Carlos Poblete-Echeverría

Stellenbosch University | SUN · Department of Viticulture and Oenology

Apple scab, caused by Venturia inaequalis, is the most common fruit and foliar disease in commercial apple production worldwide. Early in the production season, preventative contact fungicide sprays are essential for protecting highly susceptible continuously unfolding and expanding young leaves. In South Africa, mancozeb is a key contact fungicide...

Vineyard yield estimation provides the winegrower with insightful information regarding the expected yield, facilitating managerial decisions to achieve maximum quantity and quality and assisting the winery with logistics. The use of proximal remote sensing technology and techniques for yield estimation has produced limited success within viticultu...

The determination of internal maturity parameters of table grape is usually done destructively using manual methods that are time-consuming. The possibility was investigated to determine whether key fruit attributes, namely, total soluble solids (TSS); titratable acidity (TA), TSS/TA, pH, and BrimA (TSS – k x TA) could be determined on intact table...

Remote Sensing (RS) allows the estimation of some important vineyard parameters. There are several platforms for obtaining RS information. In this context, Sentinel satellites are a valuable tool for RS since they provide free and regular images of the earth’s surface. However, several problems regarding the low-resolution of the imagery arise when...

The use of temperature as an indicator of water stress is gaining attention in agriculture. However, the need for reference temperature measurements in the field (Twet and Tdry) for normalization purposes (calculation of the crop water stress index - CWSI) inhibits the practical implementation of this technique. Therefore, in this study, two new mo...

Accurately and automatically estimating vineyard yield is a significant challenge. This study focuses on grape bunch counting in commercial vineyards using advanced deep learning techniques and object detection algorithms. The aim is to overcome the limitations of conventional yield estimation techniques, which are labour-intensive, costly, and oft...

Knowledge of the spatial variation in vine yield at different scales is crucial for the wine business, and combined with estimations of vine size variability enables within-block mapping of vegetative-reproductive balance. Remote sensing combined with other data that excludes field sampling appears as an optimal approach for yield estimation for a...

Soil water content is a key factor in the climate–soil–vegetation system. Climate and weather conditions define the amount of water and energy available, impacting the evapotranspiration process. The objective was evaluating the effect of soil water content on soil temperature and heat storage in a drip-irrigated potato crop (Solanum tuberosum L. v...

Water stress is a major factor affecting grapevine yield and quality. Standard methods for measuring water stress, such as midday stem water potential (ΨSWP), are laborious and time-consuming for intra-block variability mapping. In this study, we investigate water status variability within a 2.42-ha commercial Cabernet Sauvignon block with a standa...

Resumen La estimación del rendimiento es muy importante para la industria vitivinícola, ya que proporciona información útil para la gestión de viñedos y bodegas. Los efectos del cambio climático, como el aumento de las temperaturas y la menor disponibilidad de agua, pueden afectar a los componentes del rendimiento del viñedo. En general, la previsi...

Nowadays, diseases are one of the major threats to sustainable viticulture. Manual detection through visual surveys, usually done by agronomists, relies on symptom identification and requires an enormous amount of time. Detection in field conditions remains difficult due to the lack of infrastructure to perform detailed and rapid field scouting cov...

Group-living animals that live in complex social systems require effective modes of communication to maintain social cohesion, and several acoustic, olfactory and visual signaling systems have been described. Individuals need to discriminate between in- and out-group odour to both avoid inbreeding and to identify recipients for reciprocal behaviour...

The evapotranspiration (ET) process is an essential component in many agricultural water management, and its estimation is even more determinant when crops are grown under water-limited environments. The traditional canopy resistance (r_c) approaches were evaluated to simulate potato evapotranspiration (ETcp) using the original Penman-Monteith equa...

The evapotranspiration (ET) process is essential for many agricultural water management studies and its partitioning into soil evaporation (E) and plant transpiration (T) is key for optimizing the irrigation water use under scarce water resources. A field experiment was carried out on a drip-irrigated potato crop (var. Puyehue INIA) during the maxi...

