Europ.J.Hort.Sci., 73 (2). S. 62 68, 2008, ISSN 1611-4426. Verlg Eugen Ulmer KG, Stuttgrt Effects of Summer Pruning on Vegettive Growth, Fruit Qulity nd Crbohydrtes of Regin nd Kordi Sweet Cherry Trees on Gisel 5 V. Usenik, A. Solr, D. Meolic nd F. Štmpr (University of Ljubljn, Biotechnicl Fculty, Agronomy Deprtment, Ljubljn, Sloveni) Summry Five-yer-old sweet cherry trees of Kordi nd Regin were summer pruned in 2003, 2004 nd 2005. Pruning in 2003 consisted of three tretments of heding new shoots (0, 33.3 nd 66.6 % of the length of nnul shoots ws removed), in 2004 of pruning like in 2003 nd by thinning vigorous brnches, nd in 2005 of thinning of vigorous brnches only. Summer pruning positively influenced vegettive growth nd fruit qulity of Kordi nd Regin on Gisel 5 nd hd no negtive effect on the content of soluble crbohydrtes in the dormnt shoots. Pruning to remove some mjor brnches promoted better fruit qulity thn did heding of nnul shoots. Control trees hd similr yield nd yield efficiency s pruned trees but lower fruit weight nd qulity. Trees of Kordi nd Regin on Gisel 5 should be pruned nnully to void the development of blind wood nd to blnce cnopy F:LA for high sweet cherry fruit qulity. Trees of Regin should be pruned more strongly thn those of Kordi. Key words. sweet cherry pruning summer fruit qulity yield efficiency growth Introduction is the most importnt chrcter of sweet cherry (Prunus vium L.) fruit qulity (USENIK et l. 2005). Introducing precocious, vigour-controlling rootstocks, s Gisel 5 (STEHR 2005; USENIK et l. 2006) in sweet cherry production often results in high yields of smll fruits. The reduction of fruit qulity my be consequence of higher rtios of fruit number to lef re (F:LA) (WHITING nd LANG 2004). Poor mngement of high density orchrd system cn provide disstrous results for yields, fruit qulity nd tree longevity (LANG 2005). A reltionship exists between fruit qulity, yield, nd LA in sweet cherry cnopies, prticulrly on dwrfing rootstocks. Blncing cnopy F:LA is criticl for improving sweet cherry fruit qulity on dwrfing rootstocks. Pruning strtegies re being investigted from tht point of view (WHITING nd LANG 2004). Precise shoot pruning is importnt for optimising reltionships between shoot growth, source lef re, current photosynthesis, nnul building of storge reserve nd the ultimte relistion of good yields of high qulity fruit (LANG 2001). Both young nd mture trees on Gisel stocks must be pruned more ggressively thn those on Mzzrd (LANG 2001), but in mny prts of the world where sweet cherries re grown, trees my be severely dmged by bcteril cnker (Pseudomons mors prunorum nd P. syringe). Becuse of this risk, mny sweet cherry growers in Europe perform pruning in summer (FLORE et l. 1996) becuse trees re less likely to become infected (MÜLLER nd STORCK 1991). Shding cn hve profound effect on the vegettive nd reproductive growth of sweet cherry, especilly in high density orchrds (FLORE et l. 1996). Summer pruning reduces shding within the cnopy nd stimultes new shoot growth of pricots (KÜDEN nd SON 2000). Cherries re unique mong deciduous tree fruits becuse of their short period between flowering nd hrvest (ROPER nd KENNEDY 1986). Spur leves lone do not hve the cpcity to support mximum fruit growth in sweet cherry nd must be supplemented by photosynthtes from other sources. During stge