Deficit irrigation and canopy management practices to improve water use efficiency and profitability of wine grapes

Simple item page
dc.contributor.advisorHoffman, Josias Eduarden_ZA
dc.contributor.advisorMyburgh, Philipus Albertusen_ZA
dc.contributor.authorLategan, Eugene Lourensen_ZA
dc.contributor.otherStellenbosch University. Faculty of Agrisciences. Dept. of Soil Science.en_ZA
dc.date.accessioned2024-03-05T10:55:09Z
dc.date.accessioned2024-04-26T09:58:12Z
dc.date.available2024-03-05T10:55:09Z
dc.date.available2024-04-26T09:58:12Z
dc.date.issued2024-03
dc.descriptionThesis (PhDAgric)--Stellenbosch University, 2024. en_ZA
dc.description.abstractENGLISH ABSTRACT: Grapevines irrigated at low plant available water (PAW) depletion levels required more than double the irrigation volumes compared to those irrigated at high depletion levels. The accelerated sugar accumulation of sprawling grapevine canopies resulted in earlier harvest dates, reducing pre-harvest irrigation requirements. Different canopy manipulations did not affect total leaf area (LA) per grapevine within an irrigation strategy, but negatively affected LA as less water was applied. Non-suckered grapevines produced more shoots and more vigorous shoot growth, while non-suckered vertical shoot positioned (VSP) grapevines tended to produce lower cane mass. The LA distribution provides a good indication of canopy orientation, and non-destructive measurements of primary and secondary shoots can estimate winter pruned cane mass. This would allow viticulturists, producers, or irrigation consultants to estimate the maximum cane mass and use the VINET© model to predict grapevine water requirements in real-time throughout the season, as the LA is estimated using cane mass. Grapevines with sprawling canopies had lower mid-day leaf water (ΨL) and stem water (Ψs) potentials compared to those with VSP canopies. Grapevines experiencing severe water constraints ripened more rapidly than those without or with medium water constraints. Low frequency irrigation increased water constraints compared to high frequency irrigation. Diurnal ΨL cycles showed that grapevines with sprawling canopies had lower ΨL after 18:00 and throughout the night, suggesting that their water status could not recover as fast as VSP grapevines. High irrigation frequencies led to higher grapevine row evapotranspiration (ETGR) losses, with losses from sprawling grapevines, particularly those irrigated at ca. 30% plant available water (PAW) depletion, being higher in January and February than those with VSP canopies. Seasonal full surface evapotranspiration was more sensitive to irrigation frequency than to canopy manipulations. Grapevines irrigated at ca. 30% PAW depletion had higher mean full surface crop coefficient (Kc) values compared to other strategies, with those irrigated at ca. 90% PAW depletion having the lowest Kc values. The mean peak Kc was generally obtained in February for grapevines irrigated at frequencies, while the lowest Kc was found during the same period for low frequency irrigation applications. The fraction of soil wetted during irrigation applications under grapevine row (Kc,GR) could be a more realistic coefficient than Kc for producers and consultants to use in irrigation scheduling requirements. Irrigation frequency had a more significant impact on yield than canopy manipulation. Higher rainfall in 2013/14 increased vegetative growth and yield, with low frequency irrigations resulting in higher production water use efficiency compared to medium and high frequency irrigations. The incidence of grey rot was higher during the wetter season, with grapevines with sprawling canopies experiencing higher yield losses due to sun burn and less frequent irrigation. The highest incidences and yield loss to grey rot were found in grapevines left un-suckered and irrigated at ca. 30 PAW depletion, while irrigation at around 90 PAW depletion resulted in the absence of grey rot. Grapes were harvested near the target total soluble solids level of 24ºB, with severe water constraints enhancing berry maturation. Non-suckered VSP grapevines produced poorer quality at lower levels (30% and 60% depletion levels), with the highest overall wine quality obtained when irrigated at ca. 90% PAW depletion. Less frequent irrigations reduced summer canopy management requirements, but grapevines with more shoots required higher labour inputs at harvest. Pruning labour input requirements were affected by the number of shoots