Towards Grower-friendly Apple Crop Thinning by Tree Shading

Transcription

1 314 Towrs Grower-frienly Apple Crop Thinning y Tree A. Wimer 1, K. Kockerols 1, S. Schwn 1, W. Stler 1 n L. Bertschinger 1 Astrct Light mngement with shing nets, which reuce sunlight y 74%, might e n lterntive to chemicls commonly use for on pple trees. To stuy the effect of shing on crop lo n fruit qulity, trils were conucte in fiel experiments with the cultivrs Golen Delicious n Elstr in 6. Trees were either covere 25 ys fter full loom (DAFB) with net uring three ys, or until the pek of fruit fll, oserve fter seven ys shing. Iel time length for optiml crop yiel ws seven ys shing for Elstr n three ys shing for Golen Delicious. Alternte ering coul e ecrese s flower initition counts the following yer showe. In oth experiments, inner qulity of fruit such s sugr n firmness showe goo vlues t optiml shing urtion compre with chemicl + hn. In 7, secon fiel tril ws conucte with cultivrs Golen Delicious n Topz to stuy the time perio for shing in further etil. ws one for three ys t 19, 26 n 33 DAFB using two net types (three- n two-meter-net with, covering the trees entirely or only own to cm ove groun). For Golen Delicious, shing fter 19 n 26 ys reuce fruits per flower cluster to the sme extent s with chemicl + hn. There ws no ifference etween the two net types. For Topz, shing fter 19 ys showe the est results. Regring inner qulity of oth cultivrs, only sugr content for Golen Delicious coul e significntly improve fter 19 n 26 ys shing. Further nlyses re still uner wy (e.g. for ciity). This stuy is prt of n effort for incresing Europen consumption with fruit from sustinle prouction systems, the ISAFRUIT-EU-project. Keywors: Thinning, net, Flower initition, Crop lo, Fruit qulity Introuction Apple trees hve to e thinne ech yer in orer to ensure constnt crop yiel n high fruit qulity for the mrket. But, the optiml effect of chemicl thinners is very epenent on wether conitions efore, uring n fter ppliction. Therefore, the effect of gent ppliction might lck the necessry crop lo reuction n cn le to n unstisfctory result (Stler & Wimer, 3). Currently, in orgnic pple prouction, there is no gent ville for fruit. Crops hve to e thinne out y hn or mechniclly with mchine (B & Lfer, 5). However, in prticulr orchrs n frm situtions, this oes often not le to stisfctory results. Overll, hn is the most ccurte wy to just crop lo ut it is lso very time-consuming. Byers et l. (1985) foun out tht shing efore June rop enhnces pple fruit scission. In shing trils crrie out y Berüter n Droz (1991), McArtney et l. (4) n Stler et l. (5), time n impct of shing on fruit scission ws further investigte. To etermine, if shing cn e use s strtegy in frmers orchrs, itionl trils with shing of pple trees were conucte s prt of the Europen project ISAFRUIT (Incresing fruit consumption through trns-isciplinry pproch elivering high qulity prouce from environmentlly frienly, sustinle prouction methos). 1 Agroscope Chngins-Wäenswil Reserch Sttion ACW, 882 Wäenswil, Switzerln, e-mil: lert.wimer@cw.min.ch

2 315 Mteril n Methos Trils in 6: The im of the trils in 6 ws to stuy the effect of shing length on crop lo n fruit qulity of Elstr n Golen D. Tretments on 9-yer-ol pple trees: 1) ; 2) Crop lo juste y chemicls ( oth cultivrs / Ethephon Elstr only) n hn (positive control); 3) (74% of full sun) 25 DAFB uring three ys n 4) (74% of full sun) 25 DAFB until the pek in fruit fll ws registere. nets were fixe y hn on wire just ove the tree top. Temperture, humiity, crop lo n crop qulity were investigte. Counting of fruitlets ws ccomplishe fter fruit rop on 3 r July 6. Elstr ws hrveste on 12 th Septemer 6, Golen D. on 2 n Octoer 6. Trils in 7: The im of the trils in 7 ws to stuy the effect of ifferent shing urtions (19, 26 n 33 DAFB) n ifferent shing tretments (2m n 3m net with) on crop lo n fruit qulity of Topz n Golen D.. Trees were 2.m high. ws prouce y net which reuces sunlight y 74%. The trees were in its 1-th lef. Tretments: 1) ; 2) Chemicl tretment ( ppm) + Hn ; 3) Chemicl tretment ( ppm); 4) 19 DAFB (Golen D.: Fruit imeter 12-13mm) for 3 ys, 2m-net with; 5) 19 DAFB for 3 ys, 3m-net with; 6) 26 DAFB (Golen D.: Fruit imeter 16-18mm) for 3 ys, 2m-net with; 7) 26 DAFB for 3 ys, 3m-net with; 8) 33 DAFB (Golen D.: Fruit imeter 22-24mm) for 3 ys, 2m-net with; 9) 33 DAFB for 3 ys, 3m-net with. Recors were tken of the photosynthesis rte elow net, of crop lo n of crop qulity. Counts of flower clusters were ccomplishe on 2 th April n 4 th My 7. Golen D. ws hrveste on 2 th Septemer 7, Topz on 2 th n 21 st Septemer 7. Results Trils in 6: Optiml crop lo ws chieve fter 3 ys shing for Golen D. (Fig. 1). For Elstr, 7 ys shing resulte in optiml. Cultivr Elstr Golen Fruits per Flower Cluster c Chemicl + Hn 3 ys 7 ys Figure 1: Numer of fruits per flower clusters of Golen D. n Elstr for ifferent tretments. Griel test, =,5; ifferent letters for the sme cultivr show significnt ifferences.

