Effect of Thiourea on Dormancy Breaking and Yield of Potato (Solanum Tuberosum L.) Minitubers Marfona cv. in Greenhouse

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1 211 Interntionl Conferene on Environmentl nd Agriulture Engineering IPCBEE vol.15(211) (211) IACSIT Press, Singpore Effet of Thioure on Dormny Breking nd Yield of Potto (Solnum Tuerosum L.) Minituers Mrfon v. in Greenhouse Srdr Germhi 1, Frimh GhnndiBehroozi 2 nd Smir Bdri 3 1 Memer of Young reserher Clu, Islmi Azd University, Ardeil rnh 2 MS of plnt reeding, Islmi Azd University, Triz rnh, Irn 3 MS of seed siene nd tehnology, Tehrn University, Tehrn, Irn Astrt. This experiment ws onduted for studying thioure pplition effet on potto minituers dormny reking in Mrfon ultivr in greenhouse in 28. Thioure in three levels s,.5, nd 1% rrnged in ompletely rndomized design in three replites. After dormny reking, ttriutes like s dys to sprouting, length of the longest sprout, nd sprout numer mesured. Then minituers plnted in pots nd dys to emergene, min stem numers, nd plnt height mesured. Tuer numer per plnt, yield nd men tuer weight ws lulted fter hrvesting. Results showed tht thioure hd signifint effet on ll ttriutes exept of sprouts numer nd length of sprouts. Applying 1% thioure deresed dys to sprouting dte from 12 to it less thn 9 dys, deresed dys to emergene from 38 to 28 dys, inresed stem numer from 1.2 to 2.1, inresed plnt height t lest 28 m, inresed tuer numer per plnt from 4 to 8, deresed men tuer weight per plnt t lest 25 g nd inresed totl tuer weight per plnt from 15 to more thn 185 g. Therefore, pplying 1% thioure is reommendle for minituers dormny reking euse of its effet on rpid dormny reking, rpid emergene, nd inresing minituer numer per plnt nd inresing tuer yield in Mrfon minituer prodution. Key words: dormny period, thioure, totl tuer weight. 1. Introdution Potto (Solnum tuerosum L.) is onsidered s n importnt nd strtegi produt, hving the seond rnk in terms of prodution nd third one ording to its importne mong other produed foods in Irn (1). In reent yers, the most effiient wy of ontrolling nd removing viruses in potto is produing helthy plntlets in lortory onditions through omining het-therpy nd ulturing meristemti ells of this plnt in order to produe miro nd minituers (12). Potto minituers re not plnt le immeditely fter hrvest nd during unknown period fter tht, so they hve dormny period during whih the tuers will never germinte. Durtion of dormny in potto minituers depends on ultivr, ripening time, growth ondition, mintenne ondition in store nd the tuer size. Minituers Dormny period is longer thn norml seed tuers (3, 9, 2 nd 21). In some regions, it is possile to ultivte potto more thn one time in yer or the time etween plnting nd hrvesting of minituers is shorter thn seeds dormny period, nd seed tuers my still e dormnt nd do not produe sprout even in suitle onditions. In these onditions nd in reeding nd produing virus-free seeds progrms in ommeril prodution, it is essentil to rek down the dormny period. Minituers dormny period n e removing y setting the store temperture, utting the tuers, nd treting y hemils. Treting minituers with hemils is sfe nd onfident method. Among the Corresponding uthor. Tel.: ; fx: E-mil ddress: Srdr1983@yhoo.om. 19

2 hemils pplied for reking down the potto nodes dormny, one n refer to GA 3, thioure, ethylene, ethyl romide, nd ron disulphide (11, 13 nd 18). Thioure is tlyse inhiitor, whih triggers potto tuers germintion nd heling tuers injuries. Thioure solution in n pproprite onentrte not only filittes germintion, ut lso produes more thn one sprout in eh eyes of potto, so tht, thioure domintes over inhiiting effets of mjor sprout on minor ones in eh eye, nd neutrlizes terminl uds pity to stop lower uds growth in seeding tuer. It is reported tht using thioure tretment nd/or pplying H 2 O 2 enles one to remove tuers dormny (2). In ddition, it is pointed out tht treting ut tuers or newly hrvested ones y 1-2% thioure solution for 1 to 2 hours (18) nd y 3% for 1 hour (16) reks dormny. Studies on morphologil ltertions