Chlorophyll Fluorescence and Flowering Behaviour of Annual-Fruiting Raspberry

Transcription

1 Chlorophyll Fluorescence nd Flowering Behviour of Annul-Fruiting Rsperry Cultivrs under Elevted Temperture Regimes T.P. Gotme 1), L. Andersen 1), K.K. Petersen 1), H.L. Pedersen 2), C.O. Ottosen 1) nd J. Grhm 3) ( 1) Deprtment of Food Science, Arhus University, Denmrk; 2) GrtneriRådgivningen A/S, HortiAdvice Scndinvi, Denmrk nd 3) The Jmes Hutton Institute, Scotlnd, UK) 6 7 Summry The effects of seven dy period with incresed temperture from stndrd level of 20 C to 27, 32 or 37 C during flower initition on pprent quntum efficiency (F v /F m ), chlorophyll content nd flowering ehviour in rsperry Autumn Bliss, Autumn Tresure, Erik, Fll Gold nd Polk were investigted. The F v /F m decresed stedily from 0.82 to 0.70 on the seventh dy t 37 C in Autumn Bliss nd Fll Gold. A significnt diurnl vrition in F v /F m, chrcterized y middy depression nd prtil recovery in the evening ws oserved in Polk. Plnts of Autumn Bliss exposed for seven dys to 37 C hd 58% less chlorophyll s compred to those grown t 20 C. The chlorophyll / rtio decresed to 20% t 37 C in Autumn Bliss, nd Fll Gold. The numer of dys to nthesis of the terminl flower ws not significntly ffected y the temperture tretments. The numer of unopened xillry uds decresed t 37 C in Autumn Bliss, Autumn Tresure, Fll Gold nd Polk. The percentge of flowering lterl shoots per plnt decresed y 16% t 37 C in Autumn Bliss wheres it incresed y 7% t 37 C in Autumn Tresure nd Erik. The percentge of flower uds per plnt decresed y 20% t 37 C in Autumn Tresure nd Erik. Thus the negtive responses of het stress cross the temperture regimes ws reflected in F v /F m in ll cultivrs, while there ws remrkle difference in chlorophyll content nd flowering ehviour mong cultivrs. These responses suggest tht there is 1

2 potentil difference of nnul-fruiting rsperry cultivrs in their inherent ility to dpt to het stress, which ws reflected in photosynthetic pigments nd susequent flowering ehviour. Key words. chlorophyll content photosynthesis - Ruus ideus - het stress - terminl flower Introduction Rsperry (Ruus ideus L.) is n importnt soft fruit crop cross cold nd temperte regions of the world (HEIDE nd SONSTEBY 2011; SONSTEBY nd HEIDE 2012) nd interest in rsperry production under open-field, high-tunnel nd greenhouse conditions hs een incresing (OLIVEIRA et l. 2002; DALE et l. 2003; DALE et l. 2005). Mnipultion of the growth cycle in nnul-fruiting rsperry cultivrs llows yer-round production of fruit in the greenhouse (DALE et l. 2005). However, the effect of temperture on flower formtion in nnul-fruiting cultivrs is eing discussed (HEIDE nd SONSTEBY 2011). The optimum temperture for nnul-fruiting rsperry cultivtion rnges from 16 to 24 C, ut some cultivrs like Polk grow well even t 30 C (HEIDE nd SONSTEBY 2011). In nnul-fruiting rsperries, the environmentl regultion of flower induction is not fully understood (CAREW et l. 2001; SONSTEBY nd HEIDE 2010). But flowering is dvnced y intermedite photoperiods (11-15 h) nd tempertures etween 20 nd 25 C (CAREW et l. 2001; SONSTEBY nd HEIDE 2010; NERI et l. 2012). Most rsperry cultivrs re poorly dpted to wrm nd humid conditions tht my occur during summer (BALLINGTON nd FERNANDEZ 2008). Tempertures ove optimum negtively ffects plnt growth in ll developmentl stges from shoot formtion in the spring to flowering nd fruit ripening. However, the upper temperture threshold for optiml growth vries significntly t different phenologicl nd 2

