New evaluation method to detect physiological stress in fruit trees by airborne hyperspectral image spectroscopy

Nowadays airborne remote sensing data are increasingly used in precision agriculture. The fast space-time dependent localization of stresses in orchards, which allows for a more efficient application of horticultural technologies, could lead to improved sustainable precise management. The disadvantage of the near field multi and hyper spectroscopy is the spot sample taking, which can apply independently only for experimental survey in plantations. The traditional satellite images is optionally suitable for precision investigation because of the low spectral and ground resolution on field condition. The presented airborne hyperspectral image spectroscopy reduces above mentioned disadvantages and at the same time provides newer analyzing possibility to the user. In this paper we demonstrate the conditions of data base collection and some informative examination possibility. The estimating of the board band vegetation indices calculated from reflectance is well known in practice of the biomass stress examinations. In this method the N-dimension spectral data cube enables to calculate numerous special narrow band indexes and to evaluate maps. This paper aims at investigating the applied hyperspectral analysis for fruit tree stress detection. In our study, hyperspectral data were collected by an AISADUAL hyperspectral image spectroscopy system, with high (0,5-1,5 m) ground resolution. The research focused on determining of leaves condition in different fruit plantations in the peach orchard near Siófok. Moreover the spectral reflectance analyses could provide more information about plant condition due to changes in the absorption of incident light in the visible and near infrared range of the spectrum.

Promising white poplar (Populus alba L.) clones in sandy ridges between the rivers Danube and Tisza in Hungary

White poplar is a native stand-forming tree species in Hungary, covering 3.1 per cent of the forested area. More than 70 per cent of the white poplar stands can be found on calcareous sandy sites in the Danube—Tisza region, so they play a significant role in the poplar management of this part of the country. The most important task ahead of Hungarian poplar growers is to improve the quality of poplar stands and plantations based on selecting new clones and cultivars. The growth and yield of four promising white poplar clones was evaluated on a marginal site in central Hungary. The clones `1-1 425-4' (Populus alba x Populus alba), and 11 758' (Populus alba Mosonmagyaróvár 124) seem to be suitable for wood production, while the 427-3' (Populus alba x Populus alba cv. Bolleana) and 422-9' (Populus alba x Populus grandidentata) clones (with decorative stem form) could be better used for tree lines and ornamental plantations.

The effect of spring frosts on the nectar production and the bee visitation of fruit trees

Fruit tree species suffered very strong spring frosts in 1997 in Hungary. This caused partial or total damages at buds and flowers depending on site and time of blooming. It was demonstrated at a number of experiments that frost and cold weather also strongly affected the nectar production of surviving flowers. No or very little amount of nectar was measured in flowers first of all of early blooming fruit tree species (apricot) but also of pear and apple in some places. In spite of this fact intensive honeybee visitation was detected in the flowers of fruit trees that suffered partial frost damage only at those sites where honeybee colonies were placed in or at the experimental plantations and the lack of sufficient amount of nectar did not affected bee behaviour seriously on fruit flowers. This means that bad nectar production failed to affect bee visitation of fruit trees definitely. The reason for this was the fact that not only fruit trees but another early bee plants (wild plants, too) suffered frost damage. Accordingly, in lack of forage bees intensively searched for food at blooming fruit trees with some living flowers. Consequently, there was an acceptable yield at those plantations where bud and flower damage was not complete. Accordingly, intensive bee visitation (that is moving additional bee colonies to overpopulate fruit orchards with honeybees) can be an effective tool to decrease or eliminate the detrimental effect of spring frost on the yield of fruit trees where bud or fruit damage is not too high.


The tests of effectiveness of Frostbuster under excessive weather conditions in an apricot plantation

Frostbuster is a new system, engine and technology, developed to protect fruit plantations from the frost damage. In order to raise domestic experiences and measurements, experimental approach has been initiated to prove the utility of the system under excessively low temperature in the plantation of the Siófoki Gyümölcstermesztési Zrt (Fruit Growing Co. Siófok). The first opportunity ensued in the night of February 23-24, 2011, when the temperature sank to 12°C below zero. The question was to see whether we could prevent the drop of temperature by the frostbuster technique. The margin of an anticyclone staying on East Europe secured a stable condition to make tests. The only difference from the imaginable conditions of dangerous frosts was the heat keeping capacity of trees was weak, much inferior than compared with trees in full boom. As a consequence, the tree rows represented much lower heat-capacity and cooled down much quicker than blooming trees in springtime, i.e. their temperature was more variable. The other difference was, compared with an episode in spring that the hard frost lasted much longer than usually in spring. For testing the system, those conditions had even more advantage. Six meteorological stations helped us in measurement. Data-collectors were timed to 1 minute distances and the bulk of data proved to be beneficial for testing the Frostbuster. The results prove that the system is adequate to keep the temperature continuously higher than the surrounding field under excessively low temperatures. Further measurements are still needed to find the optimal solutions fitting to the growing site and its microclimate. Results presented offer a basis of further proofs.