Does drought stress induce physiological mechanisms in Celtis caucasica L. Seedlings?

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1 Advnes in Bioreserh Adv. Biores., Vol 5 (4) Deember 24: Soiety of Edution, Indi Print ISSN ; Online ISSN Journl s URL: CODEN: ABRDC3 ICV 7.2 [Polnd] Advnes in Bioreserh ORIGINAL ARTICLE Does drought stress indue physiologil mehnisms in Celtis usi L. Seedlings? Fereshteh Kordrostmi¹, Anoushirvn Shirvny 2, Pedrm Attrod 3*, nd Mostf Khoshnevis 4 Deprtment of Forestry nd Forest Eonomis, Fulty of Nturl Resoures, University of Tehrn, Krj, 2Deprtment of Forestry nd Forest Eonomis, Fulty of Nturl Resoures, University of Tehrn, Krj, 3Deprtment of Forestry nd Forest Eonomis, Fulty of Nturl Resoures, University of Tehrn, Krj, 4Reserh Institute of Forests nd Rngelnds, Tehrn, * Corresponding E-mil ddress: ttrod@ut..ir ABSTRACT Drought stress is n importnt environmentl ftor inhibiting plnt growth. The exmintion of physiologil retion of different speies to the drought stress is useful to reognize effetive mehnisms in drought tolerne nd hoosing the suitble speies for plnttion in dry lnds. In order to determine the resistne of Celtis usi nd understnd the physiologil mehnisms in response to the drought ondition, n experiment ws designed in ompletely rndomized blok with one ftor (irrigtion), t five levels (, 3, 5, 7, nd 9 dys) with five replitions hlorophyll fluoresene prmeters (Fv/Fm, Fm nd F) nd pigments ontent (totl hlorophyll, hlorophyll, nd hlorophyll b) of leves. The results indited tht drought stress indued signifint redution t five perent level in mximum photohemil effiieny of photosystem II (Fv/Fm) nd mximum fluoresene (Fm) while the minimum fluoresene (F) ws not signifintly ffeted by drought. With inresing the intensity of drought, hlorophyll ontent in leves ws inresed. Mintining the lef hlorophyll ontent under stress onditions, is one of the physiologil inditors of stress resistne onluding tht C. usi would be one of the most suitble speies for fforesttion plns in rid nd semirid regions. Key words: drought stress, Celtis usi, hlorophyll fluoresene, proline Reeived 2/9/24 Aepted 24//24 24 Soiety of Edution, Indi How to ite this rtile: Fereshteh K, Anoushirvn S, Pedrm A, Mostf K. Does drought stress indue physiologil mehnisms in Celtis usi L. Seedlings?. Adv. Biores., Vol 5 [4] Deember 24: DOI:.555/br INTRODUCTION Drought stress is n importnt environmentl ftor tht ffets plnts growth, produtivity, photosynthesis nd hnges plnts metbolism [23], [24]. Drought stress is one of the most importnt environmentl inhibitor for photosynthesis vi stomtl losure [3].In this ondition, deresing photosynthesis is relted to disturbing the biohemil proesses of the photosyntheti pprtus. Photosystem II is the most sensitive prt of the photosyntheti systems nd plys ritil role in plnts retion to environmentl stresses [3]. Dmge to photosystem II is frequently the first symptoms of stress in lef [23]. Plnt physiologists hve suggested hlorophyll fluoresene s sensitive inditor of stress ondition in plnts. The mesurement of hlorophyll fluoresene in nturl environment is useful tehnique to understnd the tolerne of photosyntheti pprtus of the environmentl stress [23]. This tehnique is nondestrutive nd n be just s opertive s the gs exhnge tehniques to dislose differenes between drought tolernt nd suseptible speies [25]. There hve been mny fluoresene prmeters so tht it is not possible to give n extensive review of ll of these here. F (minimum fluoresene from drk dpted lef is the level of fluoresene when primry quinine eletron eptors of PS II (Q A) re mximlly oxidized (PS II enters re open), F m (Mximum fluoresene from drk dpted lef is the ABR Vol 5 [4] Deember 24 3 P g e 24 Soiety of Edution, Indi

