Yield, berry quality and physiological response of grapevine to foliar humic acid application

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1 DOI: Yield, erry qulity nd physiologicl response of grpevine to folir humic cid ppliction Gheorghe Cristin Popescu 1, Monic Popescu 2* 1.Universitte din Pitesti - Deprtment of Applied Sciences nd Environment Engineering - Pitesti, Romni. 2.Universitte din Pitesti - Deprtment of Nturl Sciences - Pitesti, Romni. ABSTRACT: Environmentlly friendly grpe growing is n importnt ojective of modern viticulture. The im of the study ws to exmine the response of two grpevine Vitis vinifer L. cultivrs to humic cids (HA) folir ppliction s iostimulnt in order to provide sustinle viticulturl prctices for frmers. The experiment ws crried out under field conditions nd repeted in two consecutive yers. In order to evlute the effect of humic cids ppliction, the grpevines were treted with three concentrtions: 30 ml.l -1 ( ), 40 ml L -1 ( ) nd 50 ml L -1 ( ). The grpevines were represented y two grpe vrieties: cv. Fetesc Regl (cv. FR) nd cv. Riesling Itlin (cv. RI). Folir sprys with humic cid derived from vermicompost t concentrtion of 50 ml L -1 induced significnt increse in the totl lef re, yield nd totl solule solids. For severl mesurements performed in plnts we found no significnt difference etween grpevines treted with nd those with HA. The experimentl T3 results in the present study confirm tht folir ppliction with humic cid my improve growth, yield, nd erry qulity ttriutes of grpevine. Key words: iostimulnts, humic cids, physiologicl response, sustinle viticulture, Vitis vinifer, yield nd erry qulity, vermicomposts. *Corresponding uthor: monic_26_10@yhoo.com Received: Jn. 25, 2017 Accepted: Jun. 27, 2017 Brgnti, Cmpins, Ahed of print,

2 G.C. Popescu nd M. Popescu INTRODUCTION Grpevine (Vitis vinifer L. ssp. stiv) is n importnt horticulturl crop, one of the erliest domesticted non-climcteric fruit crops, nd one of the most importnt perennil crops grown in Romni, used especilly s tle fruit, dried risins, nd for the vitiviniculturl industry. In 2015, the totl re under vines in Romni vineyrds ws h nd totl wine production ws mil hl. In recent yers, new strtegies, methods, instruments, nd technologies hve een studied in order to improve the sustinility of griculturl ecosystems. A potentil tool to improve the gro-enviromentl perfomnce in frms is the use of humic cids s plnt iostimulnts. These ctive nturl compounds otined from soil nd compost orgnic mtter cn enhnce yield nd qulity prmeters of crops, nutrient efficiency, physiologicl performnce of horticulturl crops, nd iotic stress tolernce (Clvo et l. 2014). However, the potentil of humic cids for grpevines hs received little reserch ttention. Cnells et l. (2015) reported tht most humic sustnces used in griculturl systems re in the present produced from non-renewle resources. This is why new sustinle sources of humic commercil products need to e identified. Vermicomposts could e potentil source to develop new humic commercil products. Aguir et l. (2013) noted tht vermicomposts re n environmentlly friendly sustitute for pet nd tht it is enriched with highly ioctive humic cids sustnces. Folir pplictions of iostimulnts hve een widely recognized to improve plnt growth, yield nd physiologicl processes of horticulturl crops. Folir pplictions require fewer mounts of iostimulnts nd it llows for nutrients to e sored fst nd directly y the lef. According to Ferrr nd Brunetti (2010), folir sprys of humic compounds pplied t different plnt phenologicl growth stges increses erry weight nd it enhnced grpe fruit qulity prmeters such s titrtle cidity nd solule solids. Trditionlly, vineyrd fertiliztion is mnged y dding different fertilizers directly to the soil, which my increse the risk of nutrient pollution nd reduce the sustinility of griculturl systems (Grde-Cerdán et l. 2014). One solution is to use folir pplictions ecuse this technique is quicker nd more precise (Ls