Zoran S. Ilić, Lidija Milenković, Ljubomir Šunić and Maja Manojlović
The photoselective, light-dispersive shade nets can be used as an alternative to protect crops from adverse environmental conditions such as; excessive solar radiation, heat and drought stress, wind and hail, birds, flying pests, thus improving crop’s production, yield and quality. The physiological parameters discussed in the review include: vegetable growth parameters (leaf area, leaf chlorophyll), tissue structure, fruit ripening, physiological disorders, pest and disease incidence, fruit quality parameters (soluble solids content and titratable acidity), bioactive compounds (antioxidant activity, ascorbic acid, carotenoid and flavonoid contents) and aroma volatile compounds at harvest. Also, it is evident in the reviewed literature that light quality influences the biosynthesis, accumulation and retention of vegetable phytochemicals, as well as the decay development during storage. These new strategies to modulate light quality should be conveyed to vegetable producing farmers, thus allowing them to preserve the freshness and post-harvest quality of vegetables for an extended period of time, and to meet the consumers demand for vegetables with high nutritional value all year round. Research on light manipulation in horticultural systems is necessary for a sustainable and market-oriented open field and greenhouse vegetable production in the future.
Zoran S. Ilić, Elazar Fallik, Maja Manojlović, Žarko Kevrešan and Jasna Mastilović
Quality of produce cannot be improved after harvest, only maintained. Postharvest handling depends on the specific conditions of production, season, method of handling, and distance to market. Under organic production, growers harvest and market their produce at or near the peak ripeness more commonly than in many conventional systems. Organic production often includes more specialty varieties whose shelf life and shipping traits are reduced or even inherently poor. Harvesting and handling techniques that minimize injury to the commodity, as well as increased care with field and packinghouse sanitation, (chlorine, ozone, calcium hypochlorite, sodium hypochlorite and chlorine dioxide, acetic acid, peroxyacetic acid, vinegar, ethyl alcohol, hydrogen peroxide, etc.) during postharvest processes are vital components of a postharvest management plan for organic products. Sodium carbonate, sodium bicarbonate, and physical treatments such as heat treatments (as hot water treatment or dips, short hot water rinsing and brushing or hot air) can significantly lower the disease pressure on the harvested commodities. These sanitation practices are very easy to implement in the organic food production chain. They start in the field and continue during harvesting, sorting, packing, and transportation and continue even in the consumer’s home. All those treatments reduce rot development, provide quarantine security, and preserve fruit quality during cold storage and shelf life. In addition, the use chitosan, propolis, methyl jasmonate, essential oils, carnuba wax, biocontrol agents and modified atmosphere packaging can also reduce decay development during prolonged storage. All these treatments can be applied alone or in combination with each other in order to improve decay control after harvest and provide a healthy and safe product to the consumer. The aim of this chapter is to shed more light on the latest information on permitted treatments for organic products and on the possible mode-of-action of these treatments. This chapter summarizes technologies developed over the past five years that explore special physical treatments applied either directly, or in combination with other means to control rot development and insect infestation on fresh produce.
D.Smiljana Paraš, B. Radoslav Gajanin, Lj. Maja Manojlović and Nj. Zoran Ružić
The emission of high frequency electromagnetic fields (HF EMF) produced by antennas for mobile communications has been controversially alleged to have adverse health effects. The aim of our work was to examine whether there are effects on living organisms from HF EMF produced by mobile communication antennas. In this experiment Wistar strain rats were exposed to HF EMF with the following characteristics: 1.9 GHz frequency, 0.24 A/m intensity, electric field strength of 4.79 V/m, and SAR (specific absorption rate) value of 2.0 W/m2. Exposure time was 7 hours per day, 5 days per week, over the course of sixty days. This experiment was conducted on a total of 30 male rats divided randomly into two equal groups: one group of animals was exposed to GSM fields (Global System of antennas for Mobile Communications) as described above whereas the other group of animals was not exposed to any GSM fields. In our study, results show that the quantity, diameter and numerical density of the islets of Langerhans in the pancreatic tissue increased in rats exposed to HF EMF compared to the unexposed group. The volume density, number and numerical density of pancreatic cells also changed in rats that were exposed to the HF EMF compared to the unexposed group. Our study shows a change in the stereological and histological parameters of rat pancreatic tissue due to the effects of HF EM fields produced by antennas for mobile communication.
Dragana Stamenov, Simonida Đurić, Timea Hajnal Jafari, Vladimir Ćirić and Maja Manojlović
The purpose of this study is to investigate the microbial activity and the number of different groups of microorganisms in the soil under organic agricultural systems.
A range of analyses was conducted on soil samples taken from calcareous chernozem soils managed under organic (7 sites) and conventional agricultural systems (1 site). Laboratory measurements were performed in the Laboratory of Microbiology, Faculty of Agriculture, Novi Sad. The total number of bacteria, actinomycetes, fungi, aminoheterotrophs and azotobacters was determined using the dilution method. Soil dehydrogenase activity was measured spectrophotometrically.
The greatest number of the Azotobacter sp. bacteria was recorded in the soil devoted to pumpkins (132.61 × 102) and in the soil devoted to apples (126.39 × 102). The greatest number of aminoheterotrophs (1786.05 × 106) and the total number of bacteria (1370.82 × 106) and actinomycetes (235.45 × 104) were determined in the soil devoted to carrots. Fungi were more abounded in the soil devoted to chard (36.82 × 104) than in the soil devoted to other plants. The research results show that the soil devoted to wheat in organic production indicated a greater number of aminoheterotrophs, total bacteria, actinomycetes and fungi, whereas only the number of Azotobacter sp. was greater in the soil devoted to wheat in the conventional agricultural system. The highest dehydrogenase activity level was determined in the soil devoted to radishes, whereas the lowest dehydrogenase activity level was determined in the soil devoted to apples.