3 growth stges. Excessively high temperture (10-15 C ove optimum) dversely ffects photosynthesis, respirtion, evpotrnspirtion, memrne integrity nd modultes hormone nd metolite production (WAHID et l. 2007). Photosynthesis is one of the most hetsensitive processes in plnts (BERRY nd BJORKMAN 1980; WASID et l. 2007) nd mny uthors hve shown tht elevted temperture reduces net ssimiltion due to impirment of CO 2 fixtion, photophosphoryltion nd the electron trnsport chin (SALVUCCI nd CRAFTS- BRANDNER 2004; SALVUCCI nd CRAFTS-BRANDNER 2004). Furthermore, high temperture decreses photosynthetic efficiency, chlorophyll ccumultion nd regultes het shock proteins (EFEOGLU nd TERZIOGLU 2009). MOLINA-BRAVO et l. (2011) reported lower rtio of vrile to mximum chlorophyll fluorescence (F v /F m ) in het sensitive rsperry cultivrs with the lowest vlues in the fternoon. Moreover, het stress my decrese the totl concentrtion of chlorophyll pigments, chnge the rtio of chlorophyll to (Chl /), nd chlorophyll to crotenoid content (+/x+c) in stressed leves depending on the temperture tolernce of the species (CAMEJO et l. 2005; EFEOGLU nd TERZIOGLU 2009). An incresing interest in producing rsperries in wrmer climtes nd out-of-seson in protected cultivtion hs stimulted reserch imed t etter understnding of the effects of temperture nd photoperiod on growth nd fruiting (CAREW et l. 2000; CAREW et l. 2001; DALE et l. 2003; SONSTEBY nd HEIDE 2010). In this study, the effects of high temperture during erly flower initition on flowering ehviour of five nnul-fruiting rsperry cultivrs were investigted to pin point possile control mechnisms underlying the differences etween cultivrs. The im of the study ws lso to determine if chlorophyll fluorescence my e used s screening criterion for high-temperture sensitivity in nnulfruiting rsperry cultivrs Mterils nd Methods 3

4 Plnt mteril nd experimentl conditions One-yer old cold-stored plnts of five nnul-fruiting rsperry cultivrs; Autumn Bliss, Autumn Tresure, Fll Gold, Erik nd Polk were otined from the nursery Vester Skovgrd, Denmrk, where they were lifted from the field in mid-novemer 2010 nd kept in drk cold-store t 2 C efore shipping to the Deprtment of Food Science, Arhus University on 20 Jnury The plnts were stored on site in drk cold room (2 ±1 C) for dditionl 9, 10 or 11 weeks, which resulted in cold-storge for totl of 15, 16 or 17 weeks efore forcing under greenhouse conditions. The cnes were pruned to soil level nd potted in 3.5 L pots contining mm londe pet sustrte (Pindstrup No 4, Pindstrup Moserug A/S, Ryomgrd, Denmrk), with n electricl conductivity (EC) of 2-4 (ms cm -1 ) nd ph 6. Plnts were forced t C nd photoperiod of 14 h until flower initition. Microscopic oservtion of xillry uds from non-experimentl plnts ws crried out five weeks fter root sprouting to determine the time of flower initition. Flower primordi were visile under the microscope fter seven weeks (WILLIAMS 1959). A single primry shoot ws mintined per pot during the experimentl period. Plnts were fertigted once dy to pot cpcity using nutrient solution with n EC of 2.16 ms cm -1 contining 40 mg L -1 NH 4 -N, 165 mg L -1 NO 3 -N, 44 mg L -1 P nd 257 mg L -1 K Het stress tretments When plnts reched the stge of flower initition (~ seven weeks fter root sprouting), they were trnsferred to three climte chmers (MB-teknik, Broendy, Denmrk) t 27, 32 or 37 C, with dy length of 14 h similr to the greenhouse. There were three plnts per cultivr, tretment nd cold-storge time (15, 16 nd 17 weeks). The temperture tretment ws given for seven dy (~168 h) period. A fourth set of plnts remined in the greenhouse t temperture rnging from 20 to 25 C nd 14 h light conditions s reference. In the climte 4

5 chmers, the irrdince ws constnt t 350 µmol m -2 s -1 PAR nd RH ws 60% ±5% for ll replictions. All plnts were fertigted with complete nutrient solution to pot cpcity t m nd pm Mesurement of chlorophyll fluorescence During the seven dys of het tretment, chlorophyll fluorescence ws mesured on the third lef ( 75% expnded) from the top of the shoot etween m to pm ech dy to minimize the diurnl effects of temperture nd light on photosynthesis. A pulse-mplitude modulted fluorometer (MiniPm; Heinz Wlz GmH, Eiffeltrich, Germny) ws used on the upper surfce fter 30-min drk dpttion using stndrd lef clip. Initil fluorescence (F o ), when plstoquinine electron cceptor pool (Q A ) is fully oxidized nd mximum fluorescence (F m ), when Q A is trnsiently fully reduced, were recorded for photosystem II nd vrile fluorescence (F v = F m F o ) nd mximum quntum efficiency (F v /F m ) were clculted. The F v /F m redings were tken on the third lef (~75% expnded) from the top of the shoot in Polk etween nd m, m nd pm, nd nd pm to descrie diurnl vritions in pprent quntum efficiency Chlorophyll pigment At the end of the het stress tretment, hlf of ech lef used to mesure F v /F m ws collected nd weighed nd immeditely frozen in liquid nitrogen nd stored t -80 C. The smples were freeze-dried for 48 h nd homogenised into fine powder. Approx. five mg of the homogenised freeze-dried tissue ws weighed in 15 ml test-tue nd 100 μl distilled wter ws dded. After 10 min of hydrtion, 8 ml of 96% ethnol ws dded efore shking in vortex t pprox. 250 rpm for min. The smples were wrpped in luminium foil nd incuted t room temperture in n exhust hood overnight. Smples were vortexed for one 5