et l. 2012). In order to overcome nutrient deficiency in gro-ecosystems, folir fertiliztion is n importnt prctice incresingly pplied in griculture (Sir et l. 2014). Folir ppliction with iostimulnts my improve the uptke nd the efficient use of nutrients. Humic cid pplictions represent sustinle solution for griculturl systems to e integrted in new eco-friendly pproches for future griculture. Biostimulnts my hve positive effects on plnt growth due to n improvement of physiologicl processes nd in plnt nutrient cquisition. Thus, the im of this work ws to evlute the efficcy of the folir ppliction of humic sustnces derived from vermicompost, on the physiologicl ctivity, yield nd erry qulity ttriutes of grpevines. In the current study we present the results of two-yer field experiment with two locl commercil wine grpevine cultivrs. MATERIAL AND METHODS Vineyrd description, growth conditions, nd experimentl design Romnin viticulturl res re divided into 8 regions nd 37 production res. Stefnesti is one of the most importnt nd suitle loctions for viticulture in Romni. A two-yer field experiment ws conducted in Stefnesti non-irrigted mture vineyrd t 270 m ltitude locted etween lt nd N, long nd E. The climte of this re is continentl temperte. Long-term records show tht the men nnul precipittion is 644 mm. The men nnul temperture is 9.6 C 10.1 C nd the insoltion durtion during the vegettive period is 1430 hours. The soil in the experimentl vineyrd ws luvisol (IUSS Working Group WRB 2006), slightly cronted, medium levels in ville P nd K nd low in ville N. The ph of the soil is slightly cid. The vineyrd ws non-irrigted nd hd trellis system. The vines hd een pruned s Guyot doule with mix of cnes nd spurs on the semi-stem sustined on drperies with 3 wires. The vines were plnted t 2.4 m etween rows nd 1.2 m within rows (3472 vines per hectre) with North South row orienttion. The vines were grfted on rootstock hyrid Koer 5 BB (Vitis erlndieri x Vitis ripri). The grpevines selected for this study included two vrieties, Vitis vinifer cv. Fetesc Regl (henceforth RF) nd cv. Riesling Itlin (henceforth RI). These occupy lrge res in Romnin viticulture nd they re widely used y the winemking industry. The cultivrs hve white erry colors. Grpes otined from these cultivrs re excellent to mke 2 Brgnti, Cmpins, Ahed of print, 2018

3 Physiologicl response of grpevine to humic cid white wine with PDO (protected designtion of origin) lels in order to stisfy qulity stndrds. Fetesc Regl is the most cultivted cultivr in Romni, with h in 2015, nd Riesling Itlin, with 5853 h, occupies the fourth plce. In this experiment we used commercil humic cids (BioHumusSol Compny Ltd., Romni) t the pre-loom nd fruit set phenologicl stges ccording to the BBCH scle (Lorenz et l. 1995). BioHumusSol, ville in liquid form, is nturl iostimulnt product sed on humic cids extrcted from composts using erthworms. This product is comptile with orgnic production for use s crop fertilizer, ccording to the guidelines of Europen Union lws. The nutrient content of BioHumusSol product is: 14.5 g humic sustnces L -1, 19 ppm nitrte nitrogen (NO 3 -N), 104 ppm mmonium nitrte (NH 4+ -N), 22.5 ppm P, 132 ppm K +, 39 ppm C 2+, 75 ppm Mg 2+, 75 ppm N +. During the two-yer field experiment there were no other fertilizer pplictions. Pest control, soil mngement nd other viticulturl opertions were conducted ccording to stndrd prctices. The field tril ws estlished for two consecutive growing sesons: nd In fctoril experimentl design, three different concentrtions of humic cids nd control were used s tretments. Tretment plots were seprted from ech other y n untreted row. Ech tretment plot ws 86.4 m 2 nd hd three rows of ten plnts per row. In order to minimize possile contmintion effects from nery tretments, dt ws collected only from the inner rows of ech plot. During ech folir humic cid ppliction the folige of ech plnt ws fully wetted. The cultivrs were mnully treted with folir humic cids t three different