Growth and yield of three sunflower hybrids cultivated for two years under mediterranean conditions

Transcription

1 Emirtes Journl of Food nd Agriculture (2): doi: /ejf REGULAR ARTICLE Growth nd yield of three sunflower hyrids cultivted for two yers under mediterrnen conditions Yolnd Pptheohri 1, Ilis S. Trvlos 1, Pngiot Ppstylinou 1, Ionnis G. Argyrokstritis 2, Dimitrios J. Billis 1 1 Agriculturl University of Athens, Fculty of Crop Science, Lortory of Agronomy, 75, Ier Odos st., Athens, Greece, 2 Agriculturl University of Athens, Division of Wter Resources Mngement, 75, Ier Odos st., Athens, Greece ABSTRACT Sunflower (Helinthus nnuus L.) is glolly one of the most importnt oil crops. A 2-yers field study ws conducted to evlute growth, grin nd oil productivity of three sunflower hyrids (PR64E83, Oleko nd PR63A90). Plnt height, numer of green leves, weight of 1000-grins nd grin numer were significntly ffected y the interction of yer nd sunflower hyrid. Grin yield resulted to differences rnged mong 13 nd 34 % etween the two yers. In 2009, Oleko nd PR63A90 were the most productive hyrids regrding seed (8210 nd 7500 kg/h, respectively) nd oil (2960 nd 2950 kg h -1, respectively), while PR63A90 ws the significntly more productive hyrid during the second yer (2010). Hyrids such s Oleko seem idel for high grin nd oil yield (with high concentrtion of monounsturted ftty cids); however they fit etter to crop rottion, proly due to high phytotoxicity of their residues which reduces the yield of the second yer. On the contrry, the ility of some non high-oleic hyrids such s PR63A90 to keep high grin yield even in the second yer of their cultivtion in the sme field is clerly very desirle trit nd it should e further tested, since it cn result to very high oil yield. Keywords: Sunflower; High-oleic hyrid; Seed oil yield INTRODUCTION Sunflower (Helinthus nnuus L.) is glolly one of the most importnt rle crops minly grown for edile oil, due to its high oil content, high non sturted ftty cids content nd sence of cholesterol (Lelnd, 1996; De l Veg nd Hll, 2002). Ltely, severl reeding ttempts re towrds the direction of the development of sunflower cultivrs with high oleic cid concentrtion (Flgell et l., 2002; Mohmmdi et l., 2013). These cultivrs re considered to hve high oxidtive stility of their oil (Fuller et l., 1967), which is desirle especilly for processing nd storge. Moreover, diet rich in monounsturted ftty cids hs mny dvntges to offer (Grundy, 1986; Delpnque, 2000). In ddition, sunflower is not only n importnt oil crop ut is lso cultivted for io-energy purposes such s offering n eco-friendly lterntive to diesel fuel (Antolin et l., 2002; Brnwl nd Shrm, 2005). In generl, it could e sid tht sunflower is mong the most cosmopolitn crops with mny uses nd high dptility to diverse envrionments (Berd nd Geng, 1982). In Greece, sunflower is minly grown in the centrl nd northern prt of the country in rottion with plnts such s winter cerels nd legumes (Kllivroussis et l., 2002). As shown in worldwide level, mny fctors such s weeds nd wter deficit cn cuse sustntil yield losses to sunflower nd consequently, the cultivtion of the most suitle hyrids is of mjor importnce (Unger, 1990; Brecci et l., 2011). All these fctors comined with the specific soil nd climtic conditions of ech re mke the predictions regrding the productivity of ech sunflower hyrid even more difficult nd the comprtive evlution of severl hyrids under the sme conditions of mjor importnce, however reltive dt