produced per grapevine and the mass per individual shoot. Sprawling canopy grapevines generally required lower labour costs, and pump costs were affected by the frequency of irrigation applications. During low to normal rainfall seasons, grapevines with sprawling canopies irrigated at ca. 60% PAW depletion produced the highest gross margins incomes, followed by box pruned grapevines irrigated at ca. 90% PAW depletion. In high summer rainfall seasons, box pruned grapevines and non-suckered VSP canopies had the highest gross margins. Grapevines with sprawling canopies, particularly those irrigated at ca. 60% PAW depletion, produced the best balance between yield and quality, ensuring the best gross margin incomes. The gross margin water use efficiency (WUEGM) increased with an increase in PAW depletion level irrigation, with box pruned grapevines consistently having the highest WUEGM. The study found that grapevines with sprawling canopies experienced lower diurnal and cumulative evaporation losses compared to VSP grapevines, regardless of PAW depletion levels. The higher mean leaf area per grapevine resulted in denser canopies, and treatments irrigated at approximately 30% PAW depletion were always within stage 1 of evaporation. Grapevines irrigated at around 60% PAW depletion occasionally went into stage 2, particularly in sprawling canopies. The water content of soil under grapevines irrigated at around 90% PAW depletion spent most of the season in stage 2. The vegetation coefficient (Kv) of sprawling canopies was lower than VSP grapevines, irrespective of PAW depletion. The VINET© model generally underestimated transpiration rates in wet soil regimes and overestimated them during dry soil regimes. Adjusting the model by addition of Kv and adapted transpiration water predictions can be done using two multilinear regressions after a few grapevine canopy measurements inputs have been considered.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Wingerdstokke wat teen lae plantbeskikbare water (PBW) ontrekkingspeile besproei is, het meer as dubbel die besproeiingsvolumes benodig in vergelyking met dié wat teen hoë ontrekkingspeile besproei is. Die verhoging in suikerakkumulasie van oophang lowers het gelei tot vroeër oesdatums, wat voor-oes besproeiingsvereistes verminder het. Verskillende lower manipulasies het nie die totale blaaroppervlakte (BA) per wingerd binne 'n besproeiingstrategie beïnvloed nie, maar het BA negatief beïnvloed waar minder water toegedien is. Ongesuierde wingerde het meer en geiler lootgroei geproduseer, terwyl ongesuierde vertikale loot-geposisioneerde (VLP) wingerde geneig was om laer lootmassas te produseer. Die BA- verspreiding verskaf 'n goeie aanduiding van loweroriëntasie, en nie-vernietigende metings van primêre- en sekondêre lote kan wintersnoei lootmassas voorspel. Dit sal wingerdboukundiges, produsente of besproeiingskonsultante in staat stel om die maksimum lootmassas te skat en die VINET© model te gebruik om wingerdwaterbehoeftes intyds regdeur die seisoen te voorspel, aangesien die LA met behulp van lootmassas geskat kan word. Wingerdstokke met oophang lowers het laer mid-dag blaarwater- (ΨL) en stamwaterpotensiale (ΨS) in vergelyking met dié met VLP lowers. Wingerde wat ernstige watertekorte ervaar het, het vinniger ryp geword as dié sonder of met medium watertekorte. Laefrekwensie besproeiing het watertekorte verhoog in vergelyking met hoëfrekwensie besproeiing. Dag- ΨL -siklusse het getoon dat wingerde met oophang lowers laer ΨL gehad het na 18:00 en dwarsdeur die nag, wat daarop dui dat hul watertekorte nie so vinnig soos VLP-wingerde kon herstel nie. Hoë besproeiingsfrekwensies het gelei tot hoër wingerdrye evapotranspirasie (ETGR) verliese, met verliese van oophang lowers, veral dié wat teen ca. 30% PBW onttrekking besproei was, wat hoër was in Januarie en Februarie as dié met VLP lowers. Seisoenale voloppervlak evapotranspirasie was meer sensitief vir besproeiingsfrekwensie as vir lower manipulasies. Wingerdstokke besproei teen ca. 30% PBW onttrekking het hoër gemiddelde voloppervlak gewas koëffisiënt (Kc) waardes in vergelyking met ander strategieë gehad, terwyl besproeiing ca. 90% PBW onttrekking die laagste gehad het. Die gemiddelde piek Kc is oor die algemeen in Februarie verkry vir wingerde wat teen lae frekwensies besproei is, terwyl die laagste Kc gedurende dieselfde tydperk gevind is vir lae frekwensie besproeiingstoedienings. Die fraksie grond wat deur drupbesproeiing benat word tydens