2 level of fluoresene when Q A is mximlly redued (PSII enters re losed), F v(vrible fluoresene from drk dpted lef shows the bility of PSII to perform primry photohemistry (photoredution of Q A) nd F v/f m.the vlues of F v/f m in drk dpted leves indites the potentil yield of the photohemil reting in PSII used s prtil lterntive to monitor the photosyntheti performne [5]. The optiml vlues of F v/f m in helthy leves of most plnt speies re bout.832 [6] nd the lower vlues show the exposure of plnts to stress. This is the onsequene of photo dmge to PSII retion enters, nd the progression of quenhing proess [23], [9]. Literture reviews show tht there re differenes between physiologil responses of plnts to drought stress. These differenes re relted to speies type nd to some extent, experimentl onditions. In the present reserh, C.usi ws employed to study the photosyntheti responses to the drought stress. It is ommonly used s n urbn tree beuse of its bility to withstnd drought nd tolerte in urbn environments. The ims of this study were: (i) to evlute the effet of drought stress on the hlorophyll fluoresene prmeters (ii) to find the reltionship between hlorophyll ontents nd drought tolerne in C. usi nd, (iii) ssessing the vitlity of C.usi in different irrigtion regimes for plnting in semi-rid res. MATERIAL AND METHODS Mterils nd Experimentl design This study ws onduted in the Alborz Reserh Sttion in southwest slope of Alborz mountin in (ltitude 35 o 48 N, 5 o 54 E nd 3 m.s.l) with semi-rid limte where mens nnul temperture nd rinfll re 3.7 o C nd 23 mm, respetively. The seeds were olleted from 7km in the rod of Chloos-Nojn with elevtion of 45m nd in April, 2, they were swn in plsti pots (5 4 m) ontining n equl mixture (2::) of ly, snd nd orgni fertilizer. Pots were irrigted every dy for bout one yer. No rtifiil lighting ws used in this study exluding nturl light from the sun. Regulr mngement ws onduted until the seedlings were bout 5 m height. Twenty five seedlings were seleted rndomly nd lssified to five groups of tretments. Drought experiment strted in August 22. Mesurements were performed on, 3, 5, 7 nd 9 dys fter drought. Soil ws fully drenhed before the experiment. Chlorophyll fluoresene Chlorophyll fluoresene ws mesured using portble hlorophyll fluorometer (PAM 25 WlzGermny) on three fully expnded leves of five pots per tretment. Leves were dpted to drkness for 3 minutes by tthing light lips to the lef surfe. All mesurements rried out every dy, from AM to 4 PM. Chlorophyll ontent To ssess hlorophyll ontent, fresh nd mture leves (.g) were extrted with ml of 8% etone nd entrifuged t 4 rpm for 5 min. The bsorbne ws red spetrophotometri lly t 654 nd 663 nm nd lulted for hlorophyll, hlorophyll b, nd totl hlorophyll ording to [3]. Sttistil Anlysis The normlity of dt ws ssessed using the Kolmogorov-smirnov test nd the homogeneity of vrines ws determined using the Leven s test. The verge of prmeters ws ompred using Dunn or Gmes Howel test.dt nlysis ws performed using SPSS 7.. RESULTS AND DISCUSSION Chlorophyll fluoresene As n be seen in Tble, mximum photohemil effiieny of PSII (F v/f m) nd mximum fluoresene (F m) in C. usi deresed signifintly fter 5 dys drought. During the experiment, the lowest mount of F v/f m rehing.254 fter 9 dys withholding wter. Tble. Fo, Fm nd Fv/Fmvlues inc. usi L. under different wtering regimes. Dt were expressed s men ± SE Tretment F Fm Fv/Fm Men+SE Men+SE Men+SE Control.74± ± ±.8 3d.67± ±.24.74±.8 5d.686± ± ±. b 7d.73± ± ±.2 b 9d.927± ±.46 b.254±.66 Note: Dt in the sme olumn followed by different smll letters re signifintly different t.5 level of signifine. ABR Vol 5 [4] Deember 24 3 P g e 24 Soiety of Edution, Indi

3 The mount of F m in 9 dys drought hs been signifint differenes with other tretments with the mesure of (µmol m -2 s - ). The miniml fluoresene (F ) ws onstnt throughout the entire ourse of the experiment. Most studies showed tht under drought onditions, the redution of photosynthesis ssoited with disorder in biohemil retions[4]. Drought dmges the retion enter of photosystem II [8], [9], [2]. Hene the redution of the mximum photohemil effiieny of photosystem II (F v/f m) nd fluoresene hnges in the time intervl is used s riterion of tolerne nd stress resistne[2]. We found out tht the mximum photohemil effiieny of photosystem II (F v/f m) nd mximum fluoresene (F m) hd downwrd trend with inresing the drought stress. This is in greement with [4] who reported the redution of F v/f m nd F m in seedlings of Pinushlepensis, Querusoifer nd Querus ilex. We lso showed tht C. usi hd signifint differenes in the rtio of F v/f m sine 5 dys nd in F m sine 9 dys fter drought. The high level of F v/f m nd F m indited the high mount of photosynthesis. The F v/f m represents the eletron trnsport pity of photosystem II []. Tht hs high orreltion with quntum yield of net photosyntheti [2]. Aording to Alidib et l., [] derese of effiieny of photosystem II enters to onsumption of photons, exhibited the mesure of photo inhibition under drought stress onditions. The derese in F m reveled tht the lower oxidtion of Q A under drought onditions nd redued photohemil retions. The rpid hnges in fluoresene tht our during the rpid indution to pek hve long been ttrtive for deteting differenes in photosyntheti performne in plnts. On immedite exposure to light, fluoresene rises to the minimum level of fluoresene, termed F level, whih is the fluoresene level obtined when the PSII retion enters re in the open stte, i.e., pble of photohemistry sine Q A, the primry quinone eptor of PSII, is mximlly oxidized. The results indited tht the minimum fluoresene in C.usiws not signifintly ffeted by drought in different tretments. This result is in greement with findings of [] nd [22]. Sine F vlues re relted to hlorophyll fluoresene of PSI reeptors [2], [27] nd onsidering tht non-signifint differene of F between irrigtion regimes, it seems the reeptors of hlorophylls hd lmost similr effiieny between irrigtion regimes. Chlorophyll ontent With the drought proess, Chlorophyll, Chlorophyll b, nd totl Chlorophyll in C. usi hd signifint upwrd trend. Chlorophyll, Chlorophyll b, nd totl Chlorophyll in 9 dys drought were.,.2,.2 times, respetively, in ompre to tht of the ontrol. Chlorophyll (mg g - fw) b Chlorophyll b (mg g - fw) d b bd ABR Vol 5 [4] Deember P g e 24 Soiety of Edution, Indi