re rther indequte. Therefore, the min ojective of the present study ws to evlute - under the sme conditions - the growth nd productivity (grin nd oil yield nd oil concentrtion) of three sunflower hyrids lredy cultivted in Greece. In prticulr, this study ws conducted in order to see how high-oleic hyrid grows nd yields in comprison with conventionl hyrids under low-input conditions. *Corresponding uthor: Yolnd Pptheohri, Agriculturl University of Athens, Fculty of Crop Science, Lortory of Agronomy, 75, Ier Odos st., Athens, Greece, E-mil: pptheohri@u.gr Received: 25 My 2015; Revised: 03 Novemer 2015; Accepted: 04 Novemer 2015; Pulished Online: 02 Jnury Emir. J. Food Agric Vol 28 Issue

2 MATERIALS AND METHODS Study loction The field experiment ws conducted during 2009 nd 2010 in the experimentl field of the Agriculturl University of Athens (37 ο N, 23 ο E). Soil ws cly lom (CL), the physicochemicl chrcteristics of which (0- to 15-cm depth increment) were cly 352 g/kg, silt 457 g/kg, snd 191 g/kg, ph (1:2 H 2 O) 8.2, 1.75 g/kg totl nitrogen, g/kg ville phosphorus (P-Olsen) nd 0.88 g/kg ville potssium. EC ws 2700 μmhos, CCO g/kg nd orgnic mtter content 24.4 g/kg (Wlkley nd Blck, 1934). Men monthly temperture nd precipittion dt recorded ner the experimentl re re shown in Tle 1. Experimentl detils Three sunflower hyrids, nmely PR64E83 (Pioneer), Oleko (Syngent) nd PR63A90 (Pioneer) were plnted on 27 April 2009 nd 4 My These sunflower hyrids re mong the most cultivted ones in Greece, while one of them (Oleko) is known s high oleic hyrid. They were seeded y hnd in 75-cm rows with distnces within rows of 20 cm. Before plot estlishment ech yer, 27.5 kg N h -1, 16.4 kg P h -1 nd 31.3 kg K h -1 were incorported with hrrow into the soil (inorgnic fertilizer 11:15:15). Plnt emergence egn 5 dys fter sowing nd ws completed within 9 dys fter sowing. The experiment ws set up on n re of 253 m 2 ccording to the split plot design (rndomized complete lock) with three replictes nd three tretments (sunflower hyrids). The plot size ws 5 m 3 m. The distnce mong plots ws 1 m nd the sme distnce ws lso kept mong replictes. Weeds were controlled during the growing seson y severl cultivtion nd hnd-hoeing tretments. Irrigtion nd other common culturl prctices were conducted s needed during the growing sesons. The totl wter quntity pplied ws 292 mm of H 2 O. Mesurements Five mesurements of plnt height, numer of leves, lef re index (LAI), dry weight of leves, stems nd Tle 1: Men monthly rinfll nd temperture during the field experiments in 2009 nd 2010 Month Rinfll (mm) Temperture ( C) Mrch April My June July August Totl inflorescence (if ny) were tken from plnts in the three center rows of ech plot t 45, 59, 75, 88, 106 nd 45, 59, 76, 90, 100 dys fter sowing (DAS) for 2009 nd 2010, respectively. Lef re ws estimted y mens of DT-re meter (Delt-T Devices Ltd, Burwell Cmridge, UK), while dry weights were mesured fter 24 h t 80 o C (Mirlles et l., 1997). Plots were hrvested y hnd on 31 August 2009 nd 26 August 2010 (127 nd 114 DAS, respectively). Yield (grin nd oil) ws determined nd mesurements on the stem dimeter, seed numer nd dry weight of 1000 seeds were lso tken. Seed moisture t hrvest ws 5 % s recorded y MT-PRO (Frmex). Moreover, ftty cids were determined ccording to the interntionlly ccepted methodologies. Oil concentrtion ws determined y mens of the crude ft method s proposed y the Assocition of Officil Anlyticl Chemists (AOAC, 1990). Oil yield ws clculted y multiplying seed