III of fruit development, much of the dditionl crbohydrte for fruit growth on 2-yer-old spurs must come from leves on 1-yer-old wood nd from current seson growth (ROPER et l. 1987). Since vegettive vigour cn slow s cropping begins, especilly on precocious rootstocks such s Gisel 5 (LANG 2001), the stimultion of new vegettive growth with precise shoot pruning is needed. Summer pruning cused very little to no regrowth of Sweethert sweet cherry trees on Mzzrd rootstock nd fruit size ws unffected (KAPPEL et l. 1997). Young sweet cherry trees ( Bing on Dmil rootstock) cn be pruned bout 45 dys fter full bloom (DAFB) by heding the shoots to 15 to 20 cm to mximize the benefits of summer pruning on inititing new flowers (GUIMOND et l. 1998). In tril with the cherry rootstocks Prunus vium', CAB 11E, Mxm 14, Gisel 5 nd Edbriz pruning severities were pplied (0, 30, 60 nd 90 % of the new vegettive growth ws removed). Pruning significntly ffected root length nd weight of the rootstocks (GONÇALVES et l. 2003). Delying pruning until fter hrvest cn reduce the subsequent ccumultion of storge
Usenik et l.: Effects of Summer Pruning on Sweet Cherry Trees 63 reserves, thereby reducing the resources vilble for subsequent seson vigour (LANG 2005). There re few dt bout the effect of pruning on vegettive growth nd the reltionship between crop lod nd fruit qulity in sweet cherry production when using stndrd non-precocious, nd especilly when using precocious (e.g., Gisel 5 ) rootstocks. Also, there re no exct dt bout the vegettive chrcteristics nd fruiting hbit of the most importnt sweet cherry cultivrs for middle Europe, Kordi nd Regin. The objective of this reserch ws to study the effects of severity of summer pruning on ccumultion of crbohydrtes in shoots, vegettive nd reproductive growth, fruit qulity nd yield efficiency of the two light-bering sweet cherry cultivrs Kordi nd Regin on Gisel 5 rootstock. Mterils nd Methods Kordi nd Regin sweet cherries on the rootstock Gisel 5, plnted in spring 1999 nd spced 2.5 x 4 m, were trined to Vogel spindle (VOGEL 1994) t Fruit Growing Centre Gcnik (Sloveni). Trees were irrigted with under-tree drippers. Thirty experimentl trees were selected per cultivr on the bsis of uniform vigour (ccording to trunk dimeter). Trees were ssigned to rndomised complete block design of two blocks (orchrd loction) per cultivr nd tree tretments per block. Five trees were selected per tretment. Tretments were pplied to whole trees. Two comprble brnches on two different prts of every tree, 1 to 2 m bove ground level, were selected per tree for mesurements. Stndrd orchrd mngement prctices (irrigtion, fertiliztion, pest control) were followed in ll yers. Pruning tretments Pruning tretments imposed 3 June 2003 (38 DAFB) consisted of control (no pruning, T1), removl of 1 / 3 of the length of ll new shoots, longer thn 20 cm (T2) nd removl of 2 / 3 of the length of ll nnul shoots (T3). Pruning in 2004: pruning tretments in block 1 were imposed in the middle of July 2004 s noted for 2003, pruning in block 2 ws imposed by thinning pruning: i.e., 2 to 3 vigorous brnches per tree were thinned out (bsl dimeter greter thn hlf of the dimeter of the leder). Pruning in 2005 ws imposed in the middle of July, in ll trees by thinning pruning s described for 2004. Vegettive chrcteristics Trunk dimeter t 40 cm bove the ground level