CHARACTERIZATION OF HASS AVOCADO PROLEPTIC AND SYLLEPTIC SHOOT PROPORTION IN VALPARAISO REGION, CHILE

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1 Proceedings VI World Avocdo Congress (Acts VI Congreso Mundil del Agucte) Viñ Del Mr, Chile Nov ISBN No CHARACTERIZATION OF HASS AVOCADO PROLEPTIC AND SYLLEPTIC SHOOT PROPORTION IN VALPARAISO REGION, CHILE J. E. Slvo 1 nd J. P.Mrtínez 1 1 : Instituto de Investigciones Agropecuris, Investigción y Desrrollo. Chorrillos 86, L Cruz, Region of Vlpríso, Chile. e-mil: jslvo@ini.cl Proleptic nd sylleptic shoot development ws studied to chrcterize cnopy rchitecture of Hss vocdo (Perse mericn Mill.) in two provinces of Chile. Syllepsis nd prolepsis rtes t orchrds with different ges were evluted in Petorc nd Quillot provinces in seson. Forty trees were rndomly selected to ech orchrd to this study. Numer of rnches, whose min shoots were proleptic or sylleptic types, ws evluted. Only rnches tht were ccessile round the tree elow 2 m high were considered. In generl, it ws oserved tht Quillot nd Petorc disply sylleptic rtes lower thn proleptic, nd tht there re differences in oth shoot type rtio etween these provinces s well. Moreover, it ws oserved tht prolepsis rtes increse t older ge rnge. It ws concluded tht proleptic nd sylleptic shoot proportion is useful prmeter to show differences mong vocdo orchrds in this region s effect of ge nd loction of the orchrd. Further reserch is required to know how gronomic mngement my ffect such differences. CARACTERIZACIÓN DE LA PROPORCIÓN DE BROTES PROLÉPTICOS Y SILÉPTICOS DEL PALTO HASS EN LA REGIÓN DE VALPARAÍSO EN CHILE J.E. Slvo 1 y J.P. Mrtínez 1 1 Instituto de Investigciones Agropecuris, Investigción y Desrrollo, Chorrillos 86, L Cruz, V Región, Chile, teléfono: Correo electrónico: jslvo@ini.cl Se estudió el desrrollo de rotes prolépticos y silépticos pr crcterizr l rquitectur del dosel del plto Hss (Perse mericn Mill.) en dos provincis en Chile. Se evluron los porcentjes de silepsis y prolepsis en huertos de distints eddes en ls provincis de Quillot y Petorc en l tempord Curent ároles fueron signdos l zr cd huerto en este estudio. Se evluó el número de rms cuyo rote centrl er de tipo proléptico o siléptico. Sólo se consideró rms ccesiles lrededor del árol un ltur no superior 2 m. En generl, se oservó que Quillot y Petorc presentn un menor porcentje de silepsis que de prolepsis, y que tmién existen diferencis en el porcentje de mos tipos de rotes entre ests provincis. Además, se oservó que el porcentje de prolepsis se incrementó con l myor edd del huerto. Se concluye que l proporción de rotes prolépticos y silépticos es un prámetro útil pr mostrr diferencis entre huertos de plto en est región como efecto de l edd y uicción del huerto. Más investigciones son requerids pr conocer cómo el mnejo gronómico puede fectr tles diferencis. 1

2 INTRODUCTION Avocdo (Perse mericn Mill.) disply proleptic nd sylleptic shoot development (Hlle, 1978). Proleptic shoots develop from dormnt uds on one min shoot, nd sylleptic shoots develop on nother min shoot which do not hve yet dormnt uds. As result proleptic shoot development occurs in two time steps: one for min shoot development nd one for new proleptic shoot development. In contrst, sylleptic shoot development occurs simultneously with its min shoot development (Hlle, 1978). Avocdo proleptic nd sylleptic rtios chnge mong loclities (Thorp nd Sedgley, 1993). However, there is not yet informtion out sylleptic nd proleptic shoot development of Hss Avocdo in Chile. Therefore this study hs the ojective to chrcterize Hss vocdo proleptic nd sylleptic rtios in two provinces of Vlpriso region in Chile. MATERIALS AND METHODS Study ws done on thirteen Hss vocdo orchrds in Quillot nd Petorc provinces. Orchrds were locted etween 32.4 o S 71.9 o W nd 32.9 o S 71.2 o W geogrphic positions, nd they were seprted in three ge groups: three to five yers old, six to ten yers old, nd eleven or more yers old. Proleptic nd sylleptic module percentge ws evluted in forty rndomly ssigned trees in ech orchrd. Module nme descries min shoot rnch development type, nd this module my include dditionl proleptic or sylleptic shoots. Mesurements were done in August, Septemer nd Novemer of 2006 yer, this period mtch with spring seson in south hemisphere. Modules tht were ccessile round the tree etween 1 to 2 m height were counted wlking with one meter steps round the tree. Dt ws nlyzed with two fctor fctoril design, in which ge min effect, loction min effect nd interction effect were simultneously evluted. Temperture (ºC) nd reltive humidity (%) ws registered ech five minutes long 2006 yer in four representtive points with dt loggers HOBO H nd softwre Boxcr Pro. Dt were nlyzed with Generl Liner Model procedures (GLM) of the SAS sttisticl progrm (SAS Inst., Inc., Cry, N.C.) to test orchrds ge nd loction effects on sylleptic nd proleptic vocdo shoot development. Duncn men seprtion procedure ws done t 0.05 proility level. RESULTS Temperture nd reltive humidity. Annul verge temperture ws 15 ºC on 2006 yer, with n solute mximum of 37 ºC nd n solute minimum of -1 ºC. Besides, nnul reltive humidity verge ws 78 %. It ws not detected significnt differences on verge temperture y month mong four evlution points (Figure 1). However, verge minimum temperture y month ws 3.97 ºC in Petorc nd 5.51 ºC in Quillot, which re different t proility level of Proleptic nd sylleptic shoot development. Dt show tht proleptic shoot development differences etween Petorc (60.7%) nd Quillot (71.2 %) provinces re very significnt (P vlue ). Results lso point out tht sylleptic shoot development in younger orchrds (51.4%) is igger thn sylleptic shoot development in older orchrds (22.93%). Consequently proleptic shoot development increses s soon orchrd ecome old. 2

