in our ountry. How oes its physiologil proess ret with the hnging light environment? How n in wht extent oes its physiologil plstiity response to hnge of light environment n light reovery? Bse on our oservtions, we hypothesize tht: The physiologil proess of F. nnss is sensitive to hnges in the light environment Corresponing Author: Renyn Dun, Shool of Life Siene, Anqing Tehers College, Anqing, Anhui 246, Chin, Tel.:

2 Av. J. Foo Si. Tehnol., 5(6): , 23 It is e esily reovere in lower shing stress fter the light ws reovere, while it is hrly reovere in severer shing stress. The ojetive of our stuy is to eluite the reltionship etween photosyntheti plstiity n light environment of the F. nnss n to test the ove hypotheses. MATERIALS AND METHODS The experiment ws onute t Anqing Botnil Gren, whih is lote in the western suur of Anqing. These seelings of one yer-ol originlly were grown in greenhouse in the erly spring of 2. Then they were trnsferre to ontrol light (out 85% of full mient light) t the eginning of April 2. At the en of April of 28, these potte seelings were ivie t rnom into four groups, with eh group omprising three potte seelings. Eh of the three groups ws sujete to one of the four ifferent light environments (ontrol-, mil-, moerten severe-stress). The seelings were irrigte t regulr perios epening on the wether n soil moisture sttus. Methos: For ssessment of light effets on the physiologil hrteristis of F. nnss, light grient ws estlishe using ifferent lyers of neutrl guze to provie four levels of visile light: ontrol light (CK, out 85% of full mient sunlight), mil stress (T, out 6% of full mient sunlight), moerte stress (T 2, out 35% of full mient sunlight), severe stress (T 3, out % of full mient sunlight). After 7 ys of light stress, the lights of seelings were reovere until the th y. Mesurements of net photosyntheti rte (P n ), stomt onutne (g s ), trnspirtion rte (T r ), interellulr CO 2 onentrtion (C i ), respirtory rte et. were rrie out uner mient/ontrolle onitions with portle photosynthesis mesurement system (LI-64, LI-COR In. Linoln, NE, USA). A 2 3 m hmer ws use n LED 64-2B lmp provie the light soure. All mesurements were performe from 8: to : m. Light-response urves were rete with eleven levels of PPFD (, 5, 25, 5,, 2, 4, 6, 8,,,,2 μmol photons/m 2.s) in eresing orer. The time llowe etween eh reing ws 2-3 min intervls. All mesure leves were lote in mile to upper prts of one fully expne n mture lef. Mesurements were me t temperture of 25 C n CO 2 onentrtion of 4 ppm. The Light sturtion rte (Amx), Apprent Quntum Yiel (AQY), Croxyltion Effiieny (CE), rk respirtion (R ) n Light Compenstion Point (LCP) ws lulte (Wng et l., 24). The smple lef ws ple in the urette until t lest five stle reings were otine. At vrious time intervls uring the shing tretment n the reovery, the in vivo hlorophyll fluoresene of PSII ws mesure y pulsemoulte fluorometer (PAM-2, Wlz, Effeltrih, Germny) onnete to omputer with ontrol softwre. For onseutive mesurement of hlorophyll fluoresene prmeters, we mrke fixe position in eh smple lef. In orer to mesure the miniml Fluoresene (F ) n mximl fluoresene prmeters (F m ), the smple ws first rk pte for t lest 2 min using lef lip. At nture light, we mesure the miniml fluoresene (F ) n mximl fluoresene prmeters (F m ). The following fluoresene prmeters were lulte: vrile fluoresene (rk) (F v = F m -F ), mximl photohemil effiieny of PSII (rk pte lef)(f v /F m ); vrile fluoresene (light) (F v = F m - F ), photohemil effiieny of PSII in the light, whih is the effiieny if ll retion enters remin open (F v /F m ); tul photohemil effiieny of PSII in the light, whih is the effiieny uner the tul egree of retion enter losure ((F m -/F)/F m ); the pprent Eletron Trnsport Rte (ETR = F/F