ws mesured t the end of dormncy in spring 2003, nd in 2004 nd 2005 during the dormnt period. From trunk dimeter dt trunk cross-sectionl res (TCA) were clculted. Bsl dimeters of two rndomly selected brnches per tree were mesured on 27 April 2004 nd 24 April 2005. On two selected brnches per tree, the result of 2003 pruning ws observed on 5 July 2004: the number of ded shoots, the number of new shoots nd the length of new shoots in July 2004. Ded shoots re ones tht grew in 2003, from which 1 / 3 or 2 / 3 of the length were removed nd died between pruning nd seson 2004. Reproductive chrcteristics per brnch The number of flowers ws counted on selected brnches in 2004 nd 2005. Fruit set ws clculted from the number of flowers nd mture fruits on individul brnches. Flowers nd mture fruits were counted on two brnches per tree. Flowers were counted t the beginning of flowering (27 April 2004 nd 24 April 2005) nd mture fruits t hrvest ( Kordi : 5 July 2004, 23 June 2005 nd 5 July 2006; Regin : 5 July 2004, 5 July 2005 nd 10 July 2006). Fruit number per brnch nd yield per tree were recorded t hrvest ( Kordi : 69 DAFB in 2004 nd 60 DAFB in 2005; Regin 69 DAFB in 2004 nd 72 DAFB in 2005). per brnch ws clculted from the totl fruit mss per brnch nd the number of fruits per brnch. Yield nd fruit qulity per tree Yields per tree were recorded in yers 2004, 2005 nd 2006. From ech tree, men fruit weight ws clculted from representtive smpling of 50 fruits per tree. Yield efficiency (kg cm 2 ) ws clculted using the rtio of ech yer s yield to TCA or using the rtio of cumultive yield of two or three yers to TCA. Crbohydrtes in the brk of dormnt shoots After summer pruning in 2003 nnul shoots were collected t the beginning of dormncy (29 October 2003). Three shoots per tree were smpled. Shoots were nlysed for the content of individul sugrs (glucose, fructose, sucrose) nd sorbitol. Phloem with cmbium ws used nd prepred for nlyses. The content of sugrs ws mesured with High Performnce Liquid Chromtogrphy method (HPLC - Thermo seprtion products, Rivier bech, USA), using n isocrtic method ccording to ŠTURM et l. (1999) on Rezex RCM-monoschride (300 x 7.8 mm) column. Sttistic nlyses Anlyses were conducted with the progrm Sttgrphics Plus 4.0. One-wy ANOVA ws used to nlyse the effect of pruning on vegettive growth nd reproductive prmeters (yield, fruit qulity) mesured per tree. Two-wy ANOVA ws used to nlyse the effect of the fctors cultivr, pruning nd block on vegettive growth nd reproductive prmeters mesured per brnch. Differences between tretments were estimted with LSD test nd Duncn s multiple rnge test (α<0.05). Results nd Discussion Crbohydrtes in dormnt shoots In Kordi nd Regin sweet cherry, both on Gisel 5, the content of glucose, fructose, sucrose nd sorbitol ws nlysed in the brk of dormnt shoots from the preceding growing seson (Fig. 1). Sucrose nd sorbitol hd the highest vlues compred to other soluble crbohydrtes. KELLER nd LOESCHER (1989) showed tht sucrose ws the predominnt soluble crbohydrte during dormncy, but sorbitol dominted during ctive growth of Bing /Mz-
