###### Abstract
Second, for a given plant, realizing a custom LED light source accordingly with the optimal light combination of the plant, avoids power waste related to light wavelengths that have no effects on the growth of the plant. These considerations are valid not only for a monochromatic LED, but also for white LEDs. It is well known that white LEDs do not produce directly white light. There are two main manufacturing process to realize white LEDs. The first one is a conventional process that exploits RGB-LEDs dies on the same chip. In this case, it is possible to change the color temperature of the produced white light by acting on the current flowing into the LED that in turn vary the light intensities of the single RGB-LEDs. The second one is called fluorescence (GaN-LED) and exploits a blue LED (or UV in some cases) only with a special yellow coating realized with phosphor. In this case, a phosphor coating is deposited on the blue LED die. The color temperature of the obtained white light depends on the dominant wavelength of the blue LED used [15]. According to the more recent research, plants' chlorophyll molecules absorb the red and blue spectral components most efficiently, and for this reason, red and blue spectral components best drive photosynthetic metabolism and are the most relevant for crop growth [16]. In addition, exposure to red and blue light increases the content of phenolic compounds and improve antioxidant activity in various leafy greens with respect to only white light exposure, including if these effects are different among the species [16, 17, 18]. Blue light, having short wavelength, has the capability to regulate plant growth at different stage, promoting, when in considerable presence, compactness, and plant density [19, 20, 21, 22]. Red light, having longer wavelength, has beneficial effect on stem elongation and leaf area [23,24]. However, green and yellow light components are less compatible to plant receptor, and they are principally reflected or transmitted and thus are not as important in the photosynthetic process. For basil cultivation the main works are focused on phenolic biosynthesis and accumulation but few of them are related to systematic cause-effect investigation on growth and yield performance under artificial lamps [1,7]. In addition, up until now, few studies investigate this effect in a systematic way and comparison among different studies is not trivial due to the different boundary condition employed for basil cultivation. In particular, hyper red (660 nm) light component effect on plant growth is not fully understood yet, as it seems to contribute to increase the plant' yield and quality, but, at the same time, promoting a reverse effect of phytochromes leading to changes in plant morphology, gene expression, and reproductive responses [25; 26; 27]. On these bases, the main objective of the present study is to evaluate the artificial illumination spectrum that is capable to induce the most significant biomass improvement of \"Genovese\" basil (_Ocimum Basilicum_) plants in a controlled environment. Following the results presented in [28] three different light-plants distances and four different LEDs modules have been considered in combination. From a previous study, the effect of different artificial lights was evaluated as negligible, with respect to a fertilizer addition, to promote basil growth [28]. A slight favorable effect was estimated for a combination of LEDs light containing hyper red and deep blue light in a proportion of 1:3 (LEDs modules quantity), but further investigation was necessary [28]. A statistical approach (design of experiments) has been applied to reduce the number of possible combinations of the variables, and, consequently, of the experiments needed to obtain statistically reliable correlation among data [29]. Data inherent to germination, growth and plant's water consumption have been collected to demonstrate and calculate, numerically, specific effects of artificial light conditions on basil cultivation.