The determination of bunch features that are relevant for bunch weight estimation is an important step in automatic vineyard yield estimation using image analysis. The conversion of 2D image features into mass can be highly dependent on grapevine cultivar, as the bunch morphology varies greatly. This paper aims to explore the relationships between...

The determination of bunch features that are relevant for bunch weight estimation is an important step in automatic vineyard yield estimation using image analysis. The conversion of 2D image features into mass can be highly dependent on grapevine cultivar, as the bunch morphology varies greatly. This paper aims to explore the relationships between...

A few decades ago, farmers could precisely monitor their croplands just by walking over the fields, but this task becomes more difficult as farm size increases. Precision viticulture can help better understand the vineyard and measure some key structural parameters, such as the Leaf Area Index (LAI). Remote Sensing is a typical approach to monitori...

Table grape browning is a complex physiological disorder that occurs during cold storage. There is a need to investigate novel and innovative ways to manage the problem that hampers the progressive and sustainable growth of table grape industries. Given the complex nature of the browning phenomenon, techniques such as near-infrared (NIR) spectrosco...

Improving wine composition is a critical factor for the wine industry. Phenolic compounds play an important role in wine composition contributing to its organoleptic characteristics. Although several factors can influence the phenolic concentration, plant water status in particular has shown to have a direct impact on the phenolic compounds. It is...

Accurate quantification of the spatial variation of canopy size is crucial for vineyard management in the context of Precision Viticulture. Biophysical parameters associated with canopy size, such as Leaf Area Index (LAI), can be estimated from Vegetation Indices (VI) such as the Normalized Difference Vegetation Index (NDVI), but in Vertical-Shoot-...

Research and innovation activities in the area of sensor technology can accelerate the adoption of new and emerging digital tools in the agricultural sector by the implementation of precision farming practices such as remote sensing, operations, and real-time monitoring. The agricultural industry has been greatly affected by climate change; therefo...

Vineyard yield estimation is a fundamental aspect in precision viticulture that enables a better understanding of the inherent variability within a vineyard. Yield estimation conducted early in the growing season provides insightful information to ensure the best fruit quality for the maximum desired yield. Proximal sensing techniques provide non-d...

In table grape production it is critical to have an accurate method to assess the external and internal quality of the fruits. Many fruit quality attributes that affect consumer acceptance and price are still tested using traditional approaches, which are either subjective or time-consuming. In this sense, Near-Infrared spectroscopy has been succes...

According to ESA (European Space Agency), Remote Sensing is a way of collecting and analysing data to get information about an object, without the instrument used to collect the data in direct contact with the object. This tool has proved its usefulness in a wide range of fields, including agriculture, a field in which the use of multispectral imag...

Research and innovation activities in the areas sensor technology can accelerate the adoption of new and emerging digital tools in the agricultural sector by the implementation of precision farming practices such as remote sensing, operations, and real-time monitoring. The agricultural industry has been greatly affected by climate change; therefore...

The surface renewal method (SR) allows estimating the sensible heat flux (H) using high-frequency thermocouples. Traditionally, SR has been compared and calibrated using standard instruments such as the Eddy covariance system (EC). Calibration involves correcting H measured with SR (H' SR) by means of the calibration factor (α). However, several st...

Delivering table grapes that are of exceptional quality and free of any defects or disease to different export markets is vital for table grape industries. After harvest, table grapes (non-climacteric fruit) do not improve, and maintenance of the quality achieved in the vineyard up to retail shelves remains a challenge. Currently, visual inspection...

Fruit export is an important economic activity for Chile. Therefore, high productivity and quality fruit is a must in order to succeed in the business. A 6-year project was carried out to assess apple cultivars (‘Galaxy’, ‘Brookfield®Gala’, ‘Super Chief’, ‘Fuji Raku Raku’, ‘Braeburn’, ‘Granny Smith’, and ‘Cripps Pink’) and rootstock's (M.M.106 and...

Many irrigation strategies have been proposed in olive orchards to overcome both increasing water scarcity and competition for water with other sectors of society. However, threshold values of stomatal conductance (gs) and stem water potential (Ψstem) for use in designing deficit irrigation strategies have not yet been adequately defined. Thus, an...