6 min nd the sornce ws mesured on the superntnt t 470.0, 648.6, nd 750 nm using spectrophotometer (UV-1700, Shimdzu, Jpn). The chlorophyll, chlorophyll, chlorophyll / nd the rtio of chlorophyll (+) to crotenoid (x+c) were clculted s descried y LICHTENTHALER (1987) Plnt growth nd flowering ehviour After the seven dy tretment t elevted temperture regimes in climte chmers, plnts were trnsferred to n open high tunnel (Atopln Longlife film, Vorden, The Netherlnds), nd the third node from top of the shoot ws mrked to indicte new shoot nd lef development fter stress tretment. The plnts were plced in rows on ground cover with lck Mypex with n inter-row spcing of 1 m nd 0.30 m etween plnts. Plnts were dripirrigted with complete nutrient solution. For ech plnt, the dy of nthesis of the terminl flower ws recorded nd plnt growth nd flowering ehviour were evluted 30 dys fter nthesis of the terminl flower. Dys to nthesis of the terminl flower ws counted from the dy of root sprouting when forcing them in greenhouse. The following were recorded: lef re (LI-3100 Lef Are Meter, LI-COR, Lincoln, USA) of leves developed ove the mrked node, totl numer of lterl shoots, numer of flowering lterl shoots nd numer of unopened xillry uds. The percentge of unopened flower uds ws clculted s: Unopened flower uds (%) = (Unopened flower uds)*100/ (Unopened flower uds + flowers nd fruit) Experimentl design nd sttisticl nlysis The experiment ws split plot design with three cold-storge durtion s min-plot nd temperture s su-plot. Repeted (F v /F m ) mesurements were conducted every dy during the seven dy temperture tretment. Sttisticl nlysis ws crried out using the SAS procedure 6

7 PROC MIXED (SAS Inst. Inc., Cry, NC). Ech cultivr ws nlysed seprtely. Dt were tested for norml distriution nd homogeneity of vrince efore nlysis. The percentge nd proportionl dt were rcsine trnsformed prior to sttisticl nlysis, originl men vlues re shown in figures nd tles. Men differences within cultivr, temperture nd cold storge durtion were seprted using Tukey Krmer s test t P Results Chlorophyll fluorescence Three-wy interction etween cold-storge durtion, temperture nd dys of temperture stress ws found for ll cultivrs (Tle 1 nd Fig. 1). The F v /F m decresed with incresed stress period t 27, 32 nd 37 C nd the highest reduction ws from 0.82 to 0.70 t 37 ºC t dy seven in Autumn Bliss nd Fll Gold. While in Autumn Tresure nd Erik, the F v /F m ws reduced to 0.72 t dy seven t 37 C. A similr pttern for F v /F m during the period of incresed temperture ws found for plnts cold-stored for 15 nd 16 weeks ut for plnts cold stored for 17 weeks, F v /F m dropped more quickly etween dys one nd five. There ws n rupt drop in F v /F m t 32 nd 37 C in ll cultivrs until dy five of stress tretment Diurnl vritions in F v /F m in Polk Similr to the other four cultivrs, middy F v /F m in Polk decresed from 0.82 to 0.71 t the end of the seven dy stress period (Fig. 2). However, the F v /F m rtio remined constntly higher in the morning nd evening s compred with middy (P<0.001). When sttisticl nlysis ws crried out using cold-storge durtion (C), temperture (T), dys of temperture stress (S), nd time of dy (D) s clss vriles, the four-wy (C*T*S*D) nd three-wy 7