3 316 Trils Fruits/ Flower cluster 2 cluster Flower Fruits/ 2 NAAM + Hn c c 22 19, 2m 19, 3m c 26, 2m c 26, 3m , 3m Fruits/ Flower Cluster Hn 7 c c 19, 2m 19, 3m c 26, 2m c 26, 3m 29 33, 3m 12 NAAM + Hn 19, 2m 19, 3m 26, 2m 26, 3m 33, 3m 3 Cluster Fruits/ Flower 2 7 c c c c 29 + Hn 19, 2m 19, 3m 26, 2m 26, 3m 33, 3m Figure 2: Numer of fruits per flower clusters of Golen D. (left) n Topz (right) for ifferent tretments. Tmhne test, =,5; ifferent letters show significnt ifferences.

4 317 Tle 1: Solule solis, firmness, crop yiel, fruit weight of Golen D., Elstr for ifferent tretments. Cultivr Tretment Solule solis Firmness Crop yiel Fruit Weight (g) ( Brix) (kg/m 2 ) (kg) Golen D Golen D. Chem.+Hn Golen D Golen D Elstr Elstr Chem.+Hn Elstr Elstr Regring inner qulity, 3 ys shing showe goo results in solule soli content n firmness for Golen D. (Tle 1). For Elstr, 7 ys shing le to goo results in solule soli content n fruit weight s compre to tretment 2. For Golen D., three y shing t 19, 26 DAFB (2 n 3m-net) n 33 DAFB (3m-net) showe significnt ifferences compre to the control (Fig. 2). For Topz, only three y shing t 19 DAFB resulte in significnt ifference. Tle 2: Solule solis, firmness, crop yiel n fruit weight of Golen D. for ifferent tretments. Tretment S.solis( Brix) Firmness (kg/m 2 ) Crop yiel (kg) Fruit weight (g) Hn , 2m , 3m , 2m , 3m , 3m Regring inner qulity for Golen D., ll shing tretments le to goo results in solule soli content (T. 2). For Topz, significnt ifference in solule soli content is shown only fter 19 ys shing compre to the control (T. 3). For oth cultivrs, there is no significnt ifference in firmness. Tle 3: Solule solis, firmness, crop yiel n fruit weight of Topz for ifferent tretments. Tretment S.solis( Brix) Firmness (kg/m 2 ) Crop yiel (kg) Fruit weight (g) Hn , 2m , 3m , 2m , 3m , 3m

5 318 Discussion Our shing trils conucte in 6 n 7 showe goo potentil for n lterntive to chemicl. The crop lo cn e regulte to the necessry extent, the chieve fruit qulity is cceptle n flower counts in 6 n 7 on the she pple trees showe tht lternte ering cn e ecrese y this metho. Cultivrs respon ifferently to the length of shing. However, trils in 7 hve shown tht there is time perio uring which the tree response to shing is cceptle, llowing therefore some flexiility in pplying the shing. Results otine uring the recent yers emonstrte tht the response of the metho to ifferent yers (meteorologicl conitions) seems to e surprisingly low (t not shown) which woul llow for the evelopment of roust, stnrize methos. Prcticility of the metho in frmers orchrs hs to e improve, however. By using the sme nets severl times for cultivr specific shing in ifferent orchrs, mteril costs coul proly e reuce. In some trils, no significnt ifferences were oserve etween net with 2m n 3m-with. By using the 2m-with net, costs my lso e reuce. Net instlltion is still too costly n time-consuming, therefore esy to hnle n chep methos must e evelope. References B, G. & Lfer, G. (5). Kernost. Leopolsorf, Austri: Österreichischer Agrrverlg Druckun Verlgs-GmH. Berüter, J. & Droz, P. (1991). Stuies on locting the signl for fruit scission in the pple tree. Scienti Horticulture 46: Byers, R.E., Lyons, C.G., Yoer, K.S., Bren, J.A., Young, R.W (1985). Pech n pple y shing n photosynthetic inhiition. Journl of Horticulturl Science 6 (4): McArtney, S., White, M. Ltter, I., Cmpell, J. (4). Iniviul n comine effects of shing n chemicls on scission n ry-mtter ccumultion of Royl Gl pple fruit. Journl of Horticulturl Science & Biotechnology 79 (3): Stler, W. & Wimer, A. (3). Einfluss von Blühverluf un Witterung uf ie chemische Ausünnung. Schweizerische Zeitschrift für Ost- un Weinu (SZOW) Wäenswil 5: Stler, W., Wimer, A., Doleg, E., Schffner, M., Bertschinger, L. (5). Fruchtusünnung urch Beschttung er Apfeläume eine Methoe mit Zukunft? Schweizerische Zeitschrift für Ost- un Weinu (SZOW) Wäenswil 1: 1-13.