Paul Robert Petrie

South Australian Research and Development Corporation · Water Resources, Viticulture and Irrigated Crops

Associated with climate change, the frequency, duration, and intensity of heatwaves are increasing in most of the key wine regions worldwide. Depending on timing, intensity, and duration, heatwaves can impact grapevine yield and berry composition, with implications for wine quality. To overcome these negative effects, two types of mitigation practi...

Estimation of the plant available water capacity (PAWC) of soils at a regional scale helps in adopting better land use planning, developing suitable irrigation schedules for crops, and optimising the use of scarce water resources. In the current study, 72 soil profiles were sampled from the Barossa Region of South Australia to estimate pedo-transfe...

Background and Aims: Vineyard performance is impacted by water availability including the amount and seasonality of rainfall and evapotranspiration and irrigation volume. We benchmarked water-limited yield potential (Yw), calculated yield gaps as the difference between Yw and actual yield, and explored the underlying environmental and management ca...

Background and Aims: Vine phenology results from the interaction between the genotype, environment and management, with implications for fruit, and wine composition. The impact of weather, site and management practices, underlying elements of terroir, impacting the timing of key phenological stages were explored across the Barossa Zone (GI). Method...

The numerical model HYDRUS-UNSATCHEM was used to evaluate the impact of long-term (2018-2050) use of recycled water (RCW) for irrigation of the mixed pastures widely grown in Australia. The input parameters for soil hydraulic, soil solution and exchange data were determined from 14 representative soil profiles collected from the North Adelaide Plai...

Australia is exposed to a variety of climates due to its large size and meridional extent. The majority of Australia’s landscape lies in the southern subtropical region (15-20 degrees to 40 degrees south of the equator) except for parts of Northern Australia and Tasmania. The high degree of both seasonality and inter-annual variability arises due t...

Water availability for irrigation is a key management issue for Australian vineyards. Water scarcity is intensified due to climate variability and increased occurrence of droughts. Optimum irrigation application can help improve water use efficiency and regulate water stress to improve the sustainability of the production system. This study estimat...

Advancement of grapevine phenological stages due to climate change has been well documented. There is less information regarding which phenological intervals in the grapevine growth cycle are most affected by temperature and thus drive this advancement. This study focused on investigating the relationship between temperature and the phenological in...

Long-term use of recycled water (RW) for irrigation in arid and semiarid regions usually changes the soil solution composition and soil exchange characteristics, enhancing the risk for sa-linity and sodicity hazards in soils. This modelling study focuses on developing alternative management options that can reduce the potentially harmful impacts of...

Background and Aim Reduced rainfall during vine dormancy and supplementary irrigation during winter or at spring impact on vine growth partitioning. We assess the implications that induced changes on canopy growth due to soil moisture availability in spring have on fruit and wine composition. Methods and Results Irrigation strategies were assessed...

The variability of grapevine phenological stages under climate change have been studied in many winegrowing regions, with many reporting an advancement of the major phenological stages, particularly flowering, veraison and harvest. This study aimed to compare these regional patterns to integrate our understanding of grapevine responses. Average dai...

Background Stomata analysis using microscope imagery provides important insight into plant physiology, health and the surrounding environmental conditions. Plant scientists are now able to conduct automated high-throughput analysis of stomata in microscope data, however, existing detection methods are sensitive to the appearance of stomata in the t...

Background and Aims: Predicting the timing of critical grapevine phenological events such as harvest is still imprecise. The aims of this study were to better understand why grape maturity is advancing, and how different cultivars and regions are responding to the seasonal temperature conditions, to help better predict phenological timing and there...

Background and Aims Viticultural practices are needed to counteract widespread, deleterious effects of warming on fruit and wine attributes. Late pruning is an effective tool to delay fruit ripening and improve berry and wine attributes, but the interaction between late pruning and elevated ambient temperature on wine chemical and sensory propertie...

Digital image processing is commonly used in plant health and growth analysis, aiming to improve research efficiency and repeatability. One focus is analysing the morphology of stomata, with the aim to better understand the regulation of gas exchange, its link to photosynthesis and water use and how they are influenced by climatic conditions. Despi...

Powdery mildew (Erysiphe necator Schwein) is a major disease of grapevines. Extensive empirical information is available on the performance of fungicide programs, but little is known about the influence of cultivar, management system and especially the climate on grape growers’ fungicide use practices. Fungicide use records were analysed from a dat...