yields y the concentrtion of oil in seeds. Sttisticl nlysis Anlysis of vrince (ANOVA) ws conducted for ll dt nd differences etween mens were seprted using Fisher s LSD test t P < All sttisticl nlyses were conducted using the Sttistic 12 softwre pckge (SttSoft, Inc Est 14th Street, Tuls, OK 74104, USA). RESULTS AND DISCUSSION The nlysis of vrince of our dt reveled tht mny growth nd yield prmeters of sunflower were significntly ffected y the sunflower hyrid nd the yer (Tle 2). In prticulr, plnt height, numer of green leves, weight of 1000-grins nd grin numer were significntly ffected y the interction of yer nd sunflower hyrid. The yer on itself ws lso significnt fctor for lmost ll the crop chrcteristics, while it hd no significnt effect on the oil content. Moreover, hyrid s effect ws significnt for ll grin yield nd iomss prmeters of sunflower (Tle 2). The time course of plnt height of sunflower is given in Fig. 1. In generl, the time course did not exhiit mjor fluctutions during the oservtion period. The height of sunflower plnts reched its mximum vlues t 75 nd 88 DAS for 2009 nd 2010, respectively. However, it hs to e noted tht in oth yers sunflower plnts lmost douled their height in the period from 45 to 59 DAS. Moreover, even in most cses there were no significnt differences etween the three hyrids (p>0.05), Oleko ws the hyrid with the higher first growth (until 45 DAS) in oth yers. In generl, plnt height is considered to e geneticlly determined chrcteristic; however, it is significntly ffected y soil nd climtic conditions (Pilli et l., 1995). Emir. J. Food Agric Vol 28 Issue

3 Tle 2: Anlysis of vrince for hyrid (H) nd yer (Y) effects on plnt height, numer of leves dry weight of leves, inflorescences, 1000 seeds, numer of seeds nd oil content of seeds t hrvest Source df Plnt height Numer of green leves DW of leves DW of inflorescences 1000 grin weight Numer of grins Oil concentrtion H ns 2.38 ns 12.48*** 4.79** 5.36** 20.18*** 0.41 ns Y *** 77.51*** 7.03** 52.72*** *** 37.29*** 3.61 ns H Y * 12.01*** 3.05 ns 0.1 ns 3.45* 7.38*** 1.22 ns F test vlues re shown, *P<0.05, **P<0.01, ***P<0.001, ns=not significnt Fig 1. Time course of plnt height of the three sunflower hyrids during the two experimentl periods (: 2009 nd : 2010). Verticl rs denote stndrd errors of the mens. Vinisree et l. (1998) hve shown tht higher plnts re strongly correlted with higher yields, too. However, this ws not true in our cse, since the yer my ply mjor role. Regrding the numer of green leves, there were lso some interesting oservtions (Fig. 2). The rpid erly growth of Oleko resulted to significntly higher lef numer t 45 DAS in 2009, while in 2010 there were not ny significnt differences during the first growth stges. In ddition, from out 75 DAS plnts showed decresing trend of the numer of green leves, since mny of them were in senescence nd dried. In the second yer, this reduction of the numer of green leves during the lst mesurement ws drmtic, rnging from 80 to 100% for ll three hyrids nd my hve een due to comintion of wter deficit nd high ir tempertures. Fig 2. Time course of the numer of the green leves for the three sunflower hyrids during the two experimentl periods (: 2009 nd : 2010). Verticl rs denote stndrd errors of the mens. In Fig. 3, the time course of LAI is lso shown. In 2009, LAI ws higher for Oleko in most mesurements, while the hyrids PR63A90 nd PR64E83 hd higher vlues of LAI thn Oleko during the second yer. This finding could e ttriuted to the different