A study of spatial and temporal natural intra-block variability of plant water status in a commercial vineyard
| dc.contributor.advisor | Poblete-Echeverria, Carlos | en_ZA |
| dc.contributor.advisor | Aleixandre-Tudo, Jose Luis | en_ZA |
| dc.contributor.author | Jasse, Aladino | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of Agrisciences. Dept. of Viticulture and Oenology. | en_ZA |
| dc.date.accessioned | 2021-03-08T08:30:18Z | |
| dc.date.accessioned | 2021-04-22T10:13:48Z | |
| dc.date.available | 2023-03-18T03:00:08Z | |
| dc.date.issued | 2021-03 | |
| dc.description | Thesis (MScAgric)--Stellenbosch University, 2021. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Water is one of the main elements responsible for plant growing and functioning. The most reliable method to measure the availability of water in plants is through the analysis of plant water status. Since plant water conditions have a significant role in grape and wine composition it is of utmost importance to control and manage the level of water deficit during the whole phenological cycle, more specifically during the ripening period. Plant water status variations during the ripening period have several consequences for the evolution of grape berry parameters and the biosynthesis of phenolic compounds in grape berries. In this period, water-stressed plants are prone to increase the concentration of certain parameters, such as sugar, and modify the biosynthesis of phenolic compounds. Plant water status is variable between plants within the vineyard block because several surrounding aspects influence the availability of water, and therefore, the absorption of water from the soil and the loss of water from the plant. Therefore, plant water status variability can be temporal according to the variability in the ripening period or spatial depending on plant conditions, soil characteristics and topography. Temporal and spatial variability can be monitored and evaluated by Precision Viticulture techniques. Precision Viticulture is an agricultural management approach that evaluates variability in vineyards with a focus on applying differentiated management practices to control intrinsic variability of vineyard blocks. The aim of this study was to evaluate natural temporal and spatial variability of plant water status during the growing season and to further investigate the effect that plant water status has on grape composition parameters (pH, TA, sugar) and wine phenolic compounds (Anthocyanins and Tannins). The existing literature concerning spatial variability of plant water status in vineyards was reviewed. Most studies in the field devote attention to the effect of Regulated Deficit Irrigation in the spatial variability of plant water status between plants. However, further work is needed to fully understand the implications of the natural spatial variability between plants in a vineyard block where also the surrounding characteristics (soil, diseases, microclimate) of each plant affect grape and wine composition. In Chapter 3, the natural spatial and temporal variability of plant water status in a commercial vineyard of cv. Cabernet Sauvignon was evaluated and mapped. Remote sensing measures of soil electrical conductivity, trunk circumference and satellite NDVI (Normalized Difference Vegetation Index) were used to select target vines in the block in addition to an unsupervised k- means function in order to create a grid of the spatial variability. Soil analysis and topography were also included in the analysis. As a result of the evaluation, 43 target plants were selected to be monitored from September to February. At the end of the season, three classes of plant water status were defined, and each target vine was assessed for yield, ripeness as well as standard juice parameters. Micro-vinification was done for each target vine and the concentration of anthocyanins and tannins was analysed. The results showed that the spatial and temporal variability of plant water status was evident along the season, affecting the grape parameters and wine concentration of phenolic compounds. An evident relationship between plant water status and soil texture and topography characteristics was noticed. Plants with a lower water status were located in steeper regions of the block with a higher water run-off and less water penetration in the soil. Compared with plants with a higher plant water status distributed in more flat regions of the block, plants with a low water status presented a significant increase in sugar content, anthocyanins and tannins and a strong decrease in yield. The findings of this thesis are a contribution to understand and quantify how spatial variability is naturally distributed and its effect on grape and wine parameters. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Water is een van die hoofelemente wat verantwoordelik is vir die groei en funksionering van plante. Die betroubaarste metode om die beskikbaarheid van water in plante te meet, is deur die ontleding van plantwaterstatus. Aangesien plantwatertoestande 'n belangrike rol speel in die samestelling van druiwe en wyn, is dit van uiterste belang om die vlak van waterspanning gedurende die hele fenologiese siklus te beheer en te bestuur, meer spesifiek gedurende die rypwordingsperiode. Plantwaterstatus variasies gedurende die rypwordingstydperk het verskeie gevolge vir die evolusie van druifkorrelparameters en vir die biosintese van fenoliese verbindings in wyn. In hierdie tydperk is plante wat onder spanning staan, geneig om die konsentrasie van sekere parameters, soos suiker, te verhoog en die biosintese van fenoliese verbindings te verander. Plantwaterstatus is wisselvallig tussen plante binne die wingerdblok, omdat verskeie omliggende aspekte die beskikbaarheid van water beïnvloed, en dus die assimilasie van water uit die grond en die verlies aan water van die plant. Daarom kan die verandering van plantwaterstatus tydelik wees volgens die wisselvalligheid in die rypwordingstydperk of ruimtelik, afhangende van planttoestande, grondkenmerke en topografie. Tydelike en ruimtelike variasie kan gemonitor en geëvalueer word deur Presisie-wingerdkunde tegnieke. Presisie wingerdkunde is 'n landboubestuursbenadering wat die wisselvalligheid in wingerdblokke evalueer met die fokus op die toepassing van gedifferensieerde bestuurspraktyke om die intrinsieke variasie van wingerdblokke te beheer. Die doel van hierdie studie was om die natuurlike tydelike en ruimtelike variasie van plantwaterstatus gedurende die groeiseisoen te evalueer en om die effek wat die status van plantwater op druifparameters (pH, TA, suiker) en wynfenoliese verbindings (Antosianiene en Tanniene) het, verder te ondersoek). Die bestaande literatuur oor ruimtelike veranderlikes van plantwaterstatus in wingerde is ondersoek. Die meeste studies in die veld bestee aandag aan die effek van gereguleerde tekortbesproeiing in die ruimtelike veranderlikheid van plantwaterstatus tussen plante. Verdere werk is egter nodig om die implikasies van die natuurlike ruimtelike variasie tussen plante in 'n wingerdblok ten volle te begryp, waar slegs die omliggende eienskappe (grond, siektes, mikroklimaat) van elke plant druif- en wynsamestelling beïnvloed. In hoofstuk 3 word die natuurlike ruimtelike en tydelike variasie van plantwaterstatus in 'n kommersiële wingerd van cv. Cabernet Sauvignon is geëvalueer en gekarteer. Afstandswaarnemingsmetings van elektriese geleidingsvermoë van die grond, stamomtrek en satelliet-NDVI (Normalised Difference Vegetation Index) is gebruik om teikenwingerde in die blok te kies, benewens 'n k-middelfunksie sonder toesig om 'n rooster van die ruimtelike veranderlikheid te skep. Grondontleding en topografie is ook by die ontleding ingesluit. As gevolg van die evaluering is 43 teikenplante gekies om van September tot Februarie gemonitor te word. Aan die einde van die seisoen is drie klasse plantwaterstremming gedefinieer en elke teikenrank beoordeel vir opbrengs, rypheid sowel as standaard sapparameters. Kleinskaal wynbereiding is vir elke teikenstok gedoen en die konsentrasie van antosianiene en tanniene is ontleed. Die resultate het getoon dat die ruimtelike en tydelike variasie van plantwaterstatus gedurende die seisoen duidelik was, en dat dit die veranderinge in die konsentrasie van fenoliese verbindings en druiwe-parameters beïnvloed het. Die wingerdstokke onder die gestresde klas het gepaard gegaan met veranderinge in grondtekstuur en topografie. Plante met n lae water status is gevind in styler areas van die blok wingerd met n hoe water afval en minder water penetrasie in die grond . As vergelyk word met plante met n hoe water status versprei in meer plat areas in blok kom dit voor dat plante met n lae water status n groter verhoging in suikerinhoud, anthocyanis en tanienne het en n sterk afname in volume vind plaas. Die bevindinge van hierdie proefskrif kan help om te verstaan en te kwantifiseer hoe ruimtelike variasie natuurlik versprei word en die effek daarvan op die druiwe- en wyngehalteparameters. | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.embargo.terms | 2023-03-08 | |
| dc.format.extent | 74 pages : illustrations (some color) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/110317 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject.lcsh | Grapes -- Breeding | en_ZA |
| dc.subject.lcsh | Grapes -- Composition | en_ZA |
| dc.subject.lcsh | Wine and wine making -- Chemistry | en_ZA |
| dc.subject.lcsh | Grapes -- Water requirements | en_ZA |
| dc.subject.lcsh | Plant water status -- Valuation | en_ZA |
| dc.subject.lcsh | Plants -- Effect of water levels on | en_ZA |
| dc.subject.lcsh | Phenols | en_ZA |
| dc.subject.lcsh | Intra-block variability -- Management | en_ZA |
| dc.subject.lcsh | Soil moisture -- Measurement | en_ZA |
| dc.subject.name | UCTD | en_ZA |
| dc.title | A study of spatial and temporal natural intra-block variability of plant water status in a commercial vineyard | en_ZA |
| dc.type | Thesis | en_ZA |