Changes to Australian regulations now allow the limited addition of water to high-sugar musts pre-fermentation. In light of these changes, this study explored how water addition affects Shiraz wine composition and sensory properties. Wines were made from grapes at ≈13.5, 14.5 and 15.5° Baume. Water was added to musts from the ripest fruit by direct...

Background and Aims Declining autumn and winter rainfall increasingly limits soil moisture availability at the onset of the growing season in southern Australia. We studied the consequences of reduced rainfall during dormancy on vine growth, and explored irrigation strategies to maintain yield following dry winters. Methods and Results The effect...

Background: Stomata analysis using microscope imagery provides important insight into plant physiology, health and the surrounding environmental conditions. Plant scientists are now able to conduct automated high-throughput analysis of stomata in microscope data, however, existing detection methods are sensitive to the appearance of stomata in the...

Background: Stomata analysis using microscope imagery provides important insight into plant physiology, health and the surrounding environmental conditions. Plant scientists are now able to conduct automated high-throughput analysis of stomata in microscope data, however, existing detection methods are sensitive to the appearance of stomata in the...

Background: Stomata analysis using microscope imagery provides important insight into plant physiology, health and the surrounding environmental conditions. Plant scientists are now able to conduct automated high-throughput analysis of stomata in microscope data, however, existing detection methods are sensitive to the appearance of stomata in the...

Altering the soil surface features can potentially regulate water and solute movement processes in the soils, and reduce the accumulation of salts in the plant root zone. In this study, HYDRUS-2D was used consecutively for three years (2011- 2014) to evaluate the potential impact of different rainfall redirection and water harvesting techniques suc...

Background and Aims Regulations in some wine‐producing countries allow water addition to grape must. The research presented compared the impact of water addition to must on wine phenolics and colour relative to that of wines at the same alcohol concentration, prepared from fruit harvested earlier. Methods and Results Shiraz grapes were harvested a...

The variably-saturated flow and multi-component transport module UNSATCHEM of HYDRUS-1D was used to evaluate the impact of the long-term (2018-2050) application of recycled water (RCW) for irrigating perennial horticulture (almonds, pistachios), viticulture (grapevines), annual horticulture (carrot, onion, and potato), and pasture crops in represen...

Background and Aims: Understanding the dynamics of the components of evapotranspiration and irrigation requirements in response to climate variation and change is essential to sustainably managing vineyards. Methods and Results: The FAO-56 dual crop coefficient was used to evaluate wine grape evapotranspiration (ETC_adj), seasonal transpiration (T...

As grapegrowers move to adapt to climate change, they need more detailed information on what cultivars to plant and where to plant them. The aims of this study were to understand how different cultivars in different regions are responding to changes in climate, in order to inform future cultivar selections. Trends in the day of year maturity (DOYM)...

Stem water potential Smartphone application Smartphones have several advantages over specialist monitoring systems including ubiquity, price, and ease of implementing updates. Thermal imaging can be used to assess plant water status and allow more informed irrigation decisions; unfortunately, this technique has not been widely adopted due to the hi...

Imaging beyond RGB bands has the ability to provide solutions for non-destructive detection of objects or scene properties. Methods often used in research include hyperspectral cameras and spectrometers; the former is expensive and the latter can only provide point measurements. Multispectral imaging can provide low-cost solutions in instances wher...

Background and Aims Rapid and non‐destructive techniques for measuring grape composition have the potential to improve harvest decisions and to allow the batching of fruit into parcels of similar composition to improve processing efficiency. If such techniques are to be based on the non‐destructive assessment of visible berries, then relationships...

Recent warming has shortened and compressed vintages and has altered enologically relevant berry traits. Late pruning can decompress harvest and preserve fruit quality. Here, we were interested in exploring the interactive effects of late pruning and heating on Shiraz development and composition. We established a factorial experiment that combined...

Automated flower counting systems have recently been developed to process images of grapevine inflorescences, which assist in the critical tasks of determining potential yields early in the season and measurement of fruit-set ratios without arduous manual counting. In this paper, we introduce a robust flower estimation system comprised of an improv...

Smartphones have several advantages over specialist systems for extending crop monitoring technology to small to medium scale horticultural operators, including ubiquity, price, user familiarity and the ease of implementing updates. They also contain sufficient computing power that analysis and support software can be contained within the phone. Th...