concentrtions: 30 ml.l -1 ( ), 40 ml.l -1 ( ) nd 50 ml.l -1 ( ). The control plnts were mnully spryed with tp wter lone. Folir spry tretments with commercil humic cids were performed twice: t the pre-loom nd fruit set phenologicl stges. Dt nd Mesurements Effects of the folir tretments with humic cids on lef growth were expressed using the following prmeters: totl lef re (m 2.vine 1 ), lef fresh weight, nd lef dry weight. These mesurements were performed on mture leves, efore hrvest time, when shoot growth hd reched its pek. The collected lef smples, preserved in the ice ox t 4 C, were trnsported to the lortory for estimtion of physiologicl prmeters. In order to evlute the physiologicl response of folir ppliction with humic cids, the following were determined: photosynthesis rte (µmol CO 2 m -2.s -1 ) in leves, the content of chlorophyll (Chl, mg.g -1 ), chlorophyll (Chl, mg.g -1 ), nd crotenoids (Cr, mg.g -1 ) in leves. Photosynthesis rte ws determined with S151 Infrred CO 2 portle plnt nlyzer (IRGA from Quit Biology Inc., Ontrio, Cnd). During testing, photosynthetic photon flux density ws μmol.m -2.s -1, ir temperture ws 25 ºC ± 2 С, nd mient reltive humidity ws etween 55% nd 60%. Photosynthetic pigments were determined using spectrophotometer (BOECO S-20VIS from Boeckel & Co, Hmurg, Germny). Leves were collected in the morning, nd trnsported to the lortory where photosynthetic pigments were extrcted in 80% cetone. The mounts of chlorophyll, chlorophyll nd crotenoid pigments were clculted ccording to the formul descried y Holm (1954). Yield of vines nd some grpe qulity prmeters were evluted t hrvest time in 2014 nd The following prmeters were mesured: yield (kg.vine -1 ), cluster weight, 100 erries weight, erry volume (ml.100 erries -1 ), totl solule solids ( Brix), nd titrtle cidity (g H 2 SO 4 L -1 ). For ech vine from the experimentl unit grpes were mnully collected t hrvest time. The fresh weight nd the volume of 100 erries from ech smple were recorded. Totl solule solids (TSS) were determined using n Ae refrctometer. Titrtle cidity (TA) ws mesured with sodium hydroxide titrtion. Titrtle cidity ws expressed s sulfuric cid (g.l -1 ). Finlly, two importnt indexes for evlution of efficcy of lef re to fruit yield nd for informtion out the hstening or dely of the ripening process were clculted: the lef re to yield (m 2.kg -1 ) nd the Brix/TA rtios. Dt nlysis The experimentl design consisted of rndomized complete lock with four tretments nd three replictes. A sttisticl nlysis ws performed using the ANOVA in the SPSS 16.0 softwre. Dt ws nlyzed using the SPSS 16.0 sttisticl softwre (IBM Corportion, Armonk, New York, USA). Mens were compred using Duncn s multiple rnge tests t p < The results of this study re expressed s mens. Stndrd devitions of the mens were clculted. Brgnti, Cmpins, Ahed of print,

4 G.C. Popescu nd M. Popescu RESULTS AND DISCUSSION Physiologicl nd growth response to folir humic cid ppliction In the current experiment, the effects of folir tretments with humic cids on lef development were evluted y determining the following prmeters: totl lef re, lef fresh weight, nd lef dry weight (Tle 1). The results showed tht the totl lef re nd the lef fresh nd dry weight in oth cultivrs incresed with some tretments, nd tht there were some significnt differences etween grpevines treted with or nd control smples. Totl lef re of cv. Riesling Itlin plnts hd the sme sttisticl trend in 2015 s in 2014 to the folir ppliction of humic cids. Regrding lef dry weight in cv. FR during oth growing sesons we found no significnt differences etween tretments. The mximum lef development of cv. FR nd cv. RI plnts occurred with humic cids t 40 ml.l -1 nd 50 ml.l -1 ( nd ). No significnt differences regrding the lef growth fetures of cv. FR nd cv. RI during 2014 nd 2015 sesons were found etween the untreted grpevine nd 30 ml.l -1. In the cse of cv. FR plnts, the influence of or on lef development did not show ny significnt difference during the