m PPFD.5.84) (Rzvi et l., 28). There re two kins of fluoresene quenhing, suh s photohemil quenhing (qp) (qp = /(F m - F)/(F m -F )) n non-photohemil quenhing (qn) (qn = -(F m -F )/(F m -F ) = -F v /F v ). All t were plotte using MICROSOFT EXCEL 23, n eh vlue of men n S.D. (stnr evition) in the figures represents t lest 3 replitions of mesurements. A one-wy ANOVA ws use to evlute ifferenes of hlorophyll fluoresene hrteristis of F. Anmos of shing stress n light reovery. Signifint ifferenes isusse hve proility (p) vlue <.5. RESULTS AND DISCUSSION In the wek intensity rnge (~6 μmol/m 2 s), the photosyntheti rte (P n ) of oth the she n unshing leves hs rpi inrese. There were little ifferenes etween ifferent tretments (p>.5). When the light intensity is greter thn 6 μmol/m 2 s, with the inrese of light intensity, the photosyntheti rte (P n ) ten to e stle, n the ifferene etween the tretment inrese. The photosyntheti rte of ontrol leves is higher signifintly thn tht of the she leves (p<.5) (Fig. ). This suggests tht in low light intensity, shing hs no signifint influene on strwerry 788

3 Av. J. Foo Si. Tehnol., 5(6): , 23 Fig. : Light-response urves uner ifferent shing stress photosyntheti rte. However, with light intensity inrese, the influene of the she inreses signifintly. In Fig. 2, ompre with the nture light, ifferent shing strength reue signifintly the Lightsturte photosyntheti rte (A mx ), Apprent Quntum Yiel (AQY), Croxyltion Effiieny (CE), Light Sturtion Point (LSP), Light Compenstion Point (LCP) n rk respirtion rte(r) (p<.5), exept some prmeters, suh s AQY n LCP h no signifint ifferene uner mil stress n moerte stress (p>.5). After the light ws reovere, the physiologil hrteristis oul rpily reover uner low shing stress n moerte shing stress, while in severe shing stress the physiologil hrteristis hrly reover (Fig. 2). The F is fluoresene yiel when PSII retion enter is totlly open (Feijó et l., 29). From piture 3-A, we know F stys the sme level silly when given norml light. Uner the sme shing stress, with the stress time inrese, the hnge of F whih uner moerte stress n severe stress hs ertin turning, tht is: it firstly expresse slight erese n then hs growing teneny. With the egree of stress serious, the turning point hs n vne teneny. Amx A AQY.2.5. B CE C R 2.5 D LSP E LCP F Fig. 2: Effets of shing stress n light reovery on the photosynthesis hrteristi of Frgri nnss the ifferent letters inite sttistilly signifint ifferenes t p<.5 etween elevtions Shing stress Light reovery 789

4 Av. J. Foo Si. Tehnol., 5(6): , A B.2 C Amx 2 5 AQY.2.5. CE R 2.5 D LSP E LCP F Fig. 3: The omprison of hlorophyll fluoresene prmeters etween shing stress n light reovery the ifferent letters inite sttistilly signifint ifferenes t p<.5 etween elevtions Shing stress Light reovery The turning point omes on the 4th y when uner moerte stress n on the 3r y uner severe stress. Mil stress hs lwys slowly eline teneny. Others oul e le to reover the norml level n there were no signifint ifferenes etween them (p>.5) (Fig. 3A). The non-photohemil energy issiption of PSII ntenn pigment le to the eline of F, while the PSII retion enter whih suffers mge or reversile intivtion rouse n inrese in F. This reserh showe tht oth moerte shing stress n severe shing stress rouse F erese firstly n then inrese. It tol tht the eline of energy whih ws sore y PSII ntenn pigment flew own into prt of photohemistry n the energy inrese in the form of het issiption n fluoresene (Feijó et l., 29). With the shing stress time protrte, the photosyntheti struture of strwerry lef suffers mge to ertin egree. Besies, the turning point of F omes erlier with the egree of shing stress eoming serious (Fig. 4A). F m is fluoresene yiel when PSII retion enter is totlly lose, refleting stte of eletril trnsfer when psse PSII (Rzvi et l., 28). From 79 Fig. 3B, it n e seen tht uner the sme light, with the stress time inrese, F m expresse eline teneny. After 6 ys, the erese of F m vries in ifferent situtions, with 35.44% uner mil stress, 39.24% uner moerte stress, 48.