Management zones delineation using fuzzy clustering techniques in grapevines

Precision viticulture aims at managing vineyards at a sub-field scale according to the real needs of each part of the field. The current study focused on delineating management zones using fuzzy clustering techniques and developing a simplified approach for the comparison of zone maps. The study was carried out in a 1.0 ha commercial vineyard in Central Greece during 2009 and 2010. Variation of soil properties across the field was initially measured by means of electrical conductivity, soil depth and topography. To estimate grapevine canopy properties, NDVI was measured at different stages during the vine growth cycle. Yield and grape composition (must sugar content and total acidity) mapping was carried out at harvest. Soil properties, yield and grape composition parameters showed high spatial variability. All measured data were transformed on a 48-cell grid (10 × 20 m) and maps of two management zones were produced using the MZA software. Pixel-by-pixel comparison between maps of electrical conductivity, elevation, slope, soil depth and NDVI with yield and grape composition maps, set as reference parameters, allowed for the calculation of the degree of agreement, i.e. the percentage of pixels belonging to the same zone. The degree of agreement was used to select the best-suited parameters for final management zones delineation. For the year 2009 soil depth, early and mid season NDVI were used for yield-based management zones while for quality-based management zones ECa, early and mid season NDVI were utilized. For the year 2010 ECa, elevation and NDVI acquired during flowering and veraison were used for the delineation of yield-based management zones while for quality-based management zones ECa and NDVI acquired during flowering and harvest were utilized. Results presented here could be the basis for simple management zone delineation and subsequent improved vineyard management.     

Vineyard zone delineation by cluster classification based on annual grape and vine characteristics

This study describes a method for vineyard zone delineation based on spatial interpolation of data on annual monitoring of grape and vine growth from 2007 to 2012 for four commercial vines (Cabernet Sauvignon, Mencía, Merlot and Tempranillo) located in the Bierzo Denomination of Origen (NW Spain). A sampled grid of 20 × 29 m (14 vines/ha) was defined for each vineyard and data were collected for ten soil, six grape composition, three grape production and five vine vigour variables. Continuous maps of each variable were created by spatial interpolation from the sampled points. Several zone delineations were obtained by clustering—using the iterative self-organizing data analysis (ISODATA) algorithm—according to different combinations of the studied variables. The resulting zone delineations were analysed (ANOVA) in order to determine whether the variables in the two cluster classifications for two or three zones were statistically different from each other. The selected delineation was the cluster that included total soluble solids, titratable acidity, total phenolic content, pH, mean cluster weight and length of the internode in two zones. The results point to the feasibility of this approach to vineyard zone delineation. Further research is necessary to confirm the effectiveness of this approach for other locations and evaluate the usefulness of introducing new grape and vine variables.     

Are precision agriculture tools and methods relevant at the whole-vineyard scale?

Precision viticulture (PV) has been mainly applied at the field level, for which the ability of high resolution data to match within-field variability has been already shown. However, the interest of PV for grape growers would be greater if its principles could also apply at a larger scale, as most growers still focus their management on a multi-field scale, not considering each field as an isolated unit. The aim of this study was to analyse whether it is possible and relevant to use PV tools to define meaningful management zones at the whole-vineyard scale. The study was carried out on a 90-ha vineyard made of 27 contiguous fields. The spatial variability of vine vigour, estimated with the Normalized Difference Vegetation Index (NDVI), was analysed at within-field and whole-vineyard scales. The spatial variability of the vigour was significant and spatially organized whatever the considered scale. Besides, vineyard spatial variability was characterised using information on environmental factors (soil apparent conductivity and elevation) and vine response (yield, vigour and grape composition). At both scales, NDVI and measured environmental factors were used to establish a three-level classification, whose agronomic significance was tested comparing the vine response observed for each class. The analysis of high resolution information allowed the definition of classes with agronomic and oenological implications, although there was not a straightforward correspondence between the classes defined and quality. Analysing the variability at the whole-vineyard scale highlighted a trend of spatial variation associated to elevation that was hardly visible at the within-field level.     