8 (C*T*D) interctions were not significnt while C*T*S nd T*S*D were significnt for F v /F m (P<0.05) Chlorophyll pigments The effect of temperture on chlorophyll pigments vried with cultivr. The Chl nd Chl / significntly decresed with incresing temperture in Autumn Bliss, Fll Gold nd Polk, while there ws no effect in Autumn Tresure nd Erik (Fig. 3A). The decrese in Chl t 37 C rnged from 20 to 58% in Autumn Bliss nd Fll Gold, respectively, when compred with greenhouse conditions nd resulted in yellowing of the upper leves. Similrly, Chl / decresed from 5 to 20% in Autumn Bliss, Fll Gold nd Polk t 37 C (Fig. 3B). The chlorophyll to crotenoid (+)/(x+c) rtio significntly decresed in Erik, with incresed temperture (Fig. 3C). Therefore Autumn Tresure nd Erik could not e regrded s het sensitive ccording to these prmeters Growth nd flowering The lef re of the min shoot developed etween seven dy period t 37 C nd 30 dys fter nthesis of the terminl flower ws significntly lower (P<0.05) in Autumn Tresure, Erik, Fll Gold, nd Polk nd the reduction rnged from 68 to 82% compred with reference plnts grown in greenhouse. The numer of unopened xillry uds t the min shoot decresed significntly fter seven dys t 37 C in Autumn Bliss, Autumn Tresure, Fll Gold nd Polk wheres the numer of lterl shoots per plnt ws incresed in Autumn Bliss (175%), Erik (66%) nd Fll Gold (31%) compred with greenhouse conditions (Tle 2). The percentge of flowering lterl shoots per plnt decresed y 16% in Autumn Bliss fter exposure to 37 C ut other cultivrs were not ffected y the temperture tretments. The height of the min shoot following seven dy stress period t 8

9 C ws significntly reduced in Autumn Tresure, Erik nd Polk. The numer of dys to nthesis of the terminl flower ws not influenced y incresed temperture in ny of the five cultivrs (Fig. 4) ut the percentge of unopened flower uds ws decresed up to 22% in Autumn Tresure nd Erik y seven dy period t 37 C compred to greenhouse conditions. However, the numer of ripe fruits t 30 dys fter nthesis of the terminl flower ws not ffected y incresed tempertures during flower initition (dt not shown). The effect of cold-storge durtion on growth nd flowering ehviour is presented in tle 3. The lef re of the min shoot developed fter het stress period incresed significntly on Autumn Bliss nd Erik. The numer of unopened xillry uds, numer of lterl shoots per plnt, numer of flower nd uds per lterl nd min shoot height were influenced y longer cold-storge durtion in Autumn Bliss nd Fll Gold. The numer of flowers nd unopened uds per lterl ws 43 in Autumn Bliss nd 36 in Fll Gold t longer period of cold-storge period (17 weeks). However, other cultivrs were not significntly ffected y cold-storge period Discussion Chlorophyll fluorescence The effect of extreme tempertures on plnt growth, development nd reproductive ehviour is complex due to the comined effect of environment nd genetic fctors. The dmge cused y high tempertures includes wide rnge of structurl nd functionl chnges in plnts (GEORGIEVA et l. 2000). At tempertures ove the optimum, the pprent quntum yield declines due to inhiition of PSII ctivity (BERRY et l. 1980). The het stress hs 9

10 direct effect on the PSII photo-oxidizing site nd decreses the emission of the vrile chlorophyll fluorescence (GEORGIEVA et l. 2000). The drk-dpted vlue of F v /F m is therefore sensitive indictor of mximl photosynthetic performnce with optiml vlues round 0.83 for most plnt species (BJORKMAN nd DEMMING 1987). In our oservtions, F v /F m decresed stedily from 0.82 to 0.70 t 37 C fter 168 h of exposure. This decrese in F v /F m ws only wek nd recoverle effect nd therefore not likely to hve ny mjor impct on the D1 protein repir system (LEIPNER 2007). In our experiment, F v /F m for Polk ws lwys higher in the morning nd evening thn t middy regrdless of temperture tretment nd period of cold-storge. The middy F v /F m decresed with incresed stress period nd temperture (P<0.001). The depression t middy nd the prtil recovery in the evening indicted tht photoinhiition ws reversile in Polk. Moreover, it ws oserved tht F v /F m did not fully recover in the morning fter consecutive stress periods thus the repir mechnism ws not sufficient. The diurnl chnges; the highest Fv/Fm in the morning, minimum t noon nd grdully recovered in lte fternoon ws oserved in soyen plnts (KAO nd FORSETH 1992). In contrst to our results, the highest effect of het stress ws oserved in the fternoon of het susceptile rsperry cultivrs (MOLINA-BRAVO et l. 2011). The significntly stronger depression of F v /F m in plnts cold-stored for 17 weeks, s compred to 15 nd 16 weeks, my imply the opertion of quntittive chilling effect, ut this could not e vlidted y the present study. The F v /F m mesurement indictes tht ll five cultivrs hve n lmost similr response with regrd to het tolernce Chlorophyll pigments Elevted temperture regimes ffect the totl concentrtion of chlorophyll pigments in leves depending on the thermotolernce cpcity of the species (CAMEJO et l. 2005; GUO et l. 2006; EFEOGLU nd TERZIOGLU 2009). The Chl / rtio is n indictor of the functionl 10