% uner severe stress. Although mge for these stresses oul reover fter the light ws reovere, there were signifint ifferenes on mge reover etween in severe shing stress group n ontrol group (p<.5). Others oul e le to reover the norml level n there were no signifint ifferenes etween them (p<.5) (Fig. 4B). F v /F m is the mximl photohemil yiel of PSII, refleting the light energy trnsformtion effiieny of PSII. From Fig. 4C, it n e seen tht Fv/Fm of strwerry kept.8 on verge n there ws no signifint ifferene mong them when given norml light. However, F v /F m grully eline with shing stress inrese in the sitution of the sme time. Uner the sme shing stress, F v /F m lso grully eline with shing stress time inrese. But F v /F m h

5 Av. J. Foo Si. Tehnol., 5(6): , 23.3 A B.9 C F.5 F m.6 F v /F m Time () Time () Time ().8.6 D.8 E.8 CK T T2 T3 F Yiel.4 qp.6.4 qn Time () Time () Time () Fig. 4: The hnge of hlorophyll fluoresene prmeters in lef of F. nnss uner shing stress expresse signifint erese ompre with the ontrol group. The eline of F v /F m vries in ifferent sitution, with 5.38% uner mil stress, 28.2% uner moerte stress, 58.97% uner severe stress. Fv/Fm hs inrese fter the light ws reovere. However, F v /F m uner severe stress only reovere its 6.2% of the ontrol group n there were signifint ifferenes on mge reover etween in severe shing stress group n ontrol group (p<.5). Others oul e le to reover the norml level n there were no signifint ifferenes etween them (p>.5) (Fig. 3C). A numer of reserhes stte tht there is positive orreltion etween F v /F m n plnts growth onition (Rzvi et l., 28)). When plnt is in norml onition, the F v /F m hs slight hnge n vries from.75 to.85. F v /F m hs signifint eline when plnt is in stress onition, whih shows tht the erese of photohemil effiieny hs seriously limite the norml photosynthesis of strwerry. Comine with the experiment result of F uner shing stress, it showe tht shing stress h prtil mge on primry retion proess of strwerry photosynthesis. Yiel is the effetive quntum output of PSII, refleting the tul light energy rresting effiieny of PSII, when prt of PSII retion is lose. It n e iretly teste when lef oes not put in pttion to rkness n s n inex of plnt photosynthesis 79 eletril trnsport rte. From Fig. 4D, it n e seen tht with stress time inrese, yiel grully eline. At the primry shing stge, yiel hs slowly eline. After 6 ys, it expresse signifint erese ompre with ontrol group (p<.5). The eline of yiel vries in ifferent situtions, with 36.76% uner mil stress, 44.2% uner moerte stress, 83.82% uner severe stress. Although yiel hs reover fter the light ws reovere, yiel uner severe stress only reovere its 32.8% of the ontrol group. There were signifint ifferenes on mge reover etween in severe shing stress group n ontrol group (p<.5). Others oul e le to reover the norml level n there were no signifint ifferenes etween them (p>.5) (Fig. 3D). From Fig. 4E, it n e seen tht with the sme time, qp grully eline with stress time inrese. At the primry shing stge, qp hs slowly eline. After 6 ys, it expresse signifint erese, ompre with ontrol group (p<.5). The eline of qp vries in ifferent situtions, with 23.66% uner mil stress, 39.78% uner moerte stress, 9.39% uner severe stress. Although qp hs reover fter the light ws reovere, qp uner severe stress only reovere its 49.43% of the ontrol group. There were signifint ifferenes on mge reover etween in severe shing stress group n ontrol group (p<.5).