two yers of study, except in the cse of lef fresh weight nd totl lef re oserved in Studies regrding the effect of folir ppliction of humic cids on grpevine re still limited. Only few studies hve een pulished minly for tle grpevine (Sánchez-Sánchez et l. 2006; Ferrr nd Brunetti 2008; Ferrr nd Brunetti 2010; Mohmdinei et l. 2015). Ferrr nd Brunetti (2010) oserved tht the folir ppliction of humic cids improves grpevine production. Generlly, experiments relted to humic cid ppliction on plnt growth nd its development were conducted in controlled environments, nd few open-field experiments hve een reported. Ahmd et l. (2013) showed tht humic cids folir ppliction provides positive influence on growth, vse life, nd corm chrcteristics of gldiolus. HA hve een shown to hve positive effect, especilly to stimulte plnt growth nd consequently yield for severl horticulturl crops: gerer (Hghighi et l. 2014), gldiolus (Ahmd et l. 2013), nd tomtoes (Olivres et l. 2015). The physiologicl mechnisms of the humic cid, pplied s iostimulnt on grpevine, were investigted in terms of photosynthesis nd ssimiltory pigments in leves. Chlorophylls nd crotenoids re the min pigments of lef photosynthesis. Efficcy of folir ppliction with humic cids vries ccording to the physiologicl sttus of plnts. In our study we found positive effect of humic sustnce sprys on the photosynthesis rte. Photosynthesis in leves of cv. Fetesc Regl nd cv. Riesling Itlin showed the sme trend in response to the folir ppliction of humic cids (Tle 2). The nd tretments induced sttisticlly significnt increse in the photosynthesis rte compred to the controls. The iostimulnt effect of humic cids on photosynthesis ws more pronounced, in oth yers of the study, in cv. FR treted with 40 ml.l -1 nd 50 ml.l -1 humic cids thn in the untreted vines or the plnts treted with 30 ml.l -1. In the cse of the photosynthesis rte for cv. FR, we did not find significnt differences for the plnts treted with 40 ml.l -1 or 50 ml.l -1 humic cid. The photosynthetic response of cv. Riesling Itlin plnts to humic sustnces Tle 1. Effect of humic cid folir ppliction on lef development in grpevine during the 2014 nd 2015 sesons (Vitis vinifer L. cv. Fetesc Regl nd cv. Riesling Itlin) grown in the Stefnesti region, Romni. Cultivr cv. FR cv. RI Tretment Totl lef re (m 2 vine -1 ) Lef fresh weight Lef dry weight Control 5.78 ± 0.08c 5.82 ± 0.19c 2.12 ± ± 0.03c 0.53 ± ± ± 0.48c 5.92 ± 0.16c 2.22 ± ± 0.11c 0.57 ± ± ± ± ± ± ± ± ± ± ± ± ± ,79 ± 0.14 Control 4.28 ± 0.22c 4.29 ± 0.09c 1.98 ± ± 0.11c 0.50 ± ± ± 0.13c 4.52 ± 0.23c 2.08 ± ± 0.08c 0.53 ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.12 Dt presented s men ± stndrd devition. Men vlues followed y the sme letter within columns re not significntly different ccording to Duncn s multiple rnge test (p < 0.05). Control: untreted grpevine; 30 ml L -1 ; HA T2 40 ml L-1 ; HA T3 50 ml L-1 humic cids. 4 Brgnti, Cmpins, Ahed of print, 2018

5 Physiologicl response of grpevine to humic cid ppliction showed the sme trend during oth yers of the experiment. Regrding the influence of humic cids on ssimiltory pigments, these nturl compounds incresed the content of Chl, Chl, nd Cr in the leves (Figure 1). A sttisticlly significnt increse for Chl nd for Cr in cv. FR during the first growing seson ws found for nd compred to or untreted plnts. However, the difference in Chl, Chl nd Cr etween the untreted grpevines nd the plnts treted with of cv. RI nd cv. FR ws not significnt for oth growing sesons. In 2015, the crotenoids content in leves of grpevine treted with humic cids ws significntly higher t the concentrtion of 50 ml.l -1 ( ) thn for nd the control smples. No sttisticl differences in crotenoids pigments were oserved etween the plnts treted with nd untreted grpevines. In the cse of Chl for cv. RI in 2015, we did not find ny sttisticlly significnt difference etween ll the humic cid concentrtions nd the control smples. In the present study, humic cid folir ppliction lso enhnced the