Aim: To evaluate the effect of elevated temperature on the yield of Shiraz vines in the Barossa Valley of Australia. Methods and results: We compiled and analysed 37 pair-wise yield comparisons between heated and control vines spaning seven consecutive vintages from 2009-10. Heating with open-top chambers increased daily average temperature by appr...

Background and Aims Warming has two major effects on the wine industry: compressing harvest duration, thus stressing the current capacity of wineries to process more fruit in a shorter time, and compromising fruit composition and wine style. Late pruning can effectively delay vine development and contribute to decompressing harvest, but its impact...

Background Stomatal behavior in grapevines has been identified as a good indicator of the water stress level and overall health of the plant. Microscope images are often used to analyze stomatal behavior in plants. However, most of the current approaches involve manual measurement of stomatal features. The main aim of this research is to develop a...

The shift in phenological development is the most conspicuous biological effect of climate change in vineyards worldwide. Associated with the advancement in maturity there has been a compression of the harvest period that places significant pressure on vineyard and winery infrastructure. Our aims were to test the feasibility of using delayed prunin...

Global warming is shifting vine phenology, compressing harvests and altering the balance of fruit traits relevant to wine. Our aim was to test late pruning as a tool to delay maturity and to assess carry-over effects from repeated late pruning on phenology, yield components, dynamics of leaf area and berry traits of Shiraz grown in the Barossa Vall...

Accurate estimation of evapotranspiration (ET) and its partitioning into transpiration and evaporation is fundamental for improving water management practices in water-limited environments and under deficit irrigation conditions. This investigation was conducted to estimate the water balance and ET components of subsurface drip (SDI) irrigated Char...

The impact of high temperature on grapevine function is predicted to be a serious problem in our warming climate. We studied the impact of shading on some aspects of vine physiology, berry cell death and other components of berry development and on the resultant wines in order to understand grapevine physiology and the ripening process in shaded co...

A fast image processing method is proposed for detecting stomata and measuring stomatal aperture size in individual images. The accuracy of aperture measurements is 97\%. A prototype mobile application is developed to assist field measurements.

Climate change is expected to have a significant impact on the wine industry, and as an industry, it is critical that practices are evaluated to ensure opportunities to mitigate greenhouse gas (GHG) emissions are identified. Data from Australian vineyards were examined and compared with international data to identify the sources of GHG emissions in...

Petioles, rachis, and leaves are all matter other than grape (MOG), and although originating from vines, they potentially contaminate primary fermentations of red grape must. Fruit contaminated with high levels of MOG may be downgraded or rejected at the winery; however, management practices such as hand harvesting or fruit sorting may reduce MOG....

Background and AimsInteractions are the main causes of complexity in field experiments; however, no studies have combined water and temperature regimes in field-growing vines. Here we assessed grape and wine attributes from a field trial where these factors were directly manipulated.Methods and ResultsThe experiment consisted of Shiraz vines grown...

Poor water quality and lack of rainfall can lead to higher salt loads in vineyard soil and the production of wine with sodium chloride (NaCl) concentrations that may affect wine quality or exceed regulatory limits. Here, study 1 aimed to determine NaCl sensory thresholds in grape juice and wine so that better harvest and processing decisions could...

Background and AimsThe effects of vineyard temperature on wine attributes are largely inferred from indirect comparisons between thermally contrasting regions and vintages. Here, we directly assessed wine attributes in trials where manipulation of temperature in the field minimised confounded effects typical of indirect comparisons. Methods and Res...

Background and Aim: To predict harvest time for logistic applications in vineyards and wineries, measurements of total soluble solids (TSS) are typically combined with projections assuming TSS increases at 1°Bé/week. Here, three questions were asked: (i) what is the magnitude and direction of the bias in estimates of ripening assuming 1°Bé/week acr...

Background and Aim: To predict the trajectory of sugar accumulation in berries for planning of harvest and post-harvest operations, we derived a simple model that is consistent with the known biological and viticultural drivers of berry ripening and requires inputs that are readily available to industry. Methods and Results: We used data from three...

Background and Aim: Early maturity of grape crops associated with recent warming is well documented but poorly understood. Here, we ask the question: is early maturity associated with early onset of ripening or with increased rate of sugar accumulation? Methods and Results: We used records of grape juice total soluble solids (TSS) for Chardonnay, S...

Background and Aims: Bunch number per node or shoot varies significantly between seasons and is a major cause of yield variation. Varying total node numbers by pruning is the least expensive way to regulate yield. However, there is little information available on how varying bearer length (and thus node number) in a machine-pruned canopy alters yie...