3 However, significnt interction etween ge nd loction fctors ws detected (P vlue ), so ge effect is not the sme t different loctions (Tle 1). DISCUSSION AND CONCLUSION Proleptic shoots rtio is higher thn sylleptic shoot rtio in centrl zone of Chile. Besides, orchrd ge nd loction ffect proleptic nd sylleptic module development. However, ge effect is not the sme in oth provinces due significnt interction etween oth fctors. This study show tht younger orchrds disply more mount of sylleptic development, then s orchrd ge the mount of proleptic development increses. This tendency ws shown in Petorc nd Quillot, ut response ws different for oth loclities. Proleptic development in Quillot is igger thn proleptic development in Petorc t younger orchrds, s soon orchrds ecome old such differences decrese, nd differences re not detected t more thn ten yers old orchrds. This work shows tht proleptic shoot development is igger thn sylleptic shoot development in Vlpriso region (32.7ºS 71.6ºW). Thorp dt (Thorp nd Sedgley, 1993) for younger vocdo trees in Melny (26.51ºS ºE) nd dt for dult orchrds in Somis (34.17ºN ºW) t Cliforni lso show this development pttern (unpulished dt). Climte of oth provinces were study to explin proleptic nd sylleptic development differences. However, temperture nd reltive humidity nlyses did not show differences in north south trnsect of evlute zone in 2006 yer. There were not differences for nnul verge temperture or for nnul verge reltive humidity mesured t oth provinces. However, it ws possile to detect differences on minimum temperture y month. Sylleptic shoot development for Petorc ws igger thn sylleptic shoot development for Quillot just t young trees, nd minimum month verge temperture on Petorc ws 1ºC lower thn minimum month verge temperture on Quillot. Thorp lso show tht sylleptic shoot development is igger thn proleptic shoot development on young trees in Mc Lren vlley (32,12ºS 138,32ºE) (Thorp nd Sedgley, 1993). Annul verge temperture in this plce is lower thn nnul verge temperture in Vlpríso, Somis nd Melny on out 6ºC. However, to ssign role for cold temperture to explin more sylleptic developmentl on young trees is controversil, ecuse prolepsis is ssocited to ud pre-formtion, which occurs on cold climtes, nd syllepsis develops new lterl shoots without ud pre-formtion. Besides, some species of Cinnmomun genus, which elong to Lurcee fmily together with Perse genus, disply sylleptic nd proleptic shoot development s well. Nitt nd Osw show tht proleptic shoot development on Cinnmomun genus increses t igger ltitude, nd they explin tht the mount of ville energy for photosynthesis is lower t igger ltitude (Nitt nd Ohsw, 2001). Despite we did not mesure energy vilility; our dt re consistent with ltitude effect on proleptic nd sylleptic shoot development of young Hss vocdo It is concluded tht orchrd ge nd loction influence vocdo shoot development. This pproch is useful to investigtive vocdo orchrd sttus t different ges nd to evlute its premture ging. More reserch is required to determinte gronomic mngement useful to chnge these developmentl ptterns. 3

4 LITERATURE CITED Hllé, F., R.A. Oldelmn, nd P.B. Tomlinson Tropicl trees nd forest - n rchitecturl nlisis. Springer, Berlin, pp.441 Nitt, I. nd M. Ohsw Geogrphicl trnsition of sylleptic/proleptic rnching in three Cinnmomum species with different ud types. Annls of Botny 87, Thorp, T.G. nd M. Sedgley Architecturl nlysis of tree form in rnge of vocdo cultivrs. Scienti Horticulture 53, ACKNOWLEDDGEMENT This puliction is the result of reserch sponsored y INNOVA CHILE with funds from CORFO, under project Aumento de l producción de plts medinte el diseño de un nuevo sistem de pod sdo en el estudio rquitectónico y fisiológico de dos tipos de rotes. We lso grtefully cknowledge to persons tht show wreness llowing us to collect dt in Quillot nd Petorc provinces. Tle 1. Proleptic (PSM) nd Sylleptic (SSM) Shoot Module numer in Hss vocdo trees in commercil orchrds in Petorc nd Quillot provinces of Vlpriso region. Petorc Quillot PSM SSM PSM SSM Age (%) SE (%) SE (%) SE (%)z SE 3-5 yers old 31,2 2,3 68,8 2,3 65,9 1,3 34,1 1,3 c 6-10 yers 68 1,3 32 1,3 68,3 1,1 31,7 1,1 old > 10 yers old P vlue z 75,6 c 1,1 24,5 1,1 79,5 1,2 20,6 1,2 z Significnt differences mong ge fctor (P vlue 0.05) 4

5 Averge temperture (º C) Quillot Petorc 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Time (months) Figure 1. Averge tempertures of 2006 yer in Quillot nd Petorc provinces. 5