Influence of leaf ageing, leaf area and crop load on photosynthesis, stomatal conductance and senescence of grapevine (Vitis vinifera L. cv. Pinot noir) leaves

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 range of leaf removal treatments. All treatments retained leaves at nodes 1-4 from the shoot base and then had 100%(control), 66 %, 33 %, or 0 % leaves retained from node 5 to the apex of the shoot. Leaf removal elevated the Pn rate of the fourth leaf, but there was no difference in Pn rate between vines with or without crop pre-veraison. From veraison on the photosynthetic rate of vines with crop and 100 % leaves retained increased. Similar, high Pn rate was also observed for vines without crop and 0 % leaves retained. The lower Pn rate of vines with crop pre-veraison suggests that there is potential to increase vine productivity in this period. The Pn rate of vines without crop, 100 % and 66 % leaves retained declined from 15 d after treatment. Average Pn of all treatments over the 4 measurements prior to harvest was positively correlated with the vine leaf area (source) to total vine dry weight (sink) ratio. Leaves of vines with a high source:sink ratio (without crop, 100, 66 or 33%leaves retained) senesced i.e. decreased in chlorophyll content more rapidly than leaves of the low source to sink ratio treatments. Results indicate that the decline in grapevine leaf Pn, previously associated with advanced leaf age is actually caused by a progressive increase in leaf area to fruit weight (source:sink) ratio, as leaves emerge on the developing vine

Reduced grapevine canopy size post-flowering via mechanical trimming alters ripening and yield of 'Pinot noir'

The degree and time of canopy trimming can alter phenology, rates of increase or decrease in berry components during grape ripening, and may influence yield and its components. The objective of this study was to investigate the extent to which reducing canopy size, by mechanical trimming post-flowering, changed Vitis vinifera L. 'Pinot noir' fruit yield and composition. Vines were mechanically trimmed to three different canopy heights at fruitset: 1000 mm (100 % canopy height), 600 mm (60 % canopy height relative to the control treatment) and 300 mm (30 % canopy height relative to the control treatment). Total soluble solids concentration and content, titratable acidity, pH and fresh berry mass were measured throughout ripening, and yield and leaf area were measured at harvest.Reduced canopy size via trimming to 30 and 60 % of the control treatment height slowed total soluble solids accumulation and in some cases increased titratable acidity and increased pH. The total soluble solids-titratable acidity ratio was therefore reduced throughout ripening by these trimming treatments relative to the full canopy height. Trimming to reduce canopy size had two effects on the source-sink ratio; it reduced the source (canopy) but increased fruit yield, an important sink. Therefore, the time of trimming is an important management consideration because it can delay and slow ripening due to reduced source leaves but could potentially accentuate the delay via increasing yield (sink). This technique may represent a way to offset the acceleration of phenology and grape ripening that has been observed to occur as a result of warmer seasons

Developing perennial fruit crop models in APSIM Next Generation using grapevine as an example

A new model for grapevines (Vitis vinifera) is the first perennial fruit crop model using the Agricultural Production System sIMulator (APSIM) Next Generation framework. Modules for phenology, light interception, carbohydrate allocation, yield formation and berry composition were adapted or added into APSIM Next Generation to represent the nature of fruit-bearing vines. The simulated grapevine phenological cycle starts with the dormancy phase triggered by a critical photoperiod in autumn, and then goes through the subsequent phenophases sequentially and finally returns to dormancy for a new cycle. The canopy microclimate module within APSIM Next Generation was extended to allow for row crop light interception. The carbohydrate arbitrator was enhanced to consider both sink strength and sink priority to reflect carbohydrate reserve as a concurrent competing sink. Weather conditions and source-sink ratio at critical developmental stages were used to determine potential grapevine yield components, e.g. bunch number, berry number and berry fresh weight. The model was calibrated and tested extensively using four detailed data sets. The model captured the variations in the timing of measured budburst, flowering and véraison over 15 seasons across New Zealand for five different varieties. The calculated seasonal dynamics of light interception by the row and alley were consistent with field observations. The model also reproduced the dynamics of dry matter and carbohydrate reserve of different organs, and the wide variation in yield components caused by seasonal weather conditions and pruning regimes. The modelling framework developed in this work can also be used for other perennial fruit crops

Potential of a multiparametric optical sensor for determining in situ the maturity components of red and white vitis vinifera wine grapes

A non-destructive fluorescence-based technique for evaluating Vitis vinifera L. grape maturity using a portable sensor (Multiplex ®) is presented. It provides indices of anthocyanins and chlorophyll in Cabernet Sauvignon, Merlot and Sangiovese red grapes and of flavonols and chlorophyll in Vermentino white grapes. The good exponential relationship between the anthocyanin index and the actual anthocyanin content determined by wet chemistry was used to estimate grape anthocyanins from in field sensor data during ripening. Marked differences were found in the kinetics and the amount of anthocyanins between cultivars and between seasons. A sensor-driven mapping of the anthocyanin content in the grapes, expressed as g/kg fresh weight, was performed on a 7-ha vineyard planted with Sangiovese. In the Vermentino, the flavonol index was favorably correlated to the actual content of berry skin flavonols determined by means of HPLC analysis of skin extracts. It was used to make a non-destructive estimate of the evolution in the flavonol concentration in grape berry samplings. The chlorophyll index was inversely correlated in linear manner to the total soluble solids (°Brix): it could, therefore, be used as a new index of technological maturity. The fluorescence sensor (Multiplex) possesses a high potential for representing an important innovative tool for controlling grape maturity in precision viticulture