Integration of optical and analogue sensors for monitoring canopy health and vigour in precision viticulture

Remote-Sensing (RS) is the most widely used technique for crop monitoring in precision viticulture systems. This paper considers the possibility of substituting RS information obtained by various proximal sensing technologies employed directly in vineyards in order to enable a simultaneous evaluation of canopy health and vigour status. To this aim, a mobile lab has been developed. It consists of (a) two GreenSeeker RT100 sensors, a commercial optical device calculating NDVI, and Red/NIR indices in real time; (b) three pairs of ultrasonic sensors to estimate canopy thickness; and (c) a DGPS receiver to geo-reference data collected while travelling in a vineyard. During the 2007–2008 campaign, tests were carried out in a commercial vineyard in order to evaluate the monitoring system performance regarding disease appearance, diffusion, and vegetative development variations due to the normal growing process of vines. Surveys with the mobile lab were conducted in two groups of rows, treated and untreated with agrochemicals, and compared to manual morphological and physiological observations that characterised the phytosanitary status of the canopy. Measurement repeatability was verified; both NDVI values and ultrasonic data showed high repeatability (with r = 0.88 and r = 0.85, respectively). Optical data were processed in order to obtain NDVI maps, which clearly showed differences in canopy vigour evolution in the two examined groups, with low vegetative vigour in areas infected by Plasmopara viticola, as confirmed by manual assessment. Maps of the percentage infection index (I%I) were produced according to pathological manual survey results. The comparison between I%I and NDVI maps qualitatively confirmed the real vine phytosanitary status. Ultrasonically measured canopy thickness (UCT) was calculated and compared to manually measured canopy thickness (MCT) (r = 0.78). UCT and NDVI values were compared in order to identify areas affected by disease among zones presenting critical vegetation conditions.     

Assessment of the spatial variability of anthocyanins in grapes using a fluorescence sensor: relationships with vine vigour and yield

The use of new, rapid and non-invasive sensors in the field allows the collection of many observations which are necessary to assess the spatial variability of berry composition. The aim of this work was to study the spatial variability in anthocyanin content in grapes and to quantify its relationship with the vigour and yield in a commercial vineyard. The study was conducted in a Tempranillo (Vitis vinifera L.) vineyard (Navarra, Spain). A new, hand-held, non-destructive fluorescence-based proximal sensor was used for monitoring the anthocyanin content in grapes at veraison and harvest. Yield, vine vigour, spectral (normalized difference vegetation index and plant cell density) and chlorophyll (SPAD and simple chlorophyll fluorescence ratio) parameters were measured. Yield variability within the vineyard was the largest of all the parameters. Fluorescence-based anthocyanin indices were less variable at harvest than at veraison. The vigour parameters (main shoot length, total shoot length and shoot pruning weight) were positively correlated to yield; the chlorophyll and the spectral indices were negatively correlated with berry anthocyanin production. The correlations between vigour, yield and anthocyanin content in grapes varied substantially in time and space across the vineyard.     

Crop height variability detection in a single field by multi-temporal terrestrial laser scanning

Information on crop height, crop growth and biomass distribution is important for crop management and environmental modelling. For the determination of these parameters, terrestrial laser scanning in combination with real-time kinematic GPS (RTK–GPS) measurements was conducted in a multi-temporal approach in two consecutive years within a single field. Therefore, a time-of-flight laser scanner was mounted on a tripod. For georeferencing of the point clouds, all eight to nine positions of the laser scanner and several reflective targets were measured by RTK–GPS. The surveys were carried out three to four times during the growing periods of 2008 (sugar-beet) and 2009 (mainly winter barley). Crop surface models were established for every survey date with a horizontal resolution of 1 m, which can be used to derive maps of plant height and plant growth. The detected crop heights were consistent with observations from panoramic images and manual measurements (R² = 0.53, RMSE = 0.1 m). Topographic and soil parameters were used for statistical analysis of the detected variability of crop height and significant correlations were found. Regression analysis (R² < 0.31) emphasized the uncertainty of basic relations between the selected parameters and crop height variability within one field. Likewise, these patterns compared with the normalized difference vegetation index (NDVI) derived from satellite imagery show only minor significant correlations (r < 0.44).     