64 Usenik et l.: Effects of Summer Pruning on Sweet Cherry Trees (g/g) glucose 1 fructose sucrose sorbitol totl soluble crbohydrtes b b b 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 bc bc b bc b b b c b b T1 T2 T3 T1 T2 T3 'Kordi' 'Regin' Fig. 1. Effects of summer pruning in 2003 (tretments (1 3) on the content of soluble crbohydrtes in dormnt shoots of Kordi nd Regin sweet cherry on Gisel 5 rootstock. Men seprtion by Duncn s New Multiple Rnge Test (P=0.05). zrd sweet cherry. VEBERIC et l. (2003) showed tht sorbitol reched the highest brk concentrtion t the end of the seson in pple, while the contents of sucrose, glucose nd fructose were lower. Generlly, in the present experiment there were no significnt differences between Kordi nd Regin in the content of glucose, sorbitol nd the sum of crbohydrtes. Kordi hd higher content of fructose nd lower content of sucrose thn Regin. According to pruning tretments glucose nd fructose contents were higher in pruned Kordi shoots ( 1 / 3 = T2, 2 / 3 = T3) compred to control trees (T1). CLAIR-MACZULAJTYS et l. (1994) showed tht fter summer pruning the middle nd upper prts of the trunk of sweet cherry contined the highest concentrtions of strch nd soluble sugrs. None of the dormnt pruning tretments in pple trees ffected combined concentrtions of sorbitol nd glucose nlysed together by REICH (1985). Pruning hd no effect on the content of sorbitol, sucrose, or totl crbohydrtes in either cultivrs s shown in the present experiment (Fig. 1). Pruning did not ffect the content of glucose nd fructose in Regin shoots. In Kordi T2 resulted in more glucose nd fructose nd less sucrose thn in control trees; differences between T3 nd the control were not significnt. Our results re not in greement with the sttement of LANG (2005) tht pruning until fter hrvest cn reduce the subsequent ccumultion of storge reserves. Strch ws shown to be the most common storge mteril by KELLER nd LOESCHER (1989) but ws not mesured in our nlyses. Strch nd soluble sugr concentrtions were quite similr in the lower nd upper prts of the trunk of sweet cherry, the concentrtions of soluble sugrs were Tble 1. Brnch circumference, brnch growth increment 2004 2005 nd the number of heded shoots per brnch of Kordi nd Regin sweet cherry on Gisel 5 rootstock. Vlues in verticl row followed by different letter re significntly different t α<0.05 by Duncn multiple rnge test. Cultivr T* Brnch circumference 2004 (mm) Brnch growth increment (mm) Heded shoots brnch 1 (no.) Brnch 1 Brnch 2 2004 2005 Brnch 1 Brnch 2 Kordi 1 39.3±2.5 42.0±2.0 2.6±0.6 b 0.0±0.0 c 0.0±0.0 c 2 43.8±1.5 42.1±2.0 6.4±1.1 7.9±1.5 9.2±1.3 3 42.9±3.0 40.7±1.3 4.6±1.1 b 8.2±0.6 6.6±0.7 b Regin 1 43.7±2.4 43.4±1.7 5.6±1.0 b 0.0±0.0 c 0.0±0.0 c 2 43.7±2.3 43.9±2.7 5.8±1.1 b 3.1±0.8 b 4.4±0.9 b 3 41.5±2.2 43.9±1.8 6.9±1.4 5.5±0.8 b 7.5±1.5 b *Pruning tretments were imposed 3 June 2003 (38 DAFB) s follows: T1 = control (no pruning), T2 = removl of 1 / 3 of the length of ll current shoots longer thn 20 cm, nd T3 = removl of 2 / 3 of the length of ll current shoots. In mid-july 2004, these were repeted in block I, nd in block 2, pruning ws by thinning of brnches. In mid-july 2005, ll pruning (both blocks) ws by thinning s in block 2 in 2004.