The effect of pre-budbreak cane girdling on the physical and phenological development of the inner and outer arm in Vitis vinifera L. 'Sauvignon blanc' inflorescence structures

The development of inflorescence primordia (IP) into floral bearing structures is influenced by many environmental and genetic factors. We hypothesise that carbohydrate (CHO) availability at budbreak (BB) has a strong influence on IP development, especially during the initial stages of shoot growth when pre-formed IP emerge from dormant buds and may be dependent on reserve CHOs for further branching and development. Carbohydrate availability to developing grapevine buds (Vitis vinifera L. 'Sauvignon blanc') was manipulated by girdling canes two weeks before BB. Dates of flowering, flower number, berry number and grape berry soluble solids (SS) were measured for the inner and outer arm bunch components of basal and apical bunches separately. Restricting pre-BB CHOs resulted in the abortion of some pre-formed inflorescences and reduced branching of the inflorescences that did develop. In general, berry SS were greatest for the basal inner arm, followed by those of the apical bunch inner arm, then those of the basal bunch outer arm, then lastly by those of the apical bunch outer arm. However, this was influenced by the relative berry numbers between the inner and outer arm. Bunches with more similar berry numbers on the inner and outer arms had more synchronous flowering and uniform SS, where the differences in SS were largely a reflection of the timing of flowering of the various inflorescence components and may be an important source of variation in SS within a vine at harvest

Influence of cane diameter on gross profit

Mark Eltom, from New Zealand’s Lincoln University, Department of Wine, Food & Molecular Biosciences; together with Chris S. Winefield, and Mike C.T. Trought have been studying how cane diameter and structure influence the gross return to growers. This report is based on their paper “Effects of shoot girdling and/or periodic leaf removal on inflorescence primordia initiation and development in Vitis vinifera L. cv. Sauvignon Blanc”, portions of which have previously been published in the Australian Journal of Grape and Wine Research and Practical Winery & Vineyard

Grapevine phenology of the Marlborough region, New Zealand

High resolution temporal and spatial temperature mapping together with phenology models are being used to predict the time and duration of key phenological events of Sauvignon blanc grapevines. The objectives of the research are to: 1) develop models to enable industry to anticipate the consequences of climate variation for phenology within the Marlborough region, and 2) to enable growers to consistently produce fruit of optimum composition for the Marlborough wine style. By combining field measurements of grapevine response, automatic weather station data, improved phenological models, and advanced high-resolution weather prediction models, web-based tools are being developed to help wine-makers adapt to changing conditions so that they can continue to produce high quality wine

Application of high-resolution climate measurement and modelling to the adaptation of New Zealand vineyard regions to climate variability

Initial results are presented of research into the relationship between climate variability and viticulture in New Zealand vineyards. Atmospheric modelling and analytical tools are being developed to improve adaptation of viticultural practices and grape varieties to current and future climate. The research involves application of advanced local and regional scale weather and climate models, and their integration with grapevine phenological and crop models. The key aims are to improve adaptation of grape varieties to fine scale spatial variations of climate, and reduce the impact of climate variation and risk factors such as frost, cool spells and high temperatures. Improved optimization of wine-grape production through better knowledge of climate at high resolution within vineyard regions will contribute to the future sustainability of high quality wine production. An enhanced network of automatic weather stations (AWS) has been installed in New Zealand’s premier vineyard region (Marlborough) and the Weather Research and Forecasting (WRF) model has been set up to run twice daily at 1 km resolution through the growing season. Model performance has been assessed using AWS data and the model output is being used to derive high-resolution maps and graphs of bioclimatic indices for the vineyard region. Initial assessment of model performance suggested that WRF had a cold bias, but this was found to be due to errors in the default surface characteristics. Spatial patterns of predicted air temperature and bioclimatic indices appear to accurately represent the significant spatial variability caused by the complex terrain of the Marlborough region. An automated web page is being developed to provide wine-producers with daily up-dates of observed and modelled information for the vineyard region. Latest results of this research will be provided along with a review of the 2013-14 growing season, using data from both the climate station network and WRF model output

Analysis of viticulture region climate structure and suitability in New Zealand

Aims: This research analyzes four climate indices derived from gridded, interpolated data to assess New Zealand’s climate structure and variation among wine regions. Methods and results: High resolution gridded data based on 1971-2000 climate normals was used to characterize climate indices depicting viticultural suitability in a geographic information system. The statistical properties of each index were assessed over 21 New Zealand viticulture regions. The results show predominately cool to moderately warm climate suitability in New Zealand, comparable to many European and United States regions. While many viticulture regions have one primary class of suitability, variability of climate within regions can be significant, with some regions containing two to four climate classes, making them suitable for a greater range of cultivars. Conclusion: While the indices depict broad patterns expected over New Zealand, both within and between region variations can be substantial among the indices. However, two indices, Growing Season Average Temperature (GST) and Growing Degree-Days (GDD), are functionally identical, but GST is easier to calculate and overcomes many methodological issues in GDD. Significance and impact of the study: This research provides the basis for evaluating general suitability for viticulture in New Zealand, assists comparisons between viticulture regions in New Zealand and worldwide, and offers growers measures of assessing appropriate cultivars and sites