Abstract: Pruning Weight (PW) has been widely used by viticulturists as an indicator of vine balance. Its estimation provides useful information for obtaining quality grapes in the succeeding season. Within-season, an estimation of PW using Remote Sensing (RS) may help regulate crop load and canopy management to ensure an adequate balance. Consider...

Canopy temperature (Tc) by thermal imaging is a useful tool to study plant water status and estimate other crop traits. This work seeks to estimate grain yield (GY) and carbon discrimination (∆ 13 C) from stress degree day (SDD = Tc − air temperature, Ta), considering the effect of a number of environmental variables such as the averages of the max...

Leaf area per unit surface (LAI—leaf area index) is a valuable parameter to assess vine vigour in several applications, including direct mapping of vegetative–reproductive balance (VRB). Normalized difference vegetation index (NDVI) has been successfully used to assess the spatial variability of estimated LAI. However, sometimes NDVI is unsuitable...

The identification of Chinese medicinal plants has relied in the past on ampelographic manual assessment by experts. However, more recently machine learning algorithms for pattern recognition, have been successfully applied to leaf recognition in other plant species. These new tools make the classification of Chinese medicinal plants easier, more e...

Ripening heterogeneity of Hass avocados results in inconsistent quality fruit delivered to the triggered and ready to eat markets. This research aimed to understand the effect of a heat shock (HS) prior to controlled atmosphere (CA) storage on the reduction of ripening heterogeneity. HS prior to CA storage reduces more drastically the ripening hete...

To overcome the environmental changes occurring now and predicted for the future, it is essential that fruit breeders develop cultivars with better physiological performance. During the last few decades, high-throughput plant phenotyping and phenomics have been developed primarily in cereal breeding programs. In this study, plant reflectance, at th...

Rind biochemical properties play major roles in defence mechanisms against the incidence of rind physiological disorders of citrus fruit during cold storage. Hence, multivariate calibration models were developed to rapidly and non-destructively determine rind biochemical properties of citrus fruit from visible to near-infrared (Vis/NIR) spectra acq...

Commercial harvest maturity of 'Hass' avocado fruit is estimated based on dry matter content (DM). Typically, a few samples representing the entire orchard are destructively analysed using time-consuming procedures such as oven or freeze drying the fruit's mesocarp. However, the maturity parameter of avocado, that is known to have a direct link to...

In the Chilean viticultural industry, Carménère is considered an emblematic cultivar that is cultivated mainly in arid and semi-arid zones. For this reason, it is necessary to use precise irrigation scheduling for improving water use efficiency (WUE), water productivity (WP), yield and wine quality. This study evaluated the effects of three deficit...

The application of computer vision algorithms and chemometric fingerprinting using near-infrared spectrometry (NIR) of plant leaves, offer enhanced capabilities for ampelography by providing more accurate methods to discriminate leaves based on morphological parameters, and chemometrics, respectively. This paper showed that machine learning algorit...

Table grapes are climacteric fruit and the quality will not improve after harvest. The quality, therefore, should be maintained from harvest, through post-harvest and finally the retail shelf. However, due to the multi-faceted nature of table grape quality, it is very difficult to put a monitoring tool in place, which can measure both the chemical...

Hass avocado ripening heterogeneity generates logistics problems to importers and ripeners due to higher labour costs, inconsistent quality delivery and postharvest losses. The main aims of this research were: (i) to evaluate two postharvest pre-treatments (nitrogen shock N2 and heat shock) prior controlled atmosphere (CA) on reduction of ripening...

A study was carried out to calibrate and validate the aerodynamic temperature method for estimating the spatial variability of the sensible (H) and latent (LE) heat fluxes over a drip-irrigated merlot vineyard located in the Maule Region, in Chile. For this study, measurement of energy balance components and meteorological data were collected from...

