9 research outputs found
Developing crop canopy model for irrigation of high-density olive groves by using UAV imagery
No full textPlant architecture is a key issue in understanding olive tree water needs. The aim of this study is to evaluate water requirements of a high-density olive grove by coupling an agro-hydrological model with UAV-based, high-resolution 2D imagery and 3D structure from motion (SfM) reconstruction. Three planting densities (1670, 1000, 500 trees ha-1) were drip irrigated according to two irrigation regimes. Evapotranspiration was estimated using FAO56 and FAO66-modified approaches. FAO66 input data (canopy volume and coverage) were quantified using manual ground-based surveys, 2D imagery and 3D SfM reconstruction. 2D imagery showed better relationships to ground-based area and volume estimates than the 3D SfM approach. Moreover, coupling the ET model with 2D data accurately predicted crop water needs
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Opportunities for Urban Agriculture: Balcony Hydroponics in Thessaloniki
No full textThe economic crisis currently in Greece has led to adverse health impacts as people are more frequently choosing inexpensive foods over fresh vegetables. Local residents of Thessaloniki would like to participate in urban agriculture to grow their own fresh vegetables, but suitable land is scare in this densely populated metropolis. We evaluated balcony hydroponics within Thessaloniki, in collaboration with Dr. Athanasios Gertsis of Perrotis College. Utilizing an iterative, human-centered design approach, we devised three hydroponic systems that are cost, time and space efficient. These designs provide potential users with a variety of options regarding aesthetics and function
Cotton (Gossypium hirsutum l.) plant water status as a function of soil water supply and evaporative demand in a semiarid environment
No full textThe Southern High Plains of Texas (SHPT) representing a major cotton iGossypium hirsutum L.) growing area of the United States and the world is characterized as a semiarid environment with inadequate rainfall to meet the high evaporative demand. Soil water content and evaporative demand interact with the plant to determine tissue water status. Leaf water potential (øL), the primary indicator of plant water status, is commonly used in crop simulation models to determine growth rates and yield potential. Functional relationships between cotton øL and soil water supply and evaporative demand have not been well-defined for cotton grown in the SHPT area. A field experiment was conducted for two years to determine the relationship between *FL of cotton plants as a function of Ts, plant size and atmospheric factors affecting evaporative demand. Three irrigation levels (0%, 50% , and 100%) of replacement of water used as evapotranspiration (ETa) were used to provide a range of soil water supplies in two soil types (Amarillo loamy sand and Pullman clay loam), øL, soil water supply as indicated by soil matric potential Q^s), air temperature, relative humidity, incident and absorbed solar radiation, and plant growth were monitored throughout the growing season. Correlation and stepwise multiple regression were used to investigate and develop relationships between øL and øs and the evaporative demand. The variables highly correlated with øL were øs, and daily (24 hrs) average air temperatures (Tavg) as the most effective parameters of the evaporative demand. The relative contribution of each parameter on the variation explained for øL was shown not to be sensitive of plant growth stage as indicated by LAI ranges, but was sensitive to existing soil water supply. The overall effect of soil water supply was more dominant than the evaporative demand across the entire period of data measurement and within all LAI ranges. Crop growth rate (CGR), mainstem elongation rate (MER) and leaf area growth rate (LAGR) declined sharply when øL declined from its non-limiting conditions of -1.2 MPa to -1.6 MPa. From -1.6 MPa to -2.5 MPa øL growth rates continued to decline but at a slower rate. Essentially zero growth of all parameters was observed when øL dropped below -2.7 MPa. Results also indicated no differential sensitivity of reproductive versus vegetative growth rates to declining øL. In general, for cotton grown in the SHPT area, plant water status should be maintained above -1.6 MPa for maximum growth
Precision Agriculture Applications in a High Density Olive Grove Adapted for Mechanical Harvesting in Greece
No full textAbstractWorldwide olive production recently has undergone major changes in terms of harvesting technologies and planting densities. A new educational, research and exhibition olive grove was established at Perrotis College, Greece in 2010 to evaluate new production systems under a variety of planting densities and major input treatments for two of the most commonly used olive varieties globally, under high density palnting systems adapted for mechanical harvesting. Precision agriculture practices were used in this olive grove, to identify possible “zones of variation” for yield, crop reflectance using the handheld GreenSeeker® NDVI sensor and for soil moisture and electrical conductivity. The results are presented herein for the second year after planting and they indicated distinctive zones of variability for the measured characteristics. These zones will be considered and further validated in the current season, to provide alternative management practices for optimization of olive production and combined with additional soil and agronomic parameters
