Overview of Multiple Applications of Basil Species and Cultivars and the Effects of Production Environmental Parameters on Yields and Secondary Metabolites in Hydroponic Systems

Abstract

Basil (Ocimum basilicum L.), including other species and cultivars, is an excellent source of nutritional compounds, the accumulation of which can be stimulated by exogenous factors (environmental and nutritional conditions). Although best practices are relatively established for mature basil plants, microgreens production requires further research to optimize quality and quantity. The study objectives are (i) to provide an overview of the many uses of basil, (ii) collate and present common hydroponic systems available in the market, (iii) review effects of key production environment parameters on basil yields in hydroponic systems, and (iv) summarize the effects of the growth environments on yield quantity and quality of basil microgreens. The paper analyzes in detail key production parameters of basil microgreens in hydroponic systems, such as temperature, humidity, pH, electrical conductivity, dissolved oxygen, carbon dioxide, nutrient solutions, and the influence of light (quantity, quality, and photoperiods). The collated literature review has shown that basil, grown hydroponically, can tolerate high variations of environmental parameters: pH 5.1–8.5, temperature 15–24 °C, relative humidity 60–70%, electrical conductivity up to 1.2 mS cm−1, depending on the developmental stage, dissolved oxygen at 4 mg L−1 (optimally 6.5 mg L−1), and light intensity between 200 and 400 μmol m−2 s−1. The study has synthesized an overview of different production parameters to provide guidance on the optimization of environmental conditions to ensure the quantity and quality production of basil microgreens. Improving the quality of basil microgreens can ideally spur continued gastronomic interest in microgreens in general, which will encourage more entrepreneurs to grow basil and other microgreens. Hence, the study findings are a great resource to learn about the effects of different environments on basil microgreen production. This information can inform research for successful production of different species and cultivars of basil microgreens, and establishing testing protocols to improve the quantity and quality of the harvest.

Effects of Elevated Water Temperature on Growth of Basil Using Nutrient Film Technique

“…57(8) AUGUST 2022 levels of oxygen in the water can reduce plant growth and development, as well as increase the likelihood of pathogens in hydroponic systems (Yan et al, 2012). However, according to Ruso et al (2021), basil can persist with dissolved oxygen levels as low as 4 mg•L À1 , with optimal levels at 6.5 mg•L À1 . In the present study, dissolved oxygen rates were well above the minimum requirements for basil, thus elevated water temperature provided more benefits than could be accounted for by increased oxygen.…”

Effects of Hydrogen Peroxide Products on Basil, Lettuce, and Algae in an Ebb and Flow Hydroponic System

“…Soffer et al [61] found that chrysanthemums (Chrysanthemum x morifolium L. 'Bright Golden Anne') and the weeping fig (Ficus benjamina L.) both grew faster in oxygensaturated water. According to Ruso et al [62], basil can persist with DO levels as low as 4 mg L −1 , with optimal levels at 6.5 mg L −1 . However, lettuce only needs a DO content of at least 1.6 mg L −1 [63].…”

Trial Protocol for Evaluating Platforms for Growing Microgreens in Hydroponic Conditions

“…Microgreens are emerging functional foods of the 21st century [2] that are gaining interest for their sustained nutraceutical properties and are an optimistic prospect for expanding especially for the consumption of the population in large urban areas and in terms of food security. Production of microgreens using hydroponic systems must be planned and controlled with care for controlling environmental factors in order to increase quality parameters [3][4][5][6]. This is in comparison to more conventional production methods using soil, considering all the controllable factors in hydroponic systems that have been shown to influence the accumulation of bioactive substances [7,8], the harvest timeframe [9][10][11], and the quality of the finished product [12][13][14].…”

“…For instance, there is a wide range of environmental impact factors and variation in their relationships to downstream microgreens outputs, which means that there is no single prescription that will guarantee perfect results [26]. The literature review has demonstrated that there are optimal ranges within which one can begin the task of designing effective prescriptions for successful microgreen production [3,21,27].…”

“…Microgreen producers must integrate specific systematic hydroponic strategies to obtain high-quality microgreens and high quantity [37] and quality bioactive substances [38], while also avoiding the potential for spoilage and low-quality production [20,39] when moving too far beyond the noted parameter ranges [3].…”