in tuers sprouts hve shown tht expression of 2 to 3 mm of primry sprout is trustle riterion for determining the end of dormny period (19). Hssn-Pnh et l. (5), surveying GA 3 tretment effet with onentrtion of 15 ppm nd 5% thioure to rek dormny of Agri minituers, onluded tht this tretment dereses dormny period from 63 dys to 39 dys, lso they showed tht the tuer yield nd its weight per plnt re delined fter sewing seeds in the greenhouse. Ju et l. (7), studying different hemils in reking minituers dormny, found tht thioure effet is etter thn other tretments (IAA nd GA 3 ) nd, through sinking minituers in thioure solution with 1% onentrtion for 1 hour in 25ºC, the fst germintion ourred nd strong sprouts were produed. Ksrwi nd Alfyyd (8), lso, reported tht using GA 3 hormone with 5 ppm onentrtion y itself or in omintion with 1% thioure is more effiient in inresing sprouts numer nd length in 5 vrieties of norml tuers of potto thn ontrol tretments. In nother experiment performed y Pietkiewiz (14) to ompre the effets of some hemils on potto norml tuer dormny period, it ws delred tht treting the tuers y mixing GA 3 with 1 ppm onentrtion nd thioure with 1% onentrtion inreses the plnt growth nd dereses dormny period signifintly in omprison with other tretments. 2. Mterils nd methods 2.1. plntlets prodution: Using omintion method of het-therpy nd meristem isoltion, nd tissue ultured in liquid medi of M.S on pper ridge, nd then trnsferred the ultures to n pproprite growth ondition in growth hmer, nd virus-free potto plntlets of Mrfon ultivr were produed. The plntlets ultured on the solid Agr MS ulture medi, nd then trnsferred to the growth hmer with 24 ºC, 16 hours light s 45 lux intensity, nd kept there for 4 weeks until omplete growth (11) minituers prodution in greenhouse: After hieving the required plntlets, the 25-3 dy ones tht hve 7-9 leves were seleted to trnsfer to the greenhouse. Then, the plntlets were tken out of the pot ulture medi. The lened plntlets were refully moved into ed ontining of soil, sterile with fungiides nd insetiides (Cptn nd Sevin), perlite nd pit mss with 1:2:1 rtio. In order to eing omptile with greenhouse environment, nd to protet them ginst ny injury, the plntlets were overed with plsti ps for few dys. The plntlets were grown up in greenhouse with 18ºC nd 12ºC in dy nd night tempertures, 12 hours of dy length nd 85% reltive humidity. Approximtely, fter 1 dys, the minituers were tken out nd trnsferred to the lortory to do the experiments (6) Treting minituers with thioure: This reserh ws sed on ompletely rndomized design (CRD) in three replitions. Thioure ws redy in two onentrtions (.5% nd 1%). 45 minituers of Mrfon ultivr were wshed with distilled wter immeditely fter hrvesting to remove surfe soils nd then eh 15 minituers were seleted rndomly, nd immersed in vrious tretment of thioure for one hour in 18ºC of lortory ondition. After pplying the tretment, the minituers were dried nd eh 5 tuer were put in one replition nd kept in store with 9% reltive humidity, solute drkness in 18ºC until dormny elimintion (17). The ontrol tretment, without thioure pplition, eing wshed with distilled wter ws put in stndrd store 2

3 ondition immeditely fter hrvesting. Germintion of 2 mm sprout out of minituers is good riterion for end of dormny period, nd this time ws onsidered s dormny reking time (19). Assys were dily done during dormny rek period in the lortory. Finlly, ttriutes s dy numer until sprout germintion, numer of sprouted minituers, numer of sprouts in eh minituer, nd the longest sprout were reorded Surveying the treted minituers in greenhouse: After reking dormny, the minituers were moved into the greenhouse nd ultivted in 5 m depth of pots soil ording to the CRD with three replitions. Following germintion of sprout nd plnt growth, mintenne opertions inluding irrigtion one every 7 dys, fertiliztion nd soil dressing were performed. During growth period, fetures suh s the dys to emergene, numer of min stem, nd plnt height were mesured. After 4 months nd t the end of growth period, the tuers were olleted nd fetures suh s numer of tuers per plnt, tuer totl weight, nd men of produed tuer weight per plnt were lso mesured. Dt vrine nlysis were performed y MSTAT-C sttistil softwre. The mens were ompred y Dunn multi-dimension test t 5% signifition level. 