11 pigment equipment nd light dpttion/cclimtion cpcity of the photosynthetic pprtus. Chl is found exclusively in the pigment ntenn system, wheres Chl is present in the rection centres of PSI nd PSII s well s in the pigment ntenn (GUO et l. 2006). We oserved tht the Chl nd Chl / decresed significntly t high temperture in Autumn Bliss nd Fll Gold compred to greenhouse conditions. The low Chl / suggests decrese in the rtio of rection centres compred to light hrvesting proteins while the lower Chl content suggests decrese in light hrvesting cpcity (ADAMS nd BARKER 1998). The chlorophyll concentrtion decresed in Sutsum mndrin, when the temperture ws incresed to 38 C for 15-dys stress period (GUO et l. 2006). The mesured level of Chl nd Chl / indicte tht Autumn Bliss nd Fll Gold re less het tolernt while Autumn Tresure nd Erik were not het sensitive ccording to these prmeters Growth nd flowering Due to their temperte origin, the plsticity of current rsperry cultivrs to dpt to high temperture is limited (BALLINGTON nd FERNANDEZ 2008). Incresed temperture up to 24 C dvnced nthesis nd incresed numer of leves in Autumn Bliss (CAREW et l. 2003; HEIDE nd SONSTEBY 2011). In our study, the opening dte of the terminl flower ws not significntly ffected y het stress during flower initition, presumly ecuse stress ws imposed for short period. However, t high temperture (37 C), nthesis of the terminl flower in Autumn Bliss, Fll Gold nd Polk tended to e dvnced, while in Autumn Tresure nd Erik, it tended to e delyed. SONSTEBY nd HEIDE (2010) oserved tht flowering nd fruit mturtion ws dvnced y elevted temperture from 20 to 26 C in Autumn Bliss ut delyed in Autumn Tresure ove 20 C. There were higher numer of lterl shoots in Autumn Bliss in the shorter cold-storge period. The result is surprising ecuse the chilling periods used were very much longer (>15 weeks) thn 11

12 those suggested y other workers to stisfy the chilling requirement (TAKEDA 1993; CAREW et l. 2001). Chilling is not n solute requirement of nnul-fruiting rsperries ut cold tretment dvnces the dy-to-flower opening in mny nnul cultivrs (TAKEDA 1993; HEIDE nd SONSTEBY 2011). Others reported tht flowering ws dvnced when chilling durtion incresed from 0 to 10 weeks in Autumn Bliss (CAREW et l. 2001). As chilling durtion incresed, the rte of vegettive growth incresed nd dys-to-first flower opening decresed in Autumn Bliss. Similrly, cold tretment ffected flower ud development. For exmple, non-chilled Heritge plnts developed 15 flowering lterl shoots, while plnts receiving >750 chilling units hd 25 flowering lterl shoots (TAKEDA 1993). Therefore low temperture exposure lso known s vernliztion prior to shoot growth is needed for flower ud initition (TAKEDA 1993; HEIDE nd SONSTEBY 2011). Our results re in greement with CAREW et l. (2001), who reported tht cold-storge influences vegettive nd flowering ehviour of rsperry cultivrs. The differences could lso e due to the loss of crohydrtes during cold-storge nd differences in climte conditions in the greenhouse, lthough the temperture ws mintined similr for ech repliction, while light nd RH oviously were not fully controlled in greenhouse s compred to climte chmers Conclusion Short exposure of nnul-fruiting rsperry cultivrs to high temperture decreses middy F v /F m nd chlorophyll content. A decline in the efficcy of photosystem II under elevted temperture regimes t middy nd prtil recovery t evening in Polk my indicte coordinted chnges in the photosynthetic pprtus nd processing tht might help plnts to survive in het stress. The results suggest tht het tolernce of nnul-fruiting rsperry grown in wrm regions could e improved y selecting cultivrs with high photochemicl ctivity s mnifested y high pprent quntum efficiency (F v /F m ). Furthermore, s chilling 12