response of ech hyrid under the different climtic conditions of ech yer nd my e relted with differences in the finl yields. The time course of the weight of the inflorescences ws lso rther expected s shown in Fig. 4. However, there ws significnt difference mong the two yers with less grown inflorescences during 2010 compred with the previous yer. Another interesting finding hs to do with the high vlues for Oleko hyrid during 2009 nd the low vlues in 2010 compred to the other two hyrids. The results of the present study hve shown some significnt differences mong yers nd hyrids regrding yields nd yield components. It hs to e noted tht 138 Emir. J. Food Agric Vol 28 Issue

4 Fig 3. Time course of LAI for the three sunflower hyrids during the two experimentl periods (: 2009 nd : 2010). Verticl rs denote stndrd errors of the mens. seed yield resulted to differences rnged mong 13 nd 34 % etween the two yers (Tle 3). There hs een decrese in the yield of 1000-grins in the second yer for ll these hyrids. This could e minly ttriuted to the lower growing seson (hrvest t 127 nd 114 DAS for 2009 nd 2010, respectively) nd therefore mturity period, too. The significntly lower grin yield of Oleko nd PR64E83 in 2010 is certinly relted with the lower weight of 1000-grins nd the lower grin numer per hed. Grin formtion is intensely ffected y temperture nd rdition condition during pollintion. These results re in full greement with De l Veg et l. (2002), reporting tht the decline of grin numer is cused y poor grin formtion during lte sowing dtes which re relted with unfvorle environment condition on pollintion period. It is well-known tht severl environmentl fctors during flowering nd seed-filling cn significntly ffect seed yield (Petcu et l., 2001; Monotti, 2003; Ali et l., 2009). However, even in this cse there re some differentitions, due to significnt hyrid nd yer effects nd their interctions. In our study, especilly in 2010, PR63A90 resulted to significntly higher yield thn the other hyrids (Tle 3). This different response of ech hyrid is clerly relted with the genotype nd the gronomicl chrcteristics of ech hyrid nd hs een previously reported y Trvlos et l. (2014). Oleko nd PR64E83 prefer erly sowing, while in Fig 4. Time course of the dry weight (DW) of the inflorescences for the three sunflower hyrids during the two experimentl periods (: 2009 nd : 2010). Verticl rs denote stndrd errors of the mens. our study, PR63A90 proved to e more flexile in respect with sowing dte. Moreover, phenomen such s llelopthy my hve een involved. It hs een oserved tht sunflower crop hs hrmful effects on the succeeding crops in multiple cropping systems (Irons nd Burnside, 1982; Nrwl et l., 1999). Studies hve indicted tht the hrmful effects of sunflower on other plnt species were due to llelopthic effects, while it is lso crop tht exhiits utotoxicity. Its growing plnts inhiit the germintion nd growth of weeds nd succeeding crops due to ccumultion of phytotoxins from root exudtes nd decomposing crop residues (Lovett, 1982; Rwt et l., 2013). Indeed, sunflower contins severl compounds like terpenoids nd phenolics which re hrmful ginst other plnts (Azni et l., 2003; Mcís et l., 2004; Anjum nd Bjw, 2005). In recent study, Dhim et l. (2012) hve shown differences etween the phytotoxic ctivity of six sunflower hyrids nd their residues effects on succeeding weeds nd crops. It hs to e noted tht in oth yers of their study, PR64E83 ws consistently the hyrid tht resulted to lower fresh weight of ivy-leved speedwell (Veronic hederifoli L.). Tht indictes strong phytotoxic ction y mens of the crop residues of the specific hyrid nd this utotoxicity is proly mong the min resons for Emir. J. Food Agric Vol 28 Issue