3. Results nd disussion Vrine nlysis of thioure effet in lortory ondition indited tht thioure did not hve ny signifint effet on the numer of sprouts lso length of sprout ppered on minituers ut, hd signifint effet on the numer of dys to sprouting t 5% signifition level (tle 1). Compring mens of thioure effets (fig.1) showed tht onsuming.5% of thioure dereses period of sprout germintion from 12 dys to 92 dys in omprison with ontrol tretment. Results hieved from this reserh re onformed to those estlished y HssnPnh et l (5), Rhmn et l.(15) Ksrwi nd lfyyd (8), Germhi nd et l (4) nd Ju et l (7) on quik sprout germintion in tuers treted with thioure. However, if the purpose is to mke minituers redy for ultivtion, using thioure solution with.5% onentrtion would e suffiient (fig.1). Soures of vrine Degree of freedom Sprout No. Mens squres longest sprout length No. dys till sprout germintion Thioure * error CV (%) *nd**indite signifition t 1% nd 5% proility levels, respetively. Tle 1: vrine nlysis of Thioure effet on underlying fetures in the lortory ondition. Tle of vrine nlysis of thioure effet in greenhouse onditions (tle 2) showed tht thioure effet is signifint on ll the fetures. Compring mens of different levels of thioure onsumption on the germintion period (fig.2) showed tht using t lest.5% onentrtion of thioure deresed germintion period from 39 dys to out 32 dys in omprison with the ontrol. The lest numers of dys until plnt germintion with 1% solution of thioure for 29 dys ws possile whih hd signifint differene with lothes onentrtion of this mteril nd with ontrol tretment. HssnPnh et l (5) nd Germhi et l (4) reported similr results. Using thioure with.5% onentrtion inresed stem numers per plnt from 1.3 to 1.8. The highest stem numers per plnt with 2.2 were oserved in 1% solution of thioure, whih hd signifint differene with other onentrtions (fig.3). Thioure vrious onentrtions effet on plnt height is indited in figure 4. As n e seen from the figure, pplying t lest.5% solution of thioure inresed plnt height up to 28 m. There re negtive link etween plnt height nd numer of dys until germintion. Using thioure mkes plnts germinte 1 dys 21

4 fster (fig.2). As result, y deresing numer of dys to emergene, plnt height inresed (fig.4). There ws no signifint differene etween.5 nd 1% thioure onsumption on plnt height. Using thioure inresed signifintly numer of tuers per plnt (fig.5). Aording to positive reltionship etween tuer numers per plnt with plnt height, it seems tht strong plnts produe more tuers. Using.5% solution of thioure inresed verge tuer numer per plnt from 4 to 6.5, while using 1% solution inresed tht to 8. There ws signifint differene etween vrious levels of thioure in terms of this feture (fig.5). Moreover, signifint differene ws oserved etween using.5 % of thioure nd ontrol tretment in respet of totl weight of tuer per plnt, lso, inresing thioure onentrtion to 1% inresed signifintly tuer yield per plnt to more thn 185 g (fig.6). It seems tht thioure y inresing plnt height, lso stems numer nd deline emergene period, led to inrese tuer weight (18). Using thioure deresed single tuer weight signifintly. Although, oth tuer numer nd tuer yield were inresed in plnt through using thioure, tuer numer per plnt hd fst trend or more slope, s result, single tuer weight per plnt ws highly deresed nd rehed from 32 g in ontrol tretment to it less thn 25g in tretment with 1% of thioure (fig.7). Soures Mens squres of df Dys to Min Tuer per Tuer Tuer men vrine Plnt height emergene stem/plnt plnt weight/plnt weight Thioure **.671** ** 6.632** * 52.9** error / CV (%) *nd**indite signifition t 1% nd 5% proility levels, respetively. Tle 2: vrine nlysis of Thioure effet on underlying fetures in the greenhouse ondition. No. dys till sprouting dy to emrgene stem numer thioure onentrtion (%) thioure onentrtion (%) thioure onentrtion (%) Fig.1: effet of thioure on dys to sprouting in l stem height m thioure onentrtion (%) Fig.4: effet of thioure on plnt height Fig.2: effet of thioure on dys to emergene tuer numer thioure onentrtion (%) Fig.5: effet of thioure on tuer numer per plnt tuer men weight (g) thioure onentrtion (%) Fig.7: effet of thioure on tuer men weight per plnt 22 totl tuer weight (g) Fig.3: effet of thioure on stem numers thioure onentrtion (%) Fig.6: effet of thioure on tuer weight