The potential of high spatial resolution information to define within-vineyard zones related to vine water status

The goal of this study was to test the usefulness of high-spatial resolution information provided by airborne imagery and soil electrical properties to define plant water restriction zones within-vineyards. The main contribution of this is to propose a study on a large area representing the regions’ vineyard diversity (different age, different varieties and different soils) located in southern France (Languedoc-Roussillon region, France). Nine non-irrigated plots were selected for this work in 2006 and 2007. In each plot, different zones were defined using the high-spatial resolution (1 m²) information provided by airborne imagery (Normalised Difference Vegetation Index, NDVI). Within each zone, measurements were conducted to assess: (i) vine water status (Pre-dawn Leaf Water Potential, PLWP), (ii) vine vegetative expression (vine trunk circumference and canopy area), (iii) soil electrical resistivity and, (iv) harvest quantity and quality. Large differences were observed for vegetative expression, yield and plant water status between the individual NDVI-defined zones. Significant differences were also observed for soil resistivity and vine trunk circumference, suggesting the temporal stability of the zoning and its relevance to defining vine water status zones. The NDVI zoning could not be related to the observed differences in quality, thus showing the limitations in using this approach to assess grape quality under non-irrigated conditions. The paper concludes with the approach that is currently being considered: using NDVI zones (corresponding to plant water restriction zones) in association with soil electrical resistivity and plant water status measurements to provide an assessment of the spatial variability of grape production at harvest.     

Enhancing the value of field experimentation through whole-of-block designs

Precision agriculture (PA) offers opportunities for the development of new approaches to on-farm experimentation to assist farmers with site-specific management decisions. Traditional agricultural experiments are usually implemented in fields with the least possible soil heterogeneity under the assumption that responses to inputs and inherent variation of the soil are additive components of yield variation. However, because the soil in typical fields is not homogeneous, PA has much to offer. Farmers faced with variable conditions need to optimize their management to the variation over space and time on their farm, a problem that is not solved by conventional approaches to experimentation. New designs for on-farm experiments were developed in the 1990s for cereal production in which the whole field was used for the experiment rather than small plots. We explore the extension of this type of experiment to a vineyard in the Clare Valley of South Australia aiming to evaluate options to increase grape yield and vine vigour. Manually sampled indices of vine performance measured on georeferenced ‘target’ grapevines were analysed geostatistically. The major advantage of such an approach is that the spatial variation in response to experimental treatments can be examined. Linear models of coregionalization, pseudo cross-variograms and standardized ordinary cokriging are used to map treatment responses over the experimental area and also the differences between them. The results indicate that both treatment responses and the significance of differences between them are spatially variable. Thus, we conclude that whole-of-block on-farm trials are useful in vineyards.     

山地土壤养分及其对酿酒葡萄生长发育的影响

对陕西省耀县山地不同海拔高度三个酿酒葡萄园0￣60cm土层土壤的养分及葡萄生长发育进行了研究。结果表明:各葡萄园土壤pH均在8.0左右,属石灰性土壤;土壤有机质和N、P、K等大量元素含量偏低,各种微量元素除了有效B含量很低以外,其它元素含量均丰富。植株生长量以海拔最低的葡萄园大于其它两地。果实糖酸比随海拔升高而降低,总酚和单宁含量以海拔居中处的最高。     

低效葡萄园改造更新技术

分析了低效葡萄园的特点及形成原因,提出可采取增株加行、压蔓更新、架式改造、树形改造、嫁接改良新品种等措施来进行低效葡萄园的改造更新。     

葡萄枝条栽培白玉菇的营养成分研究

以传统栽培料(杂木屑)栽培的白玉菇为对照,比较用“户太8号”和“红地球”葡萄冬季修剪枝条为主料栽培的白玉菇,依据相关国家标准对3种白玉菇样品的营养成分进行测定与评价。结果表明,用2种葡萄枝条栽培出的白玉菇品质在多方面均几无降低,且在多方面优于传统栽培料栽培出的白玉菇。     

