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Applicability of precision weed detection technologies
Published February 10, 2013

...5); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">In an agricultural field or horticultural plantation, weeds compete with cultivated plants for water and nutrients. The transpirated water by the weeds is needed to be replaced, which saddles surplus costs on the farmer, which could reduce the profitability of crop production. The aim of the precision plant protection system is to protect cultivated plants by applying site-specific technologies and optimized herbicides combination and methods, without environmental damage. The first step of precision weed control is the scouting for weeds. Traditional and modern (passive and active remote sensing) weed surveying technologies are available to detect weeds. The examination was carried out in an intensive apple orchard with drip irrigation system, protected by hail net of the Study and Regional Research Farm of the University of Debrecen near Pallag. The spectral-based weed detection was worked out by the Tetracam ADC broadband multispectral camera and the GreenSeeker 505 vegetation indexmeter. A strong correlation observed between vegetation indices and weed coverage. Based on the collected data, weed maps are created in appropriate software environment, thus the spatial distributions of the weeds are determined. The species level discrimination and the recognition of weed structural parameters were executed based on the 3D point cloud data by Leica ScanStation C10 laser scanner.

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Development of precision apple production technologies in Institute of Water and Environmental Management
Published July 18, 2012

From the precision agriculture point of view, by the rapid development of the investigated technological elements – global positioning system (GPS), remote sensing (RS), global information system (GIS) – the number of services, which were not available in the past, because of their speed, complexity or price are increasing. The high accurac...y high-tech instruments provide opportunity to elaborate several fruit production technologies, which aim is creating and operating water and energy safe quality fruit production systems. To evaluate these possibilities, experience was carried out in the Study and Regional Research Farm of the University of Debrecen near Pallag with the use of a GreenSeeker 505 Hand Held™ Optical Sensor Unit, and its interface the Trimble AgGPS FmX Integrated Display board computer, and a ScanStation C10 laser scanner by Leica. The results show the absolute applicability of these equipments in precision horticulture.

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The impact of environmental factors on the measurement of the normalized difference vegetation index
Published November 13, 2012

The level of nitrogen supply of a plant population can be quickly measured with non-destructive optical measurement devices and the differentiated determination of nitrogen shortage and the replenishment of nitrogen can also be carried out. The level of nitrogen supply is based on the fact that the chlorophyll content of crops is in close corre...lation with nitrogen content and that the amount of chlorophyll can be easily measured on the basis of the light absorption of chlorophyll molecules. The successfulness of optical measurements can be influenced by the change of weather  parameters; therefore, it is important to know the correlations between measurement results and weather parameters when it comes to practical use.
The GreenSeeker Model 505 measurement device determines the relative chlorophyll content in the form of the Normalized Difference
Vegetation Index (NDVI) calculated on the basis of the intensity of the reflected red and infrared rays of light from the crop population. The measurements were performed in alfalfa population with 10 replications at five measurement heights and four measurement times. The weather parameters were measured by a weather station located in the middle of the alfalfa population and the correlations between the meteorological data and the NDVI values were examined. During the statistical evaluation of the results, it was established that the NDVI measurement is primarily influenced by the relative humidity of the air, secondly by air temperature and thirdly by wind speed. Relative humidity was in strong correlation with the NDVI values which were also influenced by the measurement height and time. Regression was not significant in the case of 20 cm  measurement height, but the measurements above 40 cm height showed significant correlations. The correlation was shown to be strong at each measurement time, but the influence of humidity was the lowest at 11:00 and 14:00. 

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Topology in the fruit plantation
Published November 13, 2012

The localization of fruit trees, the topology of the branch structure and the spatial structure of the canopy are important to plan sitespecific agro-ecological and production technology projects in an orchard. The currently used instruments and technologies – in the precision agriculture – give opportunities to obtain these informations. T...he examinations were carried out in the Study and Regional Research Farm of the University of Debrecen near Pallag with the use of a GreenSeeker 505 Hand Held™ Optical Sensor Unit, and its interface the Trimble AgGPS FmX Integrated Display board computer. The collected spectral data were completed with the 3D point cloud by Leica ScanStation C10 laser scanner. The laser impulse data and the vegetation index values were integrated in a unified 3D system. The integration of the two special data collection system provides new opportunities in the development of precision production technology system. The results could be directly used in phytotechnology, water management, plant protection and harvesting in orchards. Our elaborated method can supply digital high spatial accuracy guidance data for development of the automated machines, which could provide some new developmental way in the immediate future.

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Results of the sensory analysis of precision maize production
Published May 23, 2019

This research was carried out in 2018, at the Látókép Experimental Station of the University of Debrecen in a moderately warm and dry production area, on deep humus layered medium-hard calcareous chernozem soil. In the scope of the research, the chlorophyll content of maize (Zea mays L.) was examined under field circumstances by means of sensory measurements and we were looking for correlation between the obtained values and the amount of yield. Our measurements were carried out with Minolta SPAD-502 and GreenSeeker devices at 3 measurement times (4 leaf stage, 10 leaf stage and silking). It was found that phenological phases had an effect on the obtained SPAD and NDVI values and were in a slightly significant correlation with the yield. The most significant correlation was found between the results obtained during silking and the amount of yield. This may be because the least time has passed between the measurement time and harvest. Results obtained during the 10-leaf stage show excessive values in each case, which can be due to a measurement error. It was found that the phenological phase had an effect on the correlation of SPAD and NDVI values and the amount of yield. As the phenological phase progressed, the correlation between the measured results and yield has increased.

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Evaluation of the correlation between SPAD readings and absolute chlorophyll content of maize under different nitrogen supply conditions
Published December 15, 2019

Currently, one of the most important objectives of agriculture is to maintain the principles of the sustainability. The use of precision technologies in agriculture belongs to this topic. The use of precision technologies is increasingly widespread in the cultivation of various agricultural crops, including maize. Sensing is an important part o...f these techniques. In our experiment we compared two methods: measuring relative chlorophyll content and the method of determine the extractable chlorophylls. The experimental plant was maize (Zea mays L.) and the measurements were performed at an early development stage (V8) of three genotypes. Three levels of nitrogen (0; 80; 160 kg ha-1) were applied during the experiment. The relative chlorophyll content was measured by SPAD-502 (Minolta, Japan) and a handheld GreenSeeker (Trimble, USA) device. The extractable total chlorophyll content decreased in parallel with the increased nitrogen level. The obtained SPAD values were diversified furthermore the NDVI values have not been changed for the effect of different nitrogen fertilization. In the early stages of development of maize, these parameters need to be complemented with other measurements to provide reliable information about the crops nitrogen status.

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