besproeiingstoedienings onder wingerdrye (Kc,GR) kan 'n meer realistiese koëffisiënt as Kc wees vir produsente en konsultante om in besproeiingskeduleringsvereistes te gebruik. Besproeiingsfrekwensie het 'n meer beduidende impak op opbrengs gehad as lowermanipulasies. Hoër reënval in die 2013/14 seisoen het vegetatiewe groei en opbrengs verhoog, met lae frekwensie besproeiings wat gelei het tot hoër produksie waterverbruikeffektiwiteit in vergelyking met medium en hoë frekwensie besproeiings. Die voorkoms van vaalvrot was hoër gedurende die natter seisoen, met wingerde met oophang lowers wat hoër opbrengsverliese ervaar het as gevolg van sonbrand en minder gereelde besproeiing. Die hoogste voorkoms en produksie verlies aan vaalvrot is gevind in wingerde wat ongesuier gelaat was en teen ca. 30% PBW onttrekking besproei is, terwyl besproeiing teen ongeveer 90 PBW onttrekking gelei het tot die afwesigheid van vaalvrot. Druiwe is naby die teiken totale oplosbare vastestofvlak van 24ºB geoes, met erge waterbeperkings wat die rypwording van bessies verbeter het. Ongesuierde VLP-wingerde het swakker gehalte geproduseer teen laer vlakke (30% en 60% PBW onttrekking) besproei was, met die hoogste algehele wyngehalte wat verkry is wanneer besproei word teen ca. 90% PBW onttrekking. Minder gereelde besproeiings het lower bestuur vereistes verminder, maar wingerde met meer lote het hoër arbeidsinsette tydens oes vereis. Snoeiarbeid-insetvereistes is beïnvloed deur die aantal lote wat per wingerdstok geproduseer word en die massa per individuele loot. Oophang lower wingerde het oor die algemeen laer arbeidskoste vereis, en pompkoste is beïnvloed deur die frekwensie van besproeiingstoedienings. Gedurende lae tot normale reënvalseisoene het wingerde met oophang lowers wat teen ca. 60% PBW onttrekking besproei is, die hoogste bruto marge-inkomste opgelewer, gevolg deur meganies gesnoeide wingerde wat teen ca. 90% PBW onttrekking besproei was. In hoë somerreënvalseisoene het meganies gesnoeide wingerde en ongesuierde VLP lowers die hoogste bruto marges gehad. Wingerdstokke met oophang lowers, veral dié wat teen ca. 60% PBW onttrekking besproei was, het die beste balans tussen produksie en kwaliteit geproduseer, wat die beste bruto marge-inkomste verseker het. Die bruto marge watergebruikverbruikseffektiwiteit (WUEGM) het toegeneem met 'n toename in PBW onttrekking besproeiing, met meganies gesnoeide wingerde wat konstant die hoogste WUEGM gelewer het. Die studie het bevind dat wingerd met oophang lowers laer daaglikse en kumulatiewe verdampingsverliese ervaar het in vergelyking met VLP wingerd, ongeag van PBW onttrekking. Die hoër gemiddelde blaaroppervlakte per wingerdstok het digter blare tot gevolg gehad, en behandelings wat teen ongeveer 30% PBW onttrekking besproei was, was altyd binne fase 1 van verdamping. Wingerdstokke wat teen ongeveer 60% PBW besproei is, het soms in stadium 2 gegaan, veral die met oophang lowers. Besproeiing teen ca. 90% PBW onttrekking het die grootste deel van die seisoen in fase 2 van verdamping deurgebring. Die Vegetatiewe koëffisiënt (Kv) van oophang lowers was laer as VLP-wingerde, ongeag PBW onttrekking. Die VINET© model het oor die algemeen transpirasietempo's in nat grondregimes onderskat en dit tydens droë grondregimes oorskat. Die aanpassing van die model deur byvoeging van Kv en ‘n aangepaste transpirasie water voorspellings kan gedoen word deur twee multilineêre regressies te gebruik nadat 'n paar lowermeting insette in ag geneem word.af_ZA
dc.description.versionDoctorateen_ZA
dc.format.extentxxx, 223 pages : illustrations (some color), mapsen_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130228
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshGrapes -- Irrigation -- Managementen_ZA
dc.subject.lcshDeficit irrigationen_ZA
dc.subject.lcshGrapes -- Qualityen_ZA
dc.subject.lcshWine and wine making -- Environmental aspectsen_ZA
dc.subject.lcshPlant canopies -- Measurementen_ZA
dc.subject.lcshPlant canopies -- Effect of radiation onen_ZA
dc.subject.lcshPhotosynthesisen_ZA
dc.subject.lcshGrapes -- Water requirementsen_ZA
dc.subject.lcshWater efficiencyen_ZA
dc.subject.nameUCTDen_ZA
dc.titleDeficit irrigation and canopy management practices to improve water use efficiency and profitability of wine grapesen_ZA
dc.typeThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
lategan_deficit_2024.pdf
Size:
10.53 MB
Format:
Adobe Portable Document Format
Description:
Download
Collections
Doctoral Degrees (Soil Science)