Setting the optimal length to be scanned in rows of vines by using mobile terrestrial laser scanners

Mapping the leaf area index (LAI) by using mobile terrestrial laser scanners (MTLS) is of significance for viticulture. LAI is related to plant vigour and foliar development being an important parameter for many agricultural practices. Since it may present spatial variability within vineyards, it is very interesting monitoring it in an objective repeatable way. Considering the possibility of using on-the-go sensors such as MTLS within an agricultural plot, it is necessary to set a proper length of the row to be scanned at each sample point for a reliable operation of the scanner. Three different row length sections of 0.5, 1, and 2 m have been tested. Data analysis has shown that models required to estimate LAI differ significantly depending on the scanned length of the row; the model required to estimate LAI for short sections (0.5 m) is different from that required for longer sections (1 and 2 m). Of the two models obtained, we recommend using MTLS for scanning row length sections of 1 m because the practical use of the sensor in the field is simplified without compromising the results (there is little variation in the model when the row length section changes from 1 to 2 m). In addition, a sufficient number of sampling points is obtained to support a map of the LAI. Linear regression models using as explanatory variable the tree area index, obtained from the data provided by the scanner, are used to estimate the LAI.     

云南葡萄架式和树形应用调查分析

通过对云南葡萄主产区的葡萄栽培架式和树形应用的调查分析,对架式和树形与葡萄生长发育、产量、果实品质和用工量的关系有了初步的认识。同时从大理州宾川县的架式和树形改造中汲取了一些值得学习借鉴的经验,对今后类似的葡萄园改造具有一定帮助。     

Relevance of sink-size estimation for within-field zone delineation in vineyards

Source to sink size ratio, i.e.: the relative abundance of photosynthetically active organs (leaves) with regards to photosynthate demanding organs (mainly bunches), is widely known to be one of the main drivers of grape oenological quality. However, due to the difficulty of remote sink size estimation, Precision Viticulture (PV) has been mainly based on within-field zone delineation using vegetation indices. This approach has given only moderately satisfactory results for discriminating zones with differential quality. The aim of this work was to investigate an approach to delineate within-vineyard quality zones that includes an estimator of sink size in the data-set. The study was carried out during two consecutive seasons on a 4.2 ha gobelet-trained cv. ‘Tempranillo’ vineyard. Zone delineation was performed using Normalized Difference Vegetation Index (NDVI), soil apparent electrical conductivity (EC_a) and bunch number (BN) data. These variables were considered separately, in pairs, or the three altogether, using fuzzy k-means cluster analysis for combinations. The zones delineated based on single variables did not allow a sufficient discrimination for grape composition at harvest, NDVI being the only variable that by itself resulted in zones that to some extent differed in grape composition. On the contrary, when two variables were combined, discrimination in terms of grape composition improved remarkably, provided the sink size estimation variable (BN) was included in the combination. Lastly, the combination of the three variables yielded the best discriminating zoning, improving slightly on those provided by NDVI + BN and EC_a + BN combinations. Thus, the relevance of including a variable related to sink size (in this case the number of bunches per plant) has been confirmed, which makes its consideration highly advisable for any PV work aiming at zone delineation for grape quality purposes.     

Evaluation of vegetation indices and apparent soil electrical conductivity for site-specific vineyard management in Chile

Spatial variability of Chilean vineyards, in terms of yield and quality, is high, which fully justifies site-specific management, particularly differential harvest. In this study, the most common zoning tools (NDVI and ECa measurements) were evaluated and compared. Comparisons also included a calibrated GVI. Two contrasting large field experiments (pruning, irrigation, and N fertilization treatments) were established in vineyards to (1) evaluate two vegetation indices: (i) a non-calibrated airplane-based NDVI and (ii) calibrated satellite-based GVI and to (2) evaluate the ECa measurements. The GVI was also assessed at the commercial level, in different vineyards and valleys. The GVI was more sensitive in discriminating grape yields and quality while the NDVI failed to adequately sense vigor patterns and fruit quality in the more homogeneous site. Thus, a calibrated GVI can be recommended as a better tool than NDVI for defining management zones as well as making spatial and temporal comparisons among fields and seasons. In general, ECa explained few differences in the alluvial soil properties and did not predict differences in plant vigor as measured by either vegetation indices, therefore ECa by itself was not a good estimator of the most commonly measured soil properties for establishing management zones in these fields with low variability in terms of EC and other soil characteristics.     