13 increses, in our cse cold-store durtion, the rte of vegettive growth increses in Autumn Bliss nd Fll Gold. Moreover, het stress enhnces erlier flowering in Autumn Bliss nd delyed in Autumn Tresure, indicting distinct cultivr differences. In commercil production, this informtion my e useful for mnipulting nd optimizing fruit production in glsshouses nd outside in wrmer regions. Therefore evlution of rsperry germplsm for cultivtion in wrmer res should e performed. However, we suggest tht longer exposure thn the seven dy period nd ove 37 C should lso e exmined to understnd the effects of het stress in detil Acknowledgements We grtefully cknowledge the finncil support from Interreg IVB North Se Region, EU Progrmme Project ID: (ClimFruit) to crry out this experiment References ADAMS, W.W.I. nd D.H. BARKER 1998: Sesonl chnges in xnthophyll cycle-dependent energy dissiption in Yucc gluc Nuttll. Plnt Cell Environ. 21, BALLINGTON, J.R. nd G.E. FERNANDEZ 2008: Breeding rsperries dpted to wrm humid climte with fluctuting temperture in winter. Act Hort. 777, BERRY, J. nd O. BJORKMAN 1980: Photosynthetic response nd dpttion to temperture in higher plnts. Annu. Rev. Plnt Physiol. 31, BJORKMAN, O. nd B. DEMMING 1987: Photon yield of O 2 evolution nd chlorophyll fluorescence chrcteristics t 77 K mong vsculr plnts of diverse origins. Plnt 170,

14 CAMEJO, D., P. RODRIGUEZ, A. MORALES, J.M. DELL'AMICO, A. TORRECILLAS nd J.J. ALARCON 2005: High temperture effects on photosynthetic ctivity of two tomto cultivrs with different het susceptiility. Plnt Physiol. 162, CAREW, J.G., T. GILLESPIE, J. WHITE, H. WAINWRIGHT, R. BRENNAN nd N.H. BATTEY 2000: The control of the nnul growth cycle in rsperry. J. Hort. Sci. Biotechnol. 75, CAREW, J.G., K. MAHMOOD, J. DARBY, P. HADLEY nd N.H. BATTEY 2001: The effect of low temperture on the vegettive growth nd flowering of the primocne fruiting rsperry 'Autumn Bliss'. J. Hort. Sci. Biotecnol. 76, CAREW, J.G., K. MAHMOOD, J. DARBY, P. HADLEY nd N.H. BATTEY 2003: The effect of temperture, photosynthetic photon flux density, nd photoperiod on the vegettive growth nd flowering of 'Autumn Bliss' rsperry. J. Am. Soc. Hort. Sci. 128, DALE, A., S. PIRGOZLIEV, E.M. KING nd A. SAMPLE 2005: Scheduling primocne-fruiting rsperries (Ruus ideus L.) for yer-round production in greenhouses y chilling nd Summer-pruning of cnes. J. Hort. Sci. Biotechnol. 80, DALE, A., A. SAMPLE nd E. KING 2003: Breking dormncy in red rsperries for greenhouse production. HortScience 38, EFEOGLU, B. nd S. TERZIOGLU 2009: Photosynthetic response of two whet vrieties to high temperture. EurAsi J. Biosci. 3, GEORGIEVA, K., T.TSONEV, V. VELIKOVA. nd I YORDANOV 2000: Photosynthetic ctivity during high temperture tretment of pe plnts. J. Plnt Physiol. 157, GUO, Y.P., H.F. ZHOU nd L.C. ZHANG 2006: Photosynthetic chrcteristics nd protective mechnisms ginst photooxidtion during high temperture stress in two citrus species. Scienti Horticulture 108, GULEN, H. nd A. ERIS 2004: Effect of het stress on peroxidse ctivity nd totl protein content in strwerry plnts. Plnt Science 166,

15 HEIDE, O.M. nd A. SONSTEBY 2011: Physiology of flowering nd dormncy regultion in nnul nd iennil-fruiting red rsperry (Ruus ideus L.) - review. J. Hort. Sci. Biotechnol. 86, KADIR, S., M. VON WEIHE nd K. AL-KHATIB 2007: Photochemicl efficiency nd recovery of photosystem II in grpes fter exposure to sudden nd grdul het stress. J. Am. Soc. Hort. Sci. 132, KAO, W.K. nd I. N. FORSETH Diurnl lef movement, chlorophyll fluorescence nd cron ssimilltion in soyen grown under different nitrogen nd wter vililities. Plnt Cell Environ. 15, LEIPNER, J. 2007: Chlorophyll fluorescence mesurement in plnt iology. Swiss Federl Institute of Technology, Zurich. Aville t (ccessed: ). LICHTENTHALER, H.K. 1987: Chlrophyll nd crotenoids pigments of photosynthetic iomemrnes. Methods Enzymol. 148: MOLINA-BRAVO, R., C. ARELLANO, B.R. SOSINSKI nd G.E. FERNANDEZ 2011: A protocol to ssess het tolernce in segregting popultion of rsperry using chlorophyll fluorescence. Scienti Horticulture 130, NERI, D., F. MASSETANI, P. ZUCCHI, M. GIACOMELLI nd G. SAVINI 2012: Flower differentition nd plnt rchitecture of rsperry, lckerry nd white- nd redcurrnt. Act Hort. 926, OLIVEIRA, P.B., L. LOPES-DA-FONSECA nd A.A. MONTEIRO 2002: Comining different growing techniques for ll yer round red rsperry production in Portugl. Proc. Eighth Intern. Ruus nd Ries Symp, 1 nd 2,