5 Tle 3: Yield nd yield components of the three sunflower hyrids during the two yers of experimenttion Yer Hyrid Grin yield (kg h 1 ) 1000 grin yield (g) Grin numer per hed Oil concentrtion (%) Oil yield (kg h 1 ) 2009 PR64E cd Oleko PR63A c PR64E de 40.26c c Oleko 5200e 42.46c c 1770c PR63A c c 3020 Men vlues within the sme column followed y the sme letter(s) re not significntly different using LSD tests t P=0.05 Tle 4: Profile of fts (% of min ftty cids) of the three sunflower hyrids during the two yers of experimenttion Yer Hyrid Percentge of ftty cids Sturted Monounsturted Polyunsturted Plmitic Stetic Elic cis Linelic cis 2009 PR64E Oleko 8.89c c 4.57d c PR63A PR64E c 41.77c c Oleko 8.88c c 5.08cd c PR63A c c Men vlues within the sme column followed y the sme letter(s) re not significntly different using LSD tests t P=0.05 the significntly lower grin yield of PR64E83 in 2010, s shown in Tle 3. This could e lso true for Oleko, ut not for PR63A90. The numer of grins for PR63A90 ws higher during 2010 (resulting to high grin yield), proly ecuse of lower phytotoxic ction of the residues of this specific hyrid, comined with the higher rinfll during June 2010 compred with the previous yer (period of seed formultion). Oil content of sunflower is known to e ffected y the hyrid nd the temperture during seed development (Cnvin, 1965; Skoric, 1992). According to Roertson et l. (1971), high oleic hyrids hve usully oil content of %, while the corresponding vlues for conventionlly hyrids were %. In our study, the high concentrtion of elic cid in Oleko is rther nticipted (Skoric, 1992), however, the high concentrtion in 63A90 ws proly due to cross pollintion nd the insects previously visited the high oleic hyrid (Tle 4). Genotype is considered s the min fctor tht determines the oleic cid concentrtion s previously suggested y Fernndez et l. (1989) nd Izquierdo et l. (2002), however, cross pollintion y honeyees cn ffect the grin yield nd oil content (Nderitu et l., 2008). Moreover, the high tempertures during grin filling until mturity my hve lso plyed n importnt role to the high vlues oserved (Roertson et l., 1971; Anderson et l., 1978; Hzel et l., 1978). Our study lso reveled some significnt correltions mong the severl growth nd yield prmeters of sunflower. For 2009, LAI ws strongly correlted with grin nd oil yield (r=0.98 nd 0.94, respectively). This oservtion is in full ccordnce with previous studies (Mirlles et l., 1997; Dhim et l., 2012). Moreover, dry weight of sunflower plnts ws positively correlted with grin nd oil yield (r=0.95 nd 0.86, respectively). This finding is in greements with results of previous studies (Zffroni nd Schneiter, 1991; Mirlles et l., 1997). In ddition, dry weight of inflorescences is positively nd significntly correlted with dry weight of stems nd numer of grins (0.84 nd 0.79, respectively). Among the severl yield prmeters, grin numer ws found to e the one strongly correlted with the finl grin yield (r=0.92), finding tht is in full ccordnce with previous studies, indicting the mjor importnce of this chrcteristic for finl yields (Zffroni nd Schneiter, 1991). It hs lso to e noted tht there ws not ny significnt correltion etween numer of grins nd weight of 1000 grins (r=0.49, ns). CONCLUSIONS The results of the present