lef chlorophyll content, in ccordnce with the results of Sir et l. (2014), who determined higher chlorophyll content in the leves of vines treted with Ascophyllum nodosum L., seweed extrct frequently used in griculture. The seweed extrcts used s iostimulnts in grpevine incresed the chlorophyll content, yields nd erry weight (Sir et l. 2014). Fn et l. (2014) descried tht the folir ppliction of humic cid improved the lef re, net photosynthesis rte nd the chlorophyll content in chrysnthemum compred with those of control plnts. Regrding the results otined Tle 2. Effect of humic cid folir ppliction on photosynthesis rte in leves of grpevine during the 2014 nd 2015 sesons (Vitis vinifer L. cv. Fetesc Regl nd cv. Riesling Itlin) grown in the Stefnesti region, Romni. Photosynthesis rte (µmol CO 2 m -2 s -1 ) cv. FR Photosynthesis rte (µmol CO 2 m -2 s -1 ) cv. RI Tretment Control ± ± 0.43c 8.72 ± 0.35c 8.97 ± 0.32c ± ± ± 0.42c 9.13 ± 0.23c ± ± ± ± ± ± ± ± 0.88 Dt presented s men ± stndrd devition. Men vlues followed y the sme letter within columns re not significntly different ccording to Duncn s multiple rnge test (p < 0.05). Control: untreted grpevine; 30 ml L -1 ; HA T2 40 ml L-1 ; HA T3 50 ml L-1 humic cids c c c c c c c c 0 Chl Chl Cr Chl Chl Cr Chl Chl Cr Chl Chl Cr cv. FR 2014 cv. FR 2015 cv. RI 2014 cv. RI 2015 Control Men vlues followed y the sme letter re not significntly different ccording to Duncn s multiple rnge test (p < 0.05). Brs indicte stndrd devition of men. Control: untreted grpevine; 30 ml L -1 ; 40 ml L -1 ; 50 ml L -1 humic cids. Chl : Chlorophyll in leves (mg g -1 ); Chl : chlorophyll in leves (mg g -1 ); Cr: crotenoids in leves (mg g -1 ). Figure 1. Effect of humic cids folir ppliction on ssimiltory pigments in grpevine leves during 2014 nd 2015 sesons (Vitis vinifer L. cv. Fetesc Regl nd cv. Riesling Itlin). Brgnti, Cmpins, Ahed of print,

6 G.C. Popescu nd M. Popescu for ssimiltory pigments, our outcomes re in line with the findings of Hghighi et l. (2012), who demonstrted tht the totl lef chlorophyll content ws incresed with the folir ppliction with humic cids. Recent studies hve confirmed the hypothesis of direct effect of humic cids on plnt physiology (Hghighi et l. 2014). Humic sustnces seem to positively influence metolic nd signlling pthwys involved in plnt development, y cting directly on specific physiologicl mechnisms (Trevisn et l. 2010). According to Trevisn et l. (2010), humic cids influence plnt development y interfering with the trnscription of genes involved in meristem formtion nd orgniztion, cell cycle, microtuule orgniztion nd cytokinesis. Humic cids ply n importnt role for promoting the mechnism of cell division nd differentition. Cnells et l. (2015) noted tht humic cids incresed ATPse synthesis nd ctivity in root cells. Some uthors reported tht humic cid ioctivity promotes plnt growth y inducing hormone-like ctivities (Clvo et l. 2014; Cnells et l. 2015). Yield nd erry qulity response to folir humic cid ppliction In order to evlute the effects of humic cid folir sprys some quntittive prmeters of grpe production were nlyzed: the recorded vlues re presented in Tle 3 nd Figure 2. The highest yield of grpes for oth cultivrs ws otined in plnts treted with nd the lowest yield ws oserved in nd in the untreted vines (Tle 3). For ll the folir tretments, humic cids in different concentrtion incresed plnt yield. However c cc c c c c c c 100 CW 100 BW 100 BV (ml) CW 100 BW 100 BV (ml) CW 100 BW 100 BV (ml) CW 100 BW 100 BV (ml) cv. FR 2014 cv. FR 2015 cv. RI 2014 cv. RI 2015 Control Men vlues followed y the sme letter re not significntly different ccording to Duncn s multiple rnge test (p < 0.05). Brs indicte stndrd devition of men. Control: untreted grpevine; 30 ml L -1 ; 40 ml L -1 ; 50 ml L -1 humic cids. CW: cluster weight; 100 BW: 100 erry weight; 100 BV: 100 erry volume. Figure 2. Effect of folir ppliction of humic cid on cluster weight, 100 erry weight, erry volume (ml 100 erries -1 ) in