6 Others oul e le to reover the norml level n there were no signifint ifferenes etween them (p>.5) (Fig. 3E). Miyke et l. (25) suggeste tht the inrese of qn inue y non-ritive issiption ws photoprotetive proess. From Fig. 4F, it n e seen tht qn grully rise with stress time inrese. After 6 ys, it expresse signifint inresent ompre with ontrol group (p<.5). Compre with the originl vlue, the inresent of qn vries in ifferent situtions, with 7.25 times uner mil stress, times uner moerte stress, 46 times uner severe stress. Although qn hs reovere fter the light ws reovere, qn uner severe stress is out 4 times s gret s the ontrol group. There were signifint ifferenes on mge reover etween in severe shing stress group n ontrol group (p<.5). Others oul e le to reover the norml level n there were no signifint ifferenes etween them (p>.5) (Fig. 3F). CONCLUSION Beuse of the shing reues the light intensity, the net photosyntheti rte per unit re eline gretly, n the gretest net photosyntheti rte n totl photosyntheti umultion in y erese. At the sme time, shing wekens the CO 2 fixtion pility, whih we n see from the Croxyltion Effiieny (CE) erese. So when we pln strwerry in the glsshouse, we hve to onsier not only the epenene light, ut lso the epenene CO 2. Applition of CO 2 fertilizer will enefit strwerry photosyntheti umultion n growth. Tht first shing stress then light reovery n reflet the ility tht plnt pts to shing stress n its protetion mehnism. After 7 ys, the hlorophyll fluoresene prmeters (F o, F m, F v /F m, Yiel, qp, qn) n reover silly its innte level when strwerry is uner mil stress or moerte stress. However, there were signifint ifferenes on mge reover etween in severe shing stress group n ontrol group (p<.5). All these stte tht the mge of PSII retion enter n reover its norml level, when the environment is goo. But the lef suffer severe mge, it is hrly to reovery. Thus, it is neessry to py ttention to ontrol light when plnte strwerry n often keep soil wet. Besies, for those strwerries whih sty in shing onition for long time, it is vitl to supply light to voi strwerry keeping in serious shing stress. ACKNOWLEDGMENT We woul lso like to thnk the memers of the eology Reserh Institute of Shnxi norml university. This stuy ws jointly fune y the Ntionl Nturl Siene Fountion of Chin (NSFC 33), the exellent provinil young fun of Anhui (22SQRL3ZD) n the otor fun of Anqing Tehers College. Av. J. Foo Si. Tehnol., 5(6): , REFERENCES Chzon, R.L., 992. Photosyntheti plstiity of two rin-forest shrus ross nturl gp trnsets. Oeologi, 92: Delgrnge, S., 2. Light-n sesonl-inue plstiity in lef morphology, N prtitioning n photosyntheti pity of two temperte eiuous speies. Environ. Exp. Botny, 7: -. Feijó, N.S.A., M.S. Mielke, F.P. Gomes, S. Frn n A.O. Lvinsky, 29. Growth n photosyntheti responses of Gllesi integrifoli (Spreng.) Hrms n Shinus tereinthifolius Ri seelings in ense she. Agroforest. Syst., 77: Ginoli, E. n F. Vllres, 22. Stuying phenotypi plstiity: The vntges of ro pproh. Biol. J. Linnen So., 5: -7. Jensen, A.M., E.S. Griner n K.C. Vughn, 22. High-light limtion in Querus rour L. seelings upon over-topping she environment. Environ. Exp. Botny, 78: Miyke, C., S. Horiguhi, A. Mkino, Y. Shinzki, H. Ymmoto n K. Tomizw, 25. Effets of light intensity on yli eletron flow roun PSI n its reltionship to non-photohemil quenhing of hl fluoresene in too leves. Plnt Cell Physiol., 46: Oguhi, R., K. Hikosk, T. Hiur n T. Hirose, 26. Lef ntomy n light limtion in wooy seelings fter gp formtion in ool-temperte eiuous forest. Oeologi, 49: Rzvi, F., B. Pollet, K. Steppe n M.C. Vnleke, 28. Chlorophyll fluoresene s tool for evlution of rought stress in strwerry. Photosyntheti, 46(4): Shimtni, I.K. n Y. Kuot, 2. The sptiotemporl forest pth ynmis inferre from the fine-sle synhroniity in growth hronology. J. Vegett. Si., 22: Vllres, F. n R.W. Pery, 998. The funtionl eology of shoot rhiteture in sun n she plnts of Heteromeles rutifoli M. Roem, Clifornin hprrl shru. Oeologi, 4: -. Vn Kleunen, M. n M. Fisher, 25. Constrints on the evolution of ptive phenotypi plstiity in plnts. New Phytol., 66: Wng, L.J., W.B. Jing n B.J. Hung, 24. Promotion of 5- minole-vulini i on photosynthesis of melon (Cuumis melo L.) seelings uner lowlight n hilling stress grown onitions. Plnt Physiol., 2(2): Wyk, T.P., J. Oleksyn, R. Zytkowik, P. Krolewski, A.M. Jgozinski n P.B. Reih, 22. Responses of lef struture n photosyntheti properties to intr-nopy light grients: A ommon gren test with four rolef eiuous ngiosperm n seven evergreen onifer tree speies. Oeologi, 7: -24.