study indicted tht the growth nd yield of sunflower hyrids might hve sustntil rnge nd should e certinly tken into ccount for the crop estlishment in ech region. Similr studies should e continued including more sunflower hyrids, soil nd climtic conditions. The ility of some hyrids such s PR63A90, even without eing high-oleic, to keep high grin nd oil yield even in the second yer of their cultivtion in the sme field is certinly very desirle trit nd it should e further studied. On the other hnd, hyrids such s Oleko seem idel for high grin nd oil yield (with high concentrtion of monounsturted ftty cids), however they fit etter to crop rottion, proly due to high phytotoxicity of the residues (exctly s in the cse of PR64E83). Our results highlight the underestimted importnce of sunflower hyrid selection for successful 140 Emir. J. Food Agric Vol 28 Issue

6 estlishment of the crop nd the overll grin nd oil productivity. This is importnt, especilly in griculturl situtions nd regions where crop rottion is not common or widely dopted y the frmers. ACKNOWLEDGEMENTS Authors would like to thnk Filio Moustferi, Christos Christkis, Evgenios Agthokleous nd Kyrikos Christou for their invlule help with field nd experimentl ctivities. Author s contriutions The contriution of ll uthors ws equl in this study. REFERENCES Ali, Q., M. Ashrf nd F. Anwr Physico-chemicl ttriutes of seed oil from drought stressed sunflower (Helinthus nnuus L.) plnts. Grss y Aceites. 60: Anderson, W., R. Smith nd J. Mc Willim A system pproch to the dpttion of sunflower to new environments. I. Phenology nd environment. Field Crops Res. 1: Anjum, T. nd R. Bjw A ioctive nnuionone from sunflower leves. Phytochemistry. 66(16): Antolin, G., F. V. Tinut, Y. Briceño, V. Cstño, C. Perez nd A. I. Rmirez Optimistion of iodiesel production y sunflower oil trnsesterifiction. Bioresour. Technol. 83: Azni, A. A. P., C. A. M. Azni, P. L. C. Alves, R. Plnirj, H. S. Kdin, S. C. Sti, L. S. Rwt, D. S. Dhiy nd S. S. Nrwl Allelopthic plnts. 7. Sunflower (Helinthus nnuus L.). Allelopthy J. 11(1): Brnwll, B. K. nd M. P. Shrm Prospects of iodiesel production from vegetle oils in Indi. Renewle sustin. Energy Rev. 9: Berd, B. H. nd S. Geng Interreltionships of morphologicl nd economic chrcters of sunflower. Crop Sci. 22: Brecci, G., T. Veg, G. Nestres, M. L. Myor, R. Zorzoli nd L. Picrdi Rpid test for detection of imidzolinone resistnce in sunflower (Helinthus nnuus L.). Plnt Breed. 130: Cnvin, D. T The effect of temperture on the oil content nd ftty cid composition of the oils from severl oilseed crops. Cn. J. Bot. 60: De l Veg, A. J. nd A. J. Hll Effects of plnting dte, genotype, nd their interctions on sunflower yield: I. Determinnts of oilcorrected grin yield. Crop Sci. 42: Delpnque, B Intéret nutritionnel oles tournesols. In: Proceedings of XV Interntionl Sunflower Conference, Toulouse, Vol. I. Pp Dhim, K., I. Vsilkoglou, K. A. Pschlidis, T. Gtsis nd R. Keco Productivity nd phytotoxicity of six sunflower hyrids nd their residues effects on rotted lentil nd ivy-leved speedwell. Field Crops Res. 136: Fernndez, J. M., A. Jimenez, J. Dominguez, J. M. Grci, R. Grces nd M. Mnch Genetic nlysis of the high oleic cid content in cultivted sunflower (Helinthus nnuus L.). Euphytic. 41: Flgell, Z., T. Rotunno, E. Trntino, R. Di Cterin nd A. de Cro Chnges in seed yield nd oil ftty cid composition of high oleic sunflower (Helinthus nnuus L.) hyrids in rottion to the sowing dte nd wter regime. Eur. J. Agron. 