16 PAGTER, M., F.L. LIU, C.R JENSEN nd K.K. PETERSEN 2008: Effects of chilling tempertures nd short photoperiod on PSII function, sugr concentrtions nd xylem sp ABA concentrtions in two Hydrnge species. Plnt Sci. 175, SALVUCCI, M.E. nd S.J. CRAFTS-BRANDNER 2004: Inhiition of photosynthesis y het stress: the ctivtion stte of ruisco s limiting fctor in photosynthesis. Physiol. Plntrum 120, SALVUCCI, M.E. nd S.J. CRAFTS-BRANDNER 2004: Reltionship etween the het tolernce of photosynthesis nd the therml stility of ruisco ctivse in plnts from contrsting therml environments. Plnt Physiol. 134, SCHREIBER, U. nd J.A. BERRY 1977: Het-induced chnges of chlorophyll fluorescence in intct leves correlted with dmge of photosynthetic pprtus. Plnt 136, SONSTEBY, A. nd O.M. HEIDE 2009: Effects of photoperiod nd temperture on growth nd flowering in the nnul (primocne) fruiting rsperry (Ruus ideus L.) cultivr 'Polk'. J. Hort. Sci. Biotechnol. 84, SONSTEBY, A. nd O.M. HEIDE 2010: Erliness nd fruit yield nd qulity of nnul-fruiting red rsperry (Ruus ideus L.): Effects of temperture nd genotype. J. Hort. Sci. Biotechnol. 85, SONSTEBY, A. nd O.M. HEIDE 2012: Effect of photoperiod nd temperture on growth, flowering nd fruit yield in nnul-fruiting red rsperry cultivrs (Ruus ideus L.). Europ. J. Hort. Sci. 77 (3), STAFNE, E.T., J.R. CLARK nd C.R. ROM 2000: Lef gs exchnge chrcteristics of red rsperry germplsm in hot environment. HortScience 35, STAFNE, E.T., J.R. CLARK nd C.R. ROM 2001: Lef gs exchnge response of 'Arpho' lckerry nd six red rsperry cultivrs to moderte nd high tempertures. HortScience 36,

17 TAKEDA, F. 1993: Chilling ffects flowering of primocne fruiting 'Heritge' rsperry. Act Hort. 352, WAHID, A., S. GELANI, M. ASHRAF nd M.R. FOOLAD 2007: Het tolernce in plnts: An overview. Environ. Exp. Bot. 61, WILLIAMS, I. H. 1959: Effect of environment on Ruus ideus L. IV. Flower initition nd development of the inflorescence. J. Hort. Sci. 34, Address of Authors: Tek Prsd Gotme (corresponding uthor), Lillie Andersen, Kren Koefoed Petersen, Crl-Otto Ottosen, Deprtment of Food Science, Arhus University, Kirstinejergvej 10, DK-5792, Arslev, Denmrk; Hnne Lindhrd Pedersen, GrtneriRådgivningen A/S - HortiAdvice Scndinvi A/S - Hvidkærvej 29 - DK-5250, Denmrk nd Julie Grhm, The Jmes Hutton Institute, Invergowrie, Dundee DD2 5DA, Scotlnd, UK, emil (corresponding uthor): tek.gotme@grsci.dk 17

