Optical devices evaluation for diagnosis of Plasmopara viticola

Remote sensing (RS) is the most widely adopted technique for crop monitoring in precision viticulture (PV).  Recent research looks at the development of proximal sensing technologies alternative to RS.  The present work considers the possible use of proximal sensing optical devices for diagnosis in vineyard; in particular, we evaluated the GreenSeeker RT100 and the Crop Circle (two commercial optical sensors) in detecting different levels of grapevine downy mildew symptoms.  The analysis was conducted on vine leaves that had been picked from plants of cv.  Cabernet Franc infected by Plasmopara viticola.  Leaves were divided into homogeneous infection classes and then analyzed through the optical devices and a portable Vis/NIR (visible/near infrared) spectrophotometer used as tester.  Data showed a linear relation between the percentage of symptomatic leaf area and normalized difference vegetation index NDVI calculated through the two optical sensors (R2 = 0.708 for GreenSeeker; R2 = 0.599 for Crop Circle; R2 = 0.950 for the spectrophotometer).  The regression obtained for GreenSeeker is more significant than the regression obtained for Crop Circle.  This fact suggests a greater capability of GreenSeeker than Crop Circle in detecting different disease levels and its possible use in diagnosis application in vineyard.Keywords: precision viticulture, diagnosis, NDVI, proximal sensing, optical devices 

Comparing commercial optical sensors for crop monitoring tasks in precision viticulture.

The emergence of precision agriculture technologies and an increasing demand for higher quality grape products has led to a growing interest in Precision Viticulture. Actually, cultural monitoring is the most important application in PV systems: it requires specific technologies able to investigate the cultural conditions. To this aim, typically remote sensing surveys are adopted. These, anyhow, involve technical, economical and organisational barriers hampering a wide diffusion of their application. In order to overcome these problems, it would be necessary to substitute and/or integrate remote sensing information with alternative ground sensing technologies, to be employed directly inside the vineyard. This paper considers a commercial optical sensor, the GreenSeeker, useful in ground sensing surveys, and it compares its performances in monitoring vine with results obtained by a multispectral digital camera used as a tester. The experimentation was carried out in a greenhouse, on an artificial row including 15 grapevines (Cabernet Sauvignon variety). In front of the row, it was fixed a metallic rail gauge in order to permit a longitudinal movement of the Greenseeker sensor. Each plant was investigated at three different heights with a 5 s data time acquisition. Simultaneously, photos of the same grapevine were took by a multispectral digital camera, in order to obtain NDVI values through image analysis. The multispectral digital camera, normally used for remote sensing survey in agriculture, was considered as a test. Results demonstrate a strength correlation (R2 = 0.97) between the NDVI values measured through the two methods. This shows the same behaviour of the two tools, according to crop vigour and stress conditions induced into the plants. Consequently the GreenSeeker can be considered as a suitable solution for cultural monitoring in viticulture

COMPARING COMMERCIAL OPTICAL SENSORS FOR CROP MONITORING TASKS IN PRECISION VITICULTURE

The emergence of precision agriculture technologies and an increasing demand for higher quality grape products has led to a growing interest in Precision Viticulture. Actually, cultural monitoring is the most important application in PV systems: it requires specific technologies able to investigate the cultural conditions. To this aim, typically remote sensing surveys are adopted. These, anyhow, involve technical, economical and organisational barriers hampering a wide diffusion of their application. In order to overcome these problems, it would be necessary to substitute and/or integrate remote sensing information with alternative ground sensing technologies, to be employed directly inside the vineyard. This paper considers a commercial optical sensor, the GreenSeeker, useful in ground sensing surveys, and it compares its performances in monitoring vine with results obtained by a multispectral digital camera used as a tester. The experimentation was carried out in a greenhouse, on an artificial row including 15 grapevines (Cabernet Sauvignon variety). In front of the row, it was fixed a metallic rail gauge in order to permit a longitudinal movement of the Greenseeker sensor. Each plant was investigated at three different heights with a 5 s data time acquisition. Simultaneously, photos of the same grapevine were took by a multispectral digital camera, in order to obtain NDVI values through image analysis. The multispectral digital camera, normally used for remote sensing survey in agriculture, was considered as a test. Results demonstrate a strength correlation (R2 = 0.97) between the NDVI values measured through the two methods. This shows the same behaviour of the two tools, according to crop vigour and stress conditions induced into the plants. Consequently the GreenSeeker can be considered as a suitable solution for cultural monitoring in viticulture

TEST OF GROUND-SENSING DEVICES FOR MONITORING CANOPY VIGOUR AND DOWNY MILDEW PRESENCE IN VINEYARDS: FIRST QUALITATIVE RESULTS

This paper considers the possibility to use ground sensing technologies that can be employed directly in vineyards. The aim of this work is to evaluate contemporarely the canopy health and vigour status of vines through the use of a mobile monitoring system; this, in order to investigate the possibility to realize a pathological diagnosis in vineyards. To achieve this objective optical and analogue devices were tested: a) GreenSeeker RT100, a commercial optical device calculating NDVI in real time; b) ultrasonic sensors for canopy thickness estimation. A DGPS receiver was employed for geo-reference data collected while travelling in the vineyards. Tests were conducted in a commercial vineyard which included rows treated and non-treated with agrochemicals. Data coming from the automatic monitoring were compared to manual morphological and physiological observations carried out to characterize the phytosanitary status of the canopy. Optical data were processed in order to obtain NDVI maps. They clearly showed differences in canopy vigour evolution in the two examined groups, and low vegetative vigour in areas infected by Plasmopara viticola (as confirmed by manual assessment). Maps of percentage infection index (I%I) were produced according to pathological manual survey results. The comparison between I%I and NDVI maps confirmed, at a qualitative level, the real vine phytosanitary status. The integration of UCT and NDVI values allows the identification of diseased vineyard areas among zones presenting critical vegetation conditions

Life cycle assessment: an application to poplar for energy cultivated in Italy

The development of the bioenergy sector has led to an increasing interest in energy crops. Short rotation coppices (SRC) are forestry management systems in which fast-growing tree species are produced under intensive cultivation practices to obtain high wood chips yields. In Italy, most SRC plantations consist of poplar biomass-clones. SRC plantations can be carried out with different management systems with diverse cutting times; consequently, the cultivation system can be crucial for attaining high yields depending on: i) short and ii) medium cutting frequency. Nowadays, the larger part of Italian SRC is based on 2-year cutting short rotation forestry (SRF) but the best quality of wood chips is linked to 5-year plantation medium rotation forestry (MRF). This work compares an SRF and an MRF poplar plantation located in the Po Valley in northern Italy. In particular, a life cycle assessment (LCA) was carried out to evaluate their energy demand and greenhouse gas emissions. The LCA software SimaPro 7.10 was used to create the LCA model and to assure an accurate impact assessment calculation. The analysis shows several differences between MRF and SRF in terms of fertiliser requirements and intensive agricultural activities. Results highlight that MRF produces a more sustainable wood chip production than SRF according to energy and environmental concerns. Furthermore, <em>hot spots</em> were identified in both SRF and MRF due to the high energy consumption and the related emissions. These <em>hot spots </em>were: i) mineral fertilisation; ii) mechanical weed-control; iii) harvesting and biomass transport