# Effect of Magnetic and Electrical Fields on Yield, Shelf Life and Quality of Fruits
## 1 Introduction  
Magnetic and electrical fields occur in the environment and constantly affect living organisms and affect the course of many biological processes [1]. All plants live and develop in the presence of the Earth's magnetic field and the electrical field that occurs between clouds and the Earth [2]. The Earth's magnetic field is mainly produced by the dynamo action of turbulent flows in the fluid metallic outer core of the planet [3]. MF is related to the movement of electrical charges. There are differences on the ground in the strength and direction of the Earth's magnetic (geomagnetic) field. The vertical component of this field is at a maximum at the magnetic pole (about 67 uT) and is zero at the magnetic equator, while the horizontal component is at a maximum at the magnetic equator (about 33 uT) and is zero at the magnetic poles [4]. An electric field is produced by stationary charges [5]. [PERSON] (2012) noted that the combination of an electric field and a magnetic field can be viewed as an electromagnetic field (EMF) [6]. One of the sources producing an electromagnetic field is high-voltage power transmission lines, which may affect the growth of plants and selected crops. A magnetic field (MF) is a source of energy, thereby it has effects on the metabolism of cells [7] and has an impact on meristem cell division [8]. In addition, an MF affects water absorption, preservation, and ionisation [9]. It may cause magnetophoresis in macromolecules [10] and an increase in the chemical reactions of plants, causing a positive effect on photochemical activity, respiration ratio, and enzyme activity [11, 12]. This same stimulation of plants with a magnetic field is a way to increase the quantity and qualityof seed germination, seedling development, and yields of different species, such as field, fodder, and industrial crops, herbs, and medicinal plants [5]. In addition, yield improvement can be achieved with a pre-sowing treatment of seeds with electrical and electromagnetic fields [12; 13; 14]. Research studies have shown that a high-voltage electric field (HVEF) can be used to maintain the freshness of food by extending its shelf life, improving product quality and inhibiting microbial growth [15; 16; 17]. It is classified as a non-thermal and low-energy treatment. The HVEF process is based on the production of an electrical wind by corona discharge between at least two electrodes. Different electrode configurations, such as point-ring, needle-ring, needle-plate, and wire-plate, are commonly used for preparing the electrical field. The ions produced in a small area around the needle electrodes are then accelerated by an electrical field. Corona discharge involves the partial electrical breakdown of the gaseous medium [18; 19]. Research has illustrated that outer electrical and magnetic fields impact on the actuation of ions, polarisation of electric doublet, water absorption, preservation, and ionisation [9; 20]. Many studies have shown that magnetically activated water used in agriculture helps improve germination, plant growth, flowers, fruit, and crop yield. Magnetic treatment of water enhances the overall physical characteristics of the fruit and water productivity [21; 22; 23]. Fruit is essential in human nutrition and health and it contains a very high percentage of water compared with other plant-derived foods, such as seeds. Therefore, they exhibit relatively high metabolic activity after harvest and, in consequence, this leads to the rapid breakdown of the structure of the fruit and the loss of its properties [24]. During fruit ripening, many physiological and biochemical processes take place in their cells. These processes result in changes in the colour, taste, and texture of the fruit [25]. These features determine the acceptance of the fruit by the consumer [26]. During ripening and storage, the fruit softens and loses its hard texture [27]. The rate of change is genetically programmed, but also influenced by environmental factors [28].