5 4. Reommendtions Aording to ove mentioned sujet, using thioure solution with 1% onentrtion delined emergene time from 12 dys to it lower thn 9 dys, inresed tuer numer from 4 to 8 per plnt nd lso inresed totl tuer weight per plnt from 15 g to more thn 185 g in omprison whit the ontrol. If our purpose is to mke minituers redy for ultivtion, using 1 % thioure is suggested for reking dormny, elerting plnts emergene, inresing tuer numer per plnt, nd getting mximum yield in potto minituers of Mrfon. 5. Referenes: [1] Anonymous. FAO ft sheets [2] M. Bjji, M.M. Hmdi, F. Gstiny, J.A. Rojs-Beltrn, nd P. Jrdin. Ctlse inhiition elertes dormny relese nd sprouting in potto (Solnum tuerosum L.) tuers. Biotehnology Agronomy Soil Environmentl. 27, 11 (2): [3] B. Emilson. Studies on the rest period nd dormnt period in the potto tuer. At. Agriulture. Suen. 1999, 3: [4] S. Germhi, M.B. KhorshidiBenm, D. HssnPnh, M. Yrni, nd A. Frmrzi. Effet of Thioure on dormny reking nd performne of Agri minituers in green house nd lortory. Journl of New Agriulturl Siene. 21, 18 (6): [5] D. HssnPnh, R. Shhryri, A. Shmel, nd L. Fthi. Effet of thioure nd GA on Agri's mini tuer dormny reking. Proeeding of 5th Irnin Hortiulturl siene reserh Center. Shirz University, 1-4 sep. Shirz, Irn. 27, p 1. [6] D. Hssn-Pnh, R. Shhryri, nd M. Irhimi. Potto minituer ultivtion. Rhro Dnesh Pu. 25. Pp 42. [7] Y.L. Ju, L. GU, B.J. Wng, L. Jing, nd Z.M. Luo. Studies on dormny reking in virus-free potto minituer. At Agriulture Boreli Sini. 21, 16 (4): [8] M.A. Ksrwi, nd M. Alfyyd. Yield nd qulity of pottoes s influened y reking dormny of tuer seed. Reserh Journl of Aleppo University (Syri), Agriulturl Siene. 1989, 13: [9] W.J.M. Lommen. Effet of weight of potto minituers on sprout growth, emergene nd plnt hrteristis t emergene. Potto Reserh. 1994, 37 (3): [1] W.J.M. Lommen. Bsi studies on the prodution nd performne of potto minituers. PhD Thesis, Wgeningen University, Wgeningen, the Netherlnds. 1995, 181 pp. [11] A. Mortzvi Bk. Sientifi report nd tehing of rpid propgtion of potto. SPII. Isfhn Agriulturl nd Nturl resoures. 1989, pp 96. [12] A.R. Mosley, S. Yilm nd B.A. Chrlton. Prodution of pre-nuler potto seed from meristem to minituers. Oregon stte university, Potto projet. 27, [13] M. Otroshy, nd P.C. Struik. Utiliztion of tissue ulture tehniques in seed potto tuer prodution sheme. PhD Thesis, Wgeningen University, Wgeningen, the Netherlnds. 26, 264 pp. [14] E. Pietkiewiz. Comprison of the effiieny of reking tuer dormny with some hemils. Biuletyn Instytutu Ziemnik, Polnd. 1983, 3: [15] F. Rehmn, K.L. Seung nd H. Joung. Effets of vrious hemils on rohydrte ontent in potto miro tuers fter dormny reking. Journl of Plnt Siene. 22, 1 (3): [16] F. Rehmn, S.K. Lee, A. Khir, H.V. Joung nd R.Y. Yd. Evlution of vrious hemils on dormny reking nd susequent effets on growth nd yield in potto miro tuers under greenhouse onditions. At Hortiulture. 23, 619: [17] K. Rykzewsk, The dormny period of minituers of five potto ultivrs. Biuletyn Instytutu Ziemnik. 1996, 47: [18] A. Rezee, nd A. Soltni. Potto Prodution. Mshhd University Pulition, Irn [19] M.K. Vn Ittersum, nd P.C. Struik. Reltion etween stolon nd tuer hrteristis nd the durtion of tuer 23

6 dormny in potto. Netherlnds Journl of Agriulturl Siene. 1992, 4: [2] S.G. Wiersem, R. Cello nd R.h. Booth. Storge ehvior nd susequent field performne of smll seed pottoes. Tropil Siene. 1987, 27: [21] A. Yshr, M. Adoll nd M. Adel. Effets of seed tuer size of some potto ultivrs on produtivity of utumn plnttion. Austrlin Journl of Agriulture Siene. 1995, 26 (2): 1. 24