Usenik et l.: Effects of Summer Pruning on Sweet Cherry Trees 65 generlly higher thn those of strch (CLAIR-MACZULAJTYS et l. 1994). Vegettive chrcteristics per brnch There were no differences in bsl dimeters of selected brnches between cultivrs nd tretments. On verge, more nnul shoots were heded per brnch on Kordi thn on Regin (Tble 1). There were no significnt differences in the number of heded shoots per tree between T2 (214) nd T3 (250) in Kordi nd between T2 (94) nd T3 (105) in Regin. Generlly, Kordi responded to pruning with more vigorous regrowth the following seson thn did Regin. Similrly, significnt differences were recorded between Merton Glory nd Vn in their response to summer pruning (WEBSTER nd SHEPHERD 1984). In Kordi, T2 resulted in higher number of new shoots (regrowth in 2004). New shoots lso were longer compred to the control (Tble 2). T3 hd no influence on the number of new shoots, but new shoots were longer compred to the control. In Regin, T2 resulted in similr number of new shoots to the control, but these were longer. T3 hd no influence on the number nd length of new shoots in Regin, compred to the control. Results with Bing / Prunus vium showed tht, independently from the seson nd pruning severity, regrowth ws observed (WILCKENS et l. 1998). Pruning influenced the number of ded shoots (Tble 2). Tretments 2 nd 3 resulted in higher number of died shoots in both cultivrs compred to control. Generlly, the number of died shoots increses with the length of shoot removl lthough differences were not significnt. Our results indicte tht, in sweet cherry trees on precocious rootstock new regrowth must be mnged to promote vigour. This cn be obtined with summer pruning (shoot heding). Leves on 1-yer-old wood nd from current seson growth re essentil for fruit growth on 2-yer-old spurs (ROPER et l. 1987). Lef re (LA) on the typicl spur is only sufficient to support the full growth potentil of single fruit; more hevily-set spurs require supplementl LA from non-fruiting shoots (WHITING nd LANG 2004). Incresed vigour through pruning cn be ccomplished by imposing primry heding cuts, rther thn thinning cuts (LANG 2005). The results of this tril do not confirm the finding of WILCKENS et l. (1998) tht, s the mount of removed wood incresed, the number of regrowth shoots lso incresed. With both cultivrs, T2 (removl of 1 / 3 of the length of ech shoot) in 2003 resulted in higher number of new shoots, which were longer, nd lower number of ded shoots compred to T3. As n rchitecturl rule, the response to pruning vries gretly depending on the site of the cut (LAURI 2005). Vegettive chrcteristics per tree Pruning hd no influence on the trunk growth of Kordi (Tble 3). In Regin summer pruning in 2003 resulted in bout 30 % less trunk growth in 2003 2004. KAPPEL et l. (1997) lso reported tht summer-pruned trees hd smller increments nd their finl TCA ws smller thn tht of the control trees. Genertive chrcteristics per brnch Fruit set nd yield efficiency in 2004 (fter summer pruning in 2003) were higher in Regin thn Kordi but fruit weight ws higher in Kordi (Tble 4). Our results for flower number per brnch were in contrst to those of GUIMOND et l. (1998), who found tht ll summer pruning lengths significntly increse the number of flower buds formed t the bse of the pruned shoots. Number of flowers in 2004 ws similr in ll tretments for Kordi nd Regin with no significnt difference between cultivrs (dt not shown). Pruning in 2003 hd no significnt effect in either cultivr on 2004 fruit set, yield efficiency or fruit weight, mesured per brnch. Though not significnt, with cv. Kordi, T2 resulted in higher fruit set, lower yield efficiency nd the highest verge fruit weight compred to the other two