一种新型葡萄越冬埋藤机的设计

针对中国北方葡萄冬季越冬埋藤作业以人工作业为主,劳动强度大、效率低等问题,设计了一种新型葡萄埋藤机。结果表明,该机埋藤质量好、通用性好、不易堵塞且覆土后的葡萄无冻伤和风干现象;覆土厚度平均33.7 cm,宽度105.9 cm,抛土距离平均为51.1 cm,取土宽度平均为98.3 cm,挖沟距根部距离平均53.5 cm,可满足葡萄冬季埋藤的农艺要求。     

Near infrared spectroscopy as a tool for intensive mapping of vineyards soil

The wine industry has always been particularly interested in the influence of the terroir characteristics on the features of a wine. Over the past few years, a growing interest has spurred on the mechanisms by which a particular soil influences the vine’s growth, grape variety characteristics and ultimately wine quality. Near-infrared spectroscopy (NIRS) is a rapid, non-destructive, low-cost and robust analytical method for chemical and physical property determination. Its use for soil characterization, discrimination and compound determination is rapidly increasing. In this work, NIRS data were collected in two vineyards, one in the Dão Wine Region (centre of Portugal) and one in the Vinhos Verdes Wine Region (North of Portugal) previously characterized in terms of soils. Wet, dried and dried-ground soil samples collected from specific vineyard locations were scanned on a Fourier-transform near infrared spectrometer (FTLA 2000, ABB, Quebec, Canada) in diffuse reflectance mode. Spectra were analysed with chemometric tools, namely principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). Results revealed that dried, ground soil samples gave better results, but not substantially so when compared with wet or dried samples. Discriminant models showed that the NIRS method is able to discriminate the different vineyard soil types, reproducing very accurately the mapping generated by pedology methods. Variations within the same soil type (present at different locations in the vineyard) were also detected by NIRS. The NIRS technology was shown to be suitable for correlating, complementing and perhaps eventually replacing costly, time-consuming vineyard soil mapping methods.     

太原市尖草坪区葡萄园测土配方施肥技术

太原市尖草坪区自然条件优越,生产的葡萄品质好,深受市场欢迎。葡萄年产量达1 200万kg,是尖草坪区重要的产业支柱。通过对该地葡萄园基本情况和农户施肥情况进行调查,分析了该区葡萄园施肥中存在的问题,结合果园土壤化验,在试验示范基础上,提出了尖草坪区葡萄园的施肥原则和不同品种的施肥方案。     

Comparison of passive and active canopy sensors for the estimation of vine biomass production

Recent advances in optical designs and electronic circuits have allowed the transition from passive to active proximal sensors. Instead of relying on the reflectance of natural sunlight, the active sensors measure the reflectance of modulated light from the crop and so they can operate under all lighting conditions. This study compared the potential of active and passive canopy sensors for predicting biomass production in 25–32 randomly selected positions of a Merlot vineyard. Both sensors provided estimates of the normalized difference vegetation index (NDVI) from a nadir view of the canopy at veraison that were good predictors of pruning weight. Although the red NDVI of the passive sensors explained more of the variation in biomass (R ² = 0.82), its relationship to pruning weight was nonlinear and was best described by a quadratic regression (NDVI = 0.55 + 0.50 wt−0.21 wt²). The theoretically greater linearity of the amber NDVI-biomass relationship could not be verified under conditions of high biomass. The linear correlation to stable isotope content in leaves (¹³C and ¹⁵N) provided evidence that canopy reflectance detected plant stresses as a result of water shortage and limited fertilizer N uptake. Thus, the canopy reflectance data provided by these mobile sensors can be used to improve site-specific management practices of vineyards.