18 Figure Cptions Fig. 1. The effect of het stress tretment (dys) nd preceding cold-storge durtion (15, 16 or 17 weeks) on F v /F m of five nnul-fruiting rsperry cultivrs during seven dy period. On dy 0, F v /F m ws mesured in the greenhouse efore trnsfer to climte chmer (n = 3). Verticl rs indicte stndrd error of men (n = 3). Fig. 2. The effect of het stress tretment (dys) nd preceding cold-storge durtion (weeks) on diurnl vrition in F v /F m in Polk during seven dy stress period. F v /F m ws not mesured for dy 0 nd 7 in the morning nd evening. Verticl rs indicte stndrd error of men (n = 3 for middy nd n = 9 for morning nd evening mesurements). Fig. 3. The effect of het stress tretment (dys) on chnges in lef (A) chlorophyll, (B) chlorophyll / nd (C) Chlorophyll to crotenoid (+)/( x+c) in percent of greenhouse conditions (20 C) in five nnul-fruiting rsperry cultivrs. Negtive nd positive vlues indicte decrese or increse compred to greenhouse conditions. Verticl rs indicte stndrd error of men (n = 9). Men seprtion ws done using Tukey Krmer s test t P 0.05 nd different letters within cultivr indicte significnt difference. Fig. 4. The effect of seven dy het stress tretment on nthesis (dys) of the terminl flower (A) nd chnges in unopened flower uds in percent of greenhouse conditions (B) in five nnul-fruiting rsperry cultivrs. Negtive nd positive vlues indicte decrese or increse compred to greenhouse conditions. Verticl rs indicte stndrd error of men (n = 9). Men seprtion ws done using Tukey Krmer s test t P 0.05 nd different letters within cultivr indicte significnt difference. 18

19 Tle 1. Min effects nd interctions of cold-storge durtion, temperture nd dys of temperture stress period on quntum efficiency (F v /F m ) in five nnul-fruiting rsperry cultivrs using PROC MIXED with stress period s repeted vrile. Tretments Df Autumn Autumn Tresure Erik Fll Polk Bliss Gold Cold store durtion (C) 2 < < < < Temperture (T) 3 < < < < < C*T < ns Stress period (S) 7 < < < < < C*S < < < ns T*S 21 < < < < < C*T*S 42 < < < Df: degree of freedom; ns: not-significnt t P>

20 Tle 2. Effect of seven dy period of elevted temperture during flower initition on growth nd flowering ehvior in five nnul-fruiting rsperry cultivrs. Lef re Unopened No of Flowering Numer of Min shoot (cm -2 ) xillry lterl lterl shoots flower nd height uds plnt -1 shoots plnt -1 (%) ud lterl - (cm) Temperture plnt -1 1 Autumn Bliss Greenhouse (20 C) c C c C c C c Autumn Tresure Greenhouse (20 C) C C C Erik Greenhouse (20 C) C C C 2498 c Fll Gold Greenhouse (20 C) C C C Polk Greenhouse (20 C) C C C Different letters within the sme column nd cultivr indicte significnt difference t P <0.05 y Tukey-Krmer test; : Lef re of the leves developed fter the temperture stress period; : Dt were log trnsferred prior to sttisticl nlysis ut originl men vlues re shown. 20

21 Tle 3. Effect of cold-storge period on the growth nd flowering ehvior in five nnulfruiting rsperry cultivrs. Lef re (cm -2 ) Unopened xillry uds plnt -1 No of lterl shoots plnt -1 Flowering lterl shoots plnt -1 (%) Numer of flower nd ud lterl -1 Min shoot height (cm) Cold-storge period Autumn Bliss 15 weeks weeks weeks Autumn Tresure 15 weeks weeks weeks Erik 15 weeks 4878 c weeks weeks Fll Gold 15 weeks weeks weeks Polk 15 weeks weeks weeks Different letters within the sme column nd cultivr indicte significnt difference t P <0.05 y Tukey-Krmer test; : Lef re of the leves developed fter the temperture stress period; : Dt were log trnsferred prior to sttisticl nlysis ut originl men vlues re shown. 21

22 C 27 C 32 C 37 C C 27 C 32 C 37 C F v /F m 0.75 F v /F m 'Autumn Bliss' 15 weeks 16 weeks 17 weeks 'Autumn Tresure' F v /F m 0.75 F v /F m 'Erik' 0.65 'Fll Gold' Stress period (dys) 0.80 Fv/Fm Figure 1. 'Polk' Stress period (dys) 22

23 C 27 C 32 C 37 C 0.80 F v /F m weeks Morning Middy Evening 0.80 F v /F m weeks 0.80 F v /F m weeks Stress period (dys) Figure 2. 23

24 'Autumn Bliss' A 'Autumn Tresure' 'Erik' 'Fll Gold' 'Polk' Chnge in Chl (% of greenhouse condition) c c c c B Chnge in Chl / (% of greenhouse condition) c c c c 30 C Chnge in Chl (+)/(x+c) (% of greenhouse condition) C 32 C C 24

25 Figure 3. 25

26 Chnges in dys to nthesis of terminl flower (dys of greenhouse condition) 'Autumn Bliss' A 'Autumn Tresure' 'Erik' 'Fll Gold' 'Polk' B Unopened flower uds (% of greenhouse condition) C 32 C 37 C Figure 4. 26