grpevine during 2014 nd 2015 sesons (Vitis vinifer L. cv. Fetesc Regl nd cv Riesling Itlin). Tle 3. Effect of humic cids folir ppliction on the yield of grpevine during the 2014 nd 2015 sesons (Vitis vinifer L. cv. Fetesc Regl nd cv. Riesling Itlin) grown in the Stefnesti region, Romni. Yield cv. FR (kg vine -1 ) Yield cv. RI (kg vine -1 ) Tretment Control 2.48 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.16 Dt presented s men ± stndrd devition. Men vlues followed y the sme letter within columns re not significntly different ccording to Duncn s multiple rnge test (p < 0.05). Control: untreted grpevine; 30 ml L -1 ; HA T2 40 ml L-1 ; HA T3 50 ml L-1 humic cids. 6 Brgnti, Cmpins, Ahed of print, 2018

7 Physiologicl response of grpevine to humic cid there were no sttisticl differences etween the plnts treted with nd those treted with. The yield of cv. FR plnts ws higher thn those of cv. RI for oth growing sesons. The results for grpe oenologicl prmeters re shown in Tle 4. The humic cid pplied in concentrtion of 50 ml.l -1 ( 50 ml.l -1 ) induced significnt increse of totl solule solids in grpe nd significnt improvement of the other qulity prmeters (titrtle cidity) when compred to the controls. However, the difference in TSS of cv. RI ws not significnt etween ech of the smples treted with 30 ml.l -1 humic cid ( ) nd the control smples. In the second yer of oservtions we found the sme trend for TTS in cv. FR. Plnts of cv. FR nd cv. RI treted with humic cids t 40 ml.l -1 ( ) nd with 50 ml.l -1 ( ) were sttisticlly different in TTS (Tle 4). In lmost ll the smples, the experimentl results showed tht the humic cids enhnced the TSS of plnts of cv. FR. nd cv. RI, ut they generlly cused decrese of TA. There ws no significnt difference in TA etween tretments with 40 ml.l -1 ( ) nd with 50 ml.l -1 humic cids ( ), with the exception of cv. RI in The results otined for totl solule solids nd titrtle cidity stisfy the qulity stndrds for producing wine with PDO lel in the viticulturl region of Stefnesti. The influence of humic cids on the cluster weight of plnts ws significnt in grpevine treted with nd compred to plnts treted with 30 m.l -1 humic cids or controls (Figure 2). The effect of humic cids on the weight nd volume of erries ws more pronounced in plnts with nd thn with 30 ml.l -1 or in untreted plnts. The quntittive prmeters, expressed y cluster weight, 100 erries weight nd erry volume (ml 100 erries -1 ), were higher in the plnts of cv. FR thn cv. RI for oth growing sesons. The untreted vines hd the lowest cluster weight, erry weight, nd erry volume vlues for the two yers. Among the humic cid tretments, induced the highest verge in cluster weight, erry weight, nd erry volume of cv RI plnts in 2014 or 2015 nd ws found to e significntly different from the others tretments. Two significnt indictors, which reflect the reltionship mong the lef re, yield nd the oenologicl prmeters in grpes, were nlyzed under the influence of folir ppliction with humic cids (Figure 3). Humic cid ppliction in cv FR showed no significnt difference etween tretments in the lef re to yield rtio, while for cv. RI plnts smll ut sttisticlly significnt differences etween tretments were oserved etween untreted plnts nd the ones under tretment. The gretest lef re to yield rtio ws oserved in the tretment without humic cid, while the minimum vlues of this indictor ws seen in the tretment, except in the cse of cvs. FR nd RI in 2014 with minimum rtio registered for the tretment. The highest Brix/TA rtio ws oserved in the plnts from the tretment. The lowest Brix/TA rtio ws found in the controls. By nlyzing the Brix/TA rtio, this study llowed us to oserve significnt differences etween the,, nd tretments. The decrese of lef re to yield rtio in Riesling Itlin nd Fetesc Regl cultivrs likely incresed the efficcy of lef re to increse yield. The Brix/TA rtio showed tht treted vines hd fster ripening thn control ones. Some uthors hve shown humic cids extrcted from vermicompost to