The use of Unmanned Aerial Vehicles (UAVs) in viticulture permits the capture of aerial Red-Green-Blue (RGB) images with an ultra-high spatial resolution. Recent studies have demonstrated that RGB images can be used to monitor spatial variability of vine biophysical parameters. However, for estimating these parameters, accurate and automated segmen...

Actual evapotranspiration values (ETa) are frequently obtained using the approach that combines reference evapotranspiration (ETo) and empirical crop coefficient (Kc) proposed by FAO. However, several studies carried out in grapevines showed that Kc values proposed by FAO do not agree with those obtained experimentally. Therefore, a verification of...

A field experiment was carried out to develop a remote sensing energy balance (RSEB) algorithm for estimating olive evapotranspiration (ET) using multispectral and thermal sensors placed aboard an unmanned aerial vehicle (UAV). During February and March 2014, measurements of micrometeorological variables, surface energy balance components and remot...

To evaluate the energy balance components and actual evapotranspiration (ETa), measurements of net radiation (Rn), sensible heat flux (HEC), soil heat flux (G), latent heat flux (LEEC) and reference evapotranspiration (ETo) were carried out during the 2009/10 and 2010/11 growing seasons over an uniform superintensive 'Arbequina' olive orchard locat...

Water management and improving of water use efficiency (WUE) are very important issues on vineyards grown in semi-arid conditions. Stem water potential (Ψstem) is one of the most common tools to evaluate the water status in vineyards. However, some researchers have indicated that the water stress integral (SIΨ) could be a better parameter for expla...

The crop water stress index (CWSI) was developed as a normalized index to quantify stress and overcome the effects of other environmental parameters affecting the relationship between stress and plant temperature. This index has been widely used for crop water status monitoring. Nowadays CWSI can be determined by different methodologies being the m...

This article describes public, free software that provides efficient exploratory analysis of high-resolution spectral reflectance data. Spectral reflectance data can suffer from problems such as poor signal to noise ratios in various wavebands or invalid measurements due to changes in incoming solar radiation or operator fatigue leading to poor ori...

Aerial and terrestrial thermography has become a practical tool to determine water stress conditions in vineyards. However, for proper use of this technique it is necessary to consider vine architecture (canopy zone analysis) and image thresholding approaches (determination of the upper and lower baseline temperature values). During the 2014–2015 g...

Inferring foliar temperatures is motivated by the high cost related to measure each plant's temperatures in a vineyard. Foliar temperature is correlated with the plants water potential, which allows farmers to take irrigation decisions. In order to deal with this situation, we utilized information obtained from several temperature infrared sensors...

A field experiment was carried out to implement a remote sensing energy balance (RSEB) algorithm for estimating the incoming solar radiation (Rsi), net radiation (Rn), sensible heat flux (H), soil heat flux (G) and latent heat flux (LE) over a drip-irrigated olive (cv. Arbequina) orchard located in the Pencahue Valley, Maule Region, Chile (35°25′S;...

The planting of sugarcane crops has expanded in the last decade in the southeast of Brazil, mainly due to its use for biofuel production, such as ethanol. This expansion in the State of São Paulo has occupied land that was previously used for cattle production. The change in land use affects soil and water through changes in ground cover and distur...

The main goal of this research was to estimate the actual evapotranspiration (ETc) of a drip-irrigated apple orchard located in the semi-arid region of Talca Valley (Chile) using a remote sensing-based soil water balance model. The methodology to estimate ETc is a modified version of the Food and Agriculture Organization of the United Nations (FAO)...

Irrigation scheduling is critical for vineyards and olive orchards, since it directly affects yield and fruit composition. Regulated deficit irrigation (RDI) strategies have been applied on both crops with positive results in the past. However, to successfully regulate stress levels, it is necessary to have accurate measurements of plant water stat...

To evaluate the partitioning of net radiation (Rn) and actual evapotranspiration (ETa), measurements of Rn, sensible heat flux (H), soil heat flux (G), latent heat flux (LE), reference evapotranspiration (ETo), transpiration (Tp) and soil evaporation (Es) were taken during the 2009/2010 and 2010/2011 growing seasons on a flat and uniform olive (cv....