tretments. Fruit weight in T2 nd T3 ws 12 % nd 3.6 % higher, respectively With Regin, T2 resulted in lower fruit set nd yield efficiency compred to control. The verge fruit weight of Regin ws higher but not significnt in pruned trees compred to control trees (19.6 % higher in T2 nd 16.1 % in T3). Tble 2. Effects of summer pruning tretments in 2003 (T1 T3) on the number of new shoots, length of new shoots nd number of ded shoots per brnch of Kordi nd Regin sweet cherry on Gisel 5 rootstock, determined on 5 July 2004. Vlues in verticl row followed by different letter re significntly different t α<0.05 by Duncn multiple rnge test. Cultivr T* New shoots (no.) Length of new shoots (cm) Ded shoots (no.) Brnch 1 Brnch 2 Brnch 1 Brnch 2 Brnch 1 Brnch 2 Kordi 1 3.2±0.3 bc 3.1±0.3 c 10.1±1.0 c 11.5±1.5 d 0.0±0.0 c 0.0±0.0 c 2 4.5±0.4 6.9±0.6 21.1±1.1 18.6±0.9 b 4.0±1.6 b 2.9±0.9 3 2.3±0.3 c 2.5±0.3 c 24.9±1.9 26.6±2.4 5.9±0.6 4.5±0.6 Regin 1 2.5±0.3 b 3.6±0.5 bc 11.2±1.2 c 12.3±1.3 cd 0.0±0.0 c 0.0±0.0 c 2 3.5±0.4 b 4.9±0.6 b 16.2±1.4 b 15.7±1.4 bc 1.0±0.0 b 1.7±0.3 3 3.0±0.3 b 2.7±0.3 c 13.4±1.6 bc 13.0±1.6 cd 3.0±0.4 b 3.5±0.8 *Pruning tretments were imposed 3 June 2003 (38 DAFB) s follows: T1 = control (no pruning), T2 = removl of 1 / 3 of the length of ll current shoots longer thn 20 cm, nd T3 = removl of 2 / 3 of the length of ll current shoots.
66 Usenik et l.: Effects of Summer Pruning on Sweet Cherry Trees The highest 2005 yield nd yield efficiency, nd the lowest fruit weight, in 2005 mesured per brnch, were obtined with Regin compred to Kordi (Tble 4). Pruning hd no influence on those prmeters, except on fruit set of Regin. Fruit set per brnch in T2 trees ws significntly lower compred to T1 nd T3. Lower 2005 fruit set in block 2 cn be the consequence of the strong thinning pruning in 2004 which hve resulted in the reduction of storge reserves vilble for the next seson (LANG 2005). Although different types of pruning were imposed in 2004, similr fruit weights mesured per brnch indicte tht the F/LA in the brnch hd not been chnged. Our results indicte tht every brnch cts s n utonomous unit within the crown. Yield nd fruit qulity per tree Yields in 2004, 2005 nd 2006 were sub-optiml, especilly with Kordi. This my hve been the consequence of locl climtic conditions nd the sensitivity of Kordi to low tempertures during flowering. is one of the most importnt prmeters of fruit qulity, which in our tril depended on the genotype s discussed by GONÇALVES et l. (2006), crop lod, picking time nd lso pruning tretments. Yield efficiency in 2004 of control trees of Regin (0.31 kg cm 2 TCA) ws twice tht of Kordi (0.15 kg cm 2 TCA) (Tble 3). Pruning in 2003 hd no significnt influence on yield, fruit weight nd yield efficiency of Kordi in 2004. In spite of this insignificnce, we cn not overlook tht verge yield nd fruit weight of pruned Kordi ws higher thn trees without pruning. Pruning of Regin in 2003 resulted in higher 2004 yields in T2 nd lower, but not significnt, yields in T3. Pruning hd no influence on Regin fruit weight in 2004. Averge fruit weight in T2 trees ws similr to control trees, but ws lower in T3. With T3, lrger mount of shoots, including vigorous brnches, were removed, which could hve reduced the resources vilble for subsequent seson vigour s discussed by LANG (2005). Tble 3. Effects of summer pruning tretments (T1 T3) on trunk growth 2003 2004, yield, fruit weight nd yield efficiency in 2004, mesured per tree, of Kordi nd Regin sweet cherry on Gisel 5 rootstock. Vlues in verticl row followed by different letter re significntly different t α<0.05 by Duncn multiple rnge test. Cultivr T* Trunk growth Yield (mm) (kg tree 1 ) 2003 2004 2004 Yield efficiency tree 1 Kordi 1 27.8±2.7 b 5.9±1.1 b 8.14±0.3 0.15±0.02 b 2 29.3±3.9 b 7.3±0.5 b 8.40±0.3 0.11±0.01 b 3 27.4±3.2 b 7.3±0.5 b 8.24±0.2 0.15±0.02 b Regin 1 44.5±5.0 6.5±1.1 b 7.42±0.5 b 0.31±0.04 2 30.4±4.9 b 11.2±1.3 7.64±0.3 b 0.36±0.06 3 31.0±4.4 b 5.9±0.8 b 6.76±0.4 b 0.28±0.04 *Pruning tretments were imposed 3 June 2003 (38 DAFB) s follows: T1 = control (no pruning), T2 = removl of 1 / 3 of the length of ll current shoots longer thn 20 cm, nd T3 = removl of 2 / 3 of the length of ll current shoots. Tble 4. Effects of summer pruning tretments (T1 T3) on yield efficiency, fruit set nd fruit weight in 2004 nd 2005, mesured per brnch, of Kordi nd Regin sweet cherry on Gisel 5 rootstock. Vlues in verticl row followed by different letter re significntly different t α<0.05 by Duncn multiple rnge test. Cultivr T* Yield efficiency brnch 1 Fruit set (%) Yield efficiency brnch 1 Fruit set (%) 2004 2005 Kordi 1 0.74±0.19 b 4.1±0.9 c 8.3±0.4 0.85±0.14 b 9.8±1.5 c 8.2±0.3 2 0.64±0.09 b 5.2±0.7 c 9.3±0.7 0.67±0.07 b 9.7±1.8 c 8.1±0.3 3 0.78±0.18 b 5.1±0.7 c 8.6±0.6 0.83±0.13 b 10.2±0.8 c 8.4±0.5 Regin 1 2.09±0.15 16.5±1.2 b 5.6±0.2 b 1.95±0.21 36.0±4.1 6.3±0.3 b 2 1.92±0.13 13.8±1.5 b 6.7±0.3 b 1.93±0.21 26.5±2.9 b 6.3±0.4 b 3 2.04±0.19 18.3±1.8 6.5±0.5 b 1.85±0.20 33.6±3.5 b 5.9±0.4 b *Pruning tretments were imposed 3 June 2003 (38 DAFB) s follows: T1 = control (no pruning), T2 = removl of 1 / 3 of the length of ll current shoots longer thn 20 cm, nd T3 = removl of 2 / 3 of the length of ll current shoots. In mid-july 2004, these were repeted in block I, nd in block 2, pruning ws by thinning of brnches.
Usenik et l.: Effects of Summer Pruning on Sweet Cherry Trees 67 Tble 5. Effects of summer pruning tretments (T1 T3) on yield, fruit weight nd yield efficiency of Kordi nd Regin sweet cherry on Gisel 5 rootstock, mesured per tree in different yers. Vlues in verticl row followed by different letter re significntly different t α<0.05 by Duncn multiple rnge test. Cultivr T* Yield (kg tree 1 ) Yield efficiency/tree Block 1 Block 2 Block 1 Block 2 Block 1 Block 2 2005 2005 2004 2005 Kordi 1 10.4±0.9 cd 5.6±0.4 g 8.4±0.2 8.7±0.1ef 0.31±0.03 cd 0.13±0.01 f 2 7.5±0.3 d 7.3±0.9 fg 7.7±0.6 bc 9.8±0.7 e 0.17±0.01 d 0.17±0.02 f 3 8.0±1.2 d 9.8±1.0 fg 7.9±0.3 b 8.6±0.2 ef 0.16±0.02 d 0.29±0.02 ef Regin 1 17.8±3.1 b 16.8±2.7 e 6.8±0.4 bc 8.0±0.7 f 0.55±0.13 b 0.45±0.06 e 2 27.6±2.7 12.6±3.2 ef 6.3±0.1 cd 8.7±0.6 ef 0.73±0.09 0.38±0.10 e 3 15.7±3.2 bc 16.7±1.8 e 5.3±0.4 d 8.4±0.3 f 0.49±0.09 bc 0.44±0.07 e 2006 2006 2004 2006 Kordi 1 8.1±1.7 b 4.5±0.7 b 8.6±0.1 c 9.6±0.4 fg 0.43±0.02 bc 0.19±0.02 b 2 4.1±0.2 cd 7.1±1.6 b 8.2±0.5 c 9.3±0.7 g 0.22±0.01 c 0.24±0.02 b 3 2.4±0.5 d 10.3±1.1 8.7±0.4 bc 9.1±0.2 g 0.19±0.03 c 0.45±0.03 Regin 1 7.0±1.2 bc 7.6±0.8 b 9.7±0.4 b 9.8±0.5 fg 0.67±0.16 b 0.55±0.05 2 11.9±0.7 8.4±1.9 b 9.3±0.3 bc 10.6±0.3 ef 0.89±0.09 0.51±0.12 3 5.4±1.0 bc 6.2±1.3 b 9.8±0.4 11.2±0.1 e 0.58±0.11 b 0.52±0.08 *Pruning tretments were imposed 3 June 2003 (38 DAFB) s follows: T1 = control (no pruning), T2 = removl of 1 / 3 of the length of ll current shoots longer thn 20 cm, nd T3 = removl of 2 / 3 of the length of ll current shoots. In mid-july 2004, these were repeted in block I, nd in block 2, pruning ws by thinning of brnches. In mid-july 2005, ll pruning (both blocks) ws by thinning s in block 2 in 2004. Pruning in 2004 resulted in different yields between blocks of Kordi nd Regin in 2005 (Tble 5). Pruning tretments in block 1 were the sme in 2004 s in 2003. Trees in block 2 were pruned in 2004 strongly with thinning cuts. Generlly, different pruning in blocks ffected yield nd fruit weight of both cultivrs. Strong thinning pruning in block 2 promoted higher fruit weight of both cultivrs, especilly with Regin, nd in some tretments lso lower yields. Pruning influenced yield nd fruit weight of Kordi lso in 2006 (Tble 5), being higher in block 2 thn block 1, except for the control trees (T1). Yield in 2006 of Regin ws similr in both blocks, but pruning influenced higher Regin fruit weight in block 2. Comprison of 2004 2006 yield efficiencies for Kordi nd Regin reveled: no significnt differences between blocks 1 nd 2. Pruning in block 2 resulted in lower yield efficiency in T1 nd higher yield efficiency in T3 of Kordi compred to block 1 nd with Regin, lower yield efficiency in block 2. Our results prtly confirm the sttement of WOLFRAM (1999) tht non-pruned trees showed higher yield but lower fruit weight compred to pruned trees. Non-pruned trees in our reserch showed similr yield nd yield efficiency s pruned trees but lower fruit weight/lower fruit qulity. In non-pruned trees of Kordi nd Regin the proportion of blind wood (non-productive wood) incresed every yer due to shding of the interior prt of the tree crown. Pruning strtegies re being investigted tht focus on nnul blncing of crop lod with lef re (WHITING nd LANG 2004). Conclusions Our dt suggest tht there re differences between Kordi nd Regin in tree vigour nd fruiting hbit even though both re generlly strong-growing nd light-bering cultivrs. Kordi is more vigorous nd less productive with higher fruit weight thn Regin under the conditions of this study. These differences influenced the response of these two cultivrs to pruning tretments. Pruning hd no influence on soluble crbohydrtes in dormnt shoots. There were no differences between Kordi nd Regin in the contents of soluble crbohydrtes. Our dt suggest tht summer pruning positively influences vegettive growth nd genertive development of sweet cherries on precocious rootstocks. Pruning to remove some mjor brnches fter hrvest hd greter influence on fruit weight thn summer heding of current seson- shoots to increse light penetrtion into the cnopy. Pruned trees hve lrger proportion of new shoots, which re necessry for high qulity fruits, nd smller shded proportion of the crown, which improves photosynthesis nd reduces blind, unproductive wood. Becuse of the influence of shding nd lso cultivr chrcteristics the blind wood effect, common on sour cherry vrieties, lso is concern in high density sweet cherry orchrds. Under conditions of high pressure of Pseudomons infection, pruning sweet cherry trees fter hrvest (summer pruning) is convenient for mnging vigour, crop lod nd fruit qulity. Annul pruning of sweet cherry trees on
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