17: Fuller, M., J. Dimond nd T. Applewhite High oleic sunflower oil. Stility nd chemicl modifiction. J. Am. Oil Chem. Soc. 44: Grundy, S. M Comprison of monounsturted ftty cids nd crohydrtes for lowering plsm cholesterol. New Englnd J. Med. 314: Hzel, C. H., J. R. Mc Willim nd W. K. Mson Influence of temperture on oil content nd composition of sunflower seed. Aust. J. Agric. Res. 33: Izquierdo, N., L. Aguirrezl, F. Andrde nd V. Pereyr Night temperture ffects ftty cid composition in sunflower oil depending on the hyrid nd the phenologicl stge. Field Crops Res. 77: Irons, S. M. nd O. C. Burnside Competitive nd llelopthic effects of sunflower (Helinthus nnuus). Weed Sci. 30: Kllivroussis L., A. Ntsis nd G. Ppdkis The energy lnce of sunflower production for iodiesel in Greece. Biosyst. Eng. 81: Lelnd, E. F Slnity effect on four sunflower hyrids. Agron. J. 88: Lovett, J. V Allelopthy nd self-defence in plnts. Aust. Weeds. 2: Mcís, F. A., A. Lopez, R. M. Vrel, A. Torres nd J. M. G. Molinillo Bioctive pocrotenoids nnuionones F nd G: Structurl revision of nnuionones A, B nd E. Phytochemistry. 65: Mirlles, O. B., J. A. de Jun Vlero nd F. M. de Snt Olll Growth, development nd yield of five sunflower hyrids. Eur. J. Agron. 6: Mohmmdi, K., G. Heidri, M. Jvheri, A. Rokhzdi, M. T. Krim Nezhd, Y. Sohri, nd R. Tlei Fertiliztion ffects the gronomic trits of high oleic sunflower hyrid in different tillge systems. Ind. Crops Prod. 44: Monotti, M Growing non-food sunflower in drylnd conditions. Itl. J. Agron. 8: 3-8. Nrwl, S. S., T. Singh, J. S. Hood nd M. K. Kthuri Allelopthic effects of sunflower on succeeding summer crops. 1. Field oservtions nd iossys. Allelopthy J. 6: Nderitu, J., G. Nymsyo, M. Ksin nd M. L. Oronje Diversity of sunflower pollintors nd their effect on seed yield in Mkueni District, Estern Keny. Spn. J. Agric. Res. 6: Petcu, E., A. Arsintescu nd D. Stnciu The effect of drought stress on ftty cid composition in some Romnin sunflower hyrids. Romn. Agric. Res. 15: Pilli, M. A., P. Rmlingm, C. S. Srodhrn, S. Murugn nd C. Vnnirjn Stility nlysis for seed yield nd it s components in sunflower hyrids. Ann. Agric. Res. 16: Rwt, L. S., R. K. Mikhuri nd V. S. Negi Inhiitory effects of lechte from Helinthus nnuus on germintion nd growth of Khrif crops nd weeds. Act Ecologic Sinic 33: Roertson, J. A., J. K. Thoms nd D. Burdick Chemicl composition of the seed of sunflower hyrids nd open pollinted vrieties. J. Food Sci. 36: Skoric, D Achievements nd future directions of sunflower reeding. Field Crops Res. 30: Trvlos, I. S., D. Billis, P. Ppstylinou, D. Chchlis, I. Lygizos, I. Annouskis, nd Y. Pptheohri Response of the growth nd yield of sunflower hyrids to orgnic nd inorgnic Emir. J. Food Agric Vol 28 Issue

7 fertiliztion. In: Proceedings of the 13th Interntionl Symposium of University of Agriculturl Sciences & Veterinry Medicine Cluj- Npoc Septemer 2014, Cluj-Npoc. Bull. UASVM Hortic. 71(2): Unger, P. W Sunflower. In: Stewrt, B.A., Nielson, D.R. (Eds.). Irrigtion of Agriculturl Crops, ASA Monogrph No 30, ASA- CSSA-SSSA, Mdison, WI, Pp Vinisree, G., K. Annthsyn, G. S. Nghusnnm nd C. A. Jgdish Correltion nd pth coefficient nlysis in sunflower. J. Oilseeds Res. 2: Wlkley, A. nd I. A. Blck An exmintion of Degtjreff method for determining soil orgnic mtter nd proposed modifi ction of the chromic cid titrtion method. Soil Sci. 37: Zffroni, E. nd A. A. Schneiter Sunflower production s influenced y plnt type, plnt popultion nd row rrngement. Agron. J. 83: Emir. J. Food Agric Vol 28 Issue