4 Totll Chlorophyll (mg g - fw) d b bd Fig.. Effets of different wtering regimes on hlorophyll, hlorophyll b, nd totl hlorophyll of C. usi leve. Vlues re men ± SD nd brs indite stndrd error. Chloroplst pigments ply n importnt role for the light bsorption nd onversion in the photosynthesis proess. Generlly in most plnts the ontents of photosyntheti pigments (hlorophyll) re redued with inresing drought [7]. Reserh showed tht the hlorophyll ontent in plnts with low resistne is deresed with inresing the drought [7], [4]. whih is in ontrdition with our results. In our experiments, hlorophyll ontent of C. usi inresed with drought deepening. Gun et l [6] found tht totl hlorophyll ontent in Moslh hinensis inreses with deresing soil wter ontent. The inrese in hlorophyll ontent my be ssoited with the derese of lef wter ontent during the drought [9]. This my ompenste the reduing lef re under drought stress. Inrese in hlorophyll ontent on one hnd nd reduing lef re on the other n be ttributed to the mintenne of photosyntheti rte under drought stress [24]. Drought stress dmges the retion enters of photosystem II [8], [9]. In our study, the F v/f m vlue deresed with inresing the levels of stress. This derese ws very smll until 7 dys fter drought, refleting C. usi seedlings hs strong bility to tolerte drought stress. We onluded tht C. usi seedlings re resistnt to drought stress. C. usi seedlings n inrese its hlorophyll ontent nd on the other hnd the deline rte of the photohemil effiieny of photosystem II is very smll. Sine the drought dmges the photosyntheti pprtus vi reduing the pity of eletron eptne, it hs negtive impt on the photohemil effiieny of photosystem II [22]. This indites the higher photosyntheti effiieny of C. usi under drought onditions. The results of hlorophyll fluoresene onfirm tht signifint inrese in hlorophyll ontent under stress enhnes the exittion pity of photosystem II being one of the physiologil inditors of stress resistne. C. usi would be one of the most suitble speies for fforesttion plns in rid nd semirid regions. REFERENCES. Ali-Dib T., Monneveux PH., Aevedo J. nd Nhil MM. (994). Evlution of prline nlysis nd hlorophyll fluoresene quenhing mesurements s drough tolerne inditors in durum whet (Tritium turgidum L. Vr. durum). Euphyti.: 79 (-2 ): Anonymous: (993). An introdution to fluoresene mesurements with the plnt effiieny nlyzer.(pea) Hnsteh Instruments Ltd. Englnd. 3. Arnon DI: (949). Copper enzymes in isolted hloroplst polyphenol oxidse in Bet vulgris. Plnt Physiol. 24: Bquedno FJ., Cstillo FJ: (26). Comprtive eophysiologil effets of drought on seedlings of the Mediterrnen wter-sver Pinushlepensis nd wter-spenders Querusoifer nd Querus ilex. Trees. 2: Brker DJ., Sullivn CY. nd Moser. (993). LE Wter defiit effets on osmoti potentil, ell wll elstiity, nd prlin in five forge grsses. Agronomy Journl. 993: 85: Bjorkmn O., Demming B: (987). Photon yield of O2 evolution nd hlorophyll fluoresene hrteristis t 77 K mong vsulr plnts of diverse origins. Plnt.: 7: Bure JA: (99). Comprtive responses of lef ondutne to humidity in single tthed leves. Journl of Experimentl Botny. 32: Comi G., Britis JM:(99). Prtioning of photosyntheti eletron flow between Co2& O2 redution in C3 lef (Phseolus vulgris L.) t different Co2 onentrtion & during drought stress. Plnt. 83: ABR Vol 5 [4] Deember P g e 24 Soiety of Edution, Indi

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