Growing Lettuce (Lactuca sativa L.) in Floating Disk Systems Under Variable and High Salinity Ranges in Water Enriched with Nanobubbles
No full textHydroponic systems, which use commercial hydroponics technologies, are cheaper and easier to maintain than traditional farming methods in soil. The objective of this study was to evaluate various salinity ranges (E.C.i from 1 dS/m to 14 dS/m) in water enriched with nanobubbles (NBs) for the growth and productivity of lettuce plants in a floating disk hydroponic system. This research study investigated how using floating disks in a greenhouse with a nanobubble (NB) generator may affect lettuce’s (Lactuca sativa L.) morphological and physiological responses to salt stress. The goal of this experiment was to examine the results of the influence of NB and non-NB treatments on agronomic traits and yield. The results indicated that the NB device is an innovative and very effective technology for sustainable lettuce production under a high-salinity nutrient solution. This device presents a valuable solution to the global issue of the increased salinity of irrigation water
Rapid Nondestructive Postharvest Potato Freshness and Cultivar Discrimination Assessment
No full textBackground: Quality and safety of potato is both cultivar and postharvest management dependent. The precise assessment of freshness and cultivar are complex tasks requiring time-consuming, expensive, and destructive techniques. Method: Potatoes from three commercial cultivars were stored for 5 months at 5 °C. Color and chlorophyll fluorescence were recorded, Red-Green-Blue (R-G-B), Red-Green-Near infrared (R-G-NIR) and Red-Blue-Near infrared (R-B-NIR) digital images, as well as hyperspectral images were acquired both on the external periderm of the tuber and in the inner flesh part. Partial least square regression (PLSR) and discriminant analysis, combined with feature selection techniques were implemented, in order to assess the potato freshness and to classify them into the respective genotypes. Results: The PLSR analysis of visible/near infrared (Vis/NIR) spectra reflectance most reliably predicted potato freshness, with a cross-validated regression coefficient equal to 0.981 and 0.947, as determined by external or internal measurements, respectively. Variance inflation factor, variable importance scores, and genetic algorithms identified specific wavelength regions that mostly affected the accuracy of the model in terms of strongest regression and lowest collinearity and root mean cross validation error. Conclusions: Vis/NIR spectra reflectance data from the skin of the potato tubers may be reliably used in the assessment of postharvest storage life, as well as in the cultivar discrimination process
Nutritional composition changes in bell pepper as affected by the ripening stage of fruits at harvest or postharvest storage and assessed non‐destructively
No full textHow to eliminate obstacles of IWM implementation into cropping systems in South East Europe
No full textIn this presentation, the outcomes of a specific EWRS regional meeting organized by the Working
Group »Optimization of Herbicide Use in an IWM context« are documented. Data were obtained
by a questionnaire survey and a face-to-face group discussion. The idiosyncratic structure and
systemic nature of IWM systems, as compared with other IPM systems, draws on many strategies
with a combination and integration of single weed management tactics at temporal and spatial
scale. The questionnaire included queries with multiple-choice predefined answers and left space
for open answers. All those were given a significance score value (1 to 5). During the meeting,
the face-to-face group discussion was aimed on the fine elaboration, sorting and ranking of the
major weed problems and obstacles for IWM systems implementation in South East European
countries. Regional South East countries address the IWM by different approaches based on their
status towards EU. Countries outside the EU, have set up voluntary public and private entities to
promote IWM whereas Member States of the EU have implemented the Sustainable Use Directive
(Dir. 2009/128/EC) aiming to regulate use of pesticides (herbicides, in particular), and are required to
set up National Plans. Regional cropping systems frequently face similar (more or less) major weed
problems and IWM challenges, research needs and priorities and extension services upgrades to
tackle IWM implementation. Identifying the current obstacles and propose measures to eliminate
them would boost national efforts as they could benefit from a common IWM framework and
transnationally approaches