A portable, open gas exchange system was developed that enabled the simultaneous measurement of net carbon dioxide exchange (NCE) and transpiration of eight mature Sauvignon blanc grapevines in the field. On clear and cloudy days NCE and transpiration were closely related to the modeled interception of photosynthetically active radiation (PAR). On...

This paper focuses on the interaction between genotype and environment, a critical aspect of plant breeding, from a physiological perspective. We present a theoretical framework largely based on Bradshaw's principles of phenotypic plasticity (Adv. Gen. 13: 115) updated to account for recent developments in physiology and genetics. Against this fram...

The impact of mechanical thinning using a machine harvester on yield components and fruit composition of Tempranillo and Grenache (Vitis vinifera L.) vines was investigated. Experiments were conducted in two Spanish vineyards, both trained to a vertical shoot-positioned canopy over two consecutive seasons. The height of the harvester and the positi...

Background and Aims: The understanding of the links between weather and wine quality is fragmented and often qualitative. This study quantified and integrated key weather variables during ripening, and their influence in red wine quality in the Hunter Valley, Margaret River, Coonawarra and Barossa Valley. Methods and Results: Long-term records of p...

Plastic mini-chambers were used as tiny ‘glass houses’ to increase bud temperature in the vineyard. Open containers, with holes cut in them for ventilation, were used as controls, and inflorescences produced in those chambers were compared with inflorescences from modified chambers where either shade cloth or reflective foil were used to alter inte...

Background and Aims:  Recent warming has accelerated phenological development of many crops. We quantified the rate of change in date of designated maturity (21.8°Brix), date of harvest, and sugar concentration of berries at harvest in Chardonnay, Cabernet Sauvignon and Shiraz between 1993 and 2006.Methods and Results:  Data from 18 Australian regi...

Treatments varying source:sink ratio (leaf number per vine in relation to crop load) on container-grown Pinot Noir grapevines produced differences in vine growth and dry matter accumulation and partitioning. Vines with (+) and those without (-) fruit were subject to a range of leaf removal treatments. All treatments retained leaves at nodes 1–4 fro...

This paper quantifies time-trends of vintage scores and their variability in 24 wine regions of Australia. Our working hypotheses are that, owing to improved crop husbandry and winemaking techniques, (1) vintage scores had increased with time, and (2) variability in vintage scores had decreased with time, whereas (3) interactions between improved t...

Crop thinning subsequent to fruit set can help regulate yield and improve fruit composition at harvest. Accordingly, an experiment was established in two vineyards (Site 1 Riverland District of South Australia; Site 2 Sunraysia District of Victoria) to investigate effects of crop removal after fruit set (when berries were pea size) using a machine...

Given their perennial nature, grapevines can respond to deficit irrigation during both the current season as well as during the following season, even though full irrigation may have been restored during that second season. To define the cropping responses involved, three post-veraison irrigation treatments were imposed on spur, mechanically and mi...

Seyval blanc' (Vitis vinifera L.) is an important French-American hybrid white wine cultivar grown in the Great Lakes region because of its disease and phylloxera resistance and cold hardiness. It does, however, have some limitations. It forms large, compact clusters susceptible to Botrytis bunch rot under Michigan's cool, wet climate and post-rain...

Canopy topping and leaf removal are management practices commonly used in New Zealand vineyards to increase light and pesticide penetration to the fruit zone, thus, reducing disease incidence. Previous research has suggested that an increase in photosynthesis occurs when leaves are removed, and this may compensate for the reduced leaf area. However...

The objective of the project described in this thesis was to assess the influences on grapevine growth, fruit yield and quality of management practices, including training system (Vertical Shoot Positioning (VSP) versus Scott-Henry (S-H)), leaf removal and fruit removal. This was achieved using a whole-vine gas exchange system that was developed to...

Fruit development from pea size to maturity was investigated in grape berries on fruit-bearing cuttings subjected to a range of leaf removal treatments. Pot-grown vines were trained as a single shoot, with four basal leaves retained. From this point four treatments were applied: 100% leaves retained (control); 66% leaves retained; 33% leaves retain...

Treatments varying the leaf area (source) to crop load (sink) balance of pot-grown Pinot noir vines caused differences in the photosynthesis (Pn) rates of the fourth leaf, 48 h after they were applied, Stomatal conductance was only affected by leaf removal, not by the presence or absence of crop. The vines with and without crop were subject to a ra...