e more efficient to enhnce plnt growth nd yield thn other products (Befrozfr et l. 2013). The Tle 4. Effect of humic cid folir ppliction on totl solule solids ( Brix) nd titrtle cidity (g H 2 SO 4 L -1 ) in grpevine during the 2014 nd 2015 sesons (cv. FR; cv. RI). Cultivr cv. FR cv. RI Tretment Totl solule solids ( Brix) Titrtle cidity (g H 2 SO 4 L -1 ) Control ± 0.29d ± 0.25d 5.74 ± ± ± 0.31c ± 0.19c 5.66 ± ± ± ± ± ± ± ± ± ± 0.10 Control ± 0.14c ± 0.27d 6.26 ± 0.10c 6.28 ± ± 0.17c ± 0.06c 6.16 ± 0.17c 6.14 ± ± ± ± ± ± ± ± ± 0.14 Dt presented s men ± stndrd devition. Men vlues followed y the sme letter within columns re not significntly different ccording to Duncn s multiple rnge test (p < 0.05). Control: untreted grpevine; 30 ml L -1 ; HA T2 40 ml L-1 ; HA T3 50 ml L-1 humic cids. Brgnti, Cmpins, Ahed of print,

8 G.C. Popescu nd M. Popescu d c d c c c d c Lef re Brix/TA Lef re Brix/TA Lef re Brix/TA Lef re Brix/TA to yield to yield to yield to yield cv. FR 2014 cv. FR 2015 cv. RI 2014 cv. RI 2015 Control Men vlues followed y the sme letter re not significntly different ccording to Duncn s multiple rnge test (p < 0.05). Brs indicte stndrd devition of men. Control: untreted grpevine; 30 ml L -1 ; 40 ml L -1 ; 50 ml L -1 humic cids. Brix: totl solule solids; TA: titrtle cidity (g H 2 SO 4 L -1 ). Figure 3. Effect of folir ppliction of humic cid on lef re to yield (m 2. kg -1 ) rtio nd Brix/TA rtio in grpevine during 2014 nd 2015 sesons (Vitis vinifer L. cv. Fetesc Regl nd cv Riesling Itlin) ppliction of humic cids t 40 ml.l -1 ( ) nd 50 ml.l -1 ( ) induced significnt increse in weight nd volume of grpe erries in cv. Fetesc Regl grpevine. These results re in greement with dt otined y Ferrr nd Brunetti (2010). In this pper we found tht high chlorophyll content in grpevine leves cn e prtilly responsile for the increse in net photosynthesis. The high lef re nd net photosynthesis likely contriuted to hsten grpe ripening, thus leding to higher TSS content t mturity. Mohmdinei et l. (2015) evluted the impct of folir ppliction t concentrtions of 2.5 mg.l -1 to 7.5 mg.l -1 on yield nd erry ttriutes in grpevine. In line with our findings, they reported tht the influence of humic cids on yield, erry weight nd volume, nd TSS of grpe ws enhnced compred to the untreted vines. The lef re to yield rtio is n indictor tht influences TSS (Kliewer nd Dokoozlin 2005; Filippetti et l. 2015). In the current study, the lef re to yield rtio in Riesling Itlin nd Fetesc Regl cultivrs were influenced y the folir ppliction of humic sustnces derived from vermicompost, resulting in well-lnced grpe production with sufficient level of solule solids. Humic cids ply significnt role for plnt nutrition nd physiologicl sttus s source of nutrients nd iostimulnt. Our experiments demonstrte tht BioHumusSol my provide such dul role, especilly when no fertilizer or other mendments were pplied. CONCLUSION The humic cids spryed t different concentrtions in this study influenced lef development, physiologicl ctivity, yield, nd erry qulity ttriutes of grpevine. Within the experimentl conditions used in this study, we showed tht the humic cids hd positive effect on plnt growth nd fruit qulity when pplied t the preloom nd fruit set phenologicl stges. In our study, the most responsive vriety to the HA tretment ws cv. Riesling Itlin. In this regrd, vrieties responded in different wys to the HA tretments, ut there is similr likely positive effect for ny grpevine vriety. In order to improve the plnt nutritionl nd physiologicl sttus, frmers my use commercil products sed on humic sustnces. For most of the treted smples, humic cids extrcted from vermicompost significntly stimulted yield nd qulity prmeters of the plnts of Fetesc Regl nd Riesling Itlin grpe cultivrs. Results otined in 2015 confirmed the trend oserved in The experimentl results in the present study indicte tht folir ppliction 8 Brgnti, Cmpins, Ahed of print, 2018

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