Hydroponic Basil Production: Temperature Influences Volatile Organic Compound Profile, but Not Overall Consumer Preference

Altering the growing temperature during controlled-environment production not only influences crop growth and development, but can also influence volatile organic compound (VOC) production and, subsequently, sensory attributes of culinary herbs. Therefore, the objectives of this study were to (1) quantify the influence of mean daily temperature (MDT) and daily light integral (DLI) on key basil phenylpropanoid and terpenoid concentrations, (2) determine if differences in sensory characteristics due to MDT and DLI influence consumer preference, and (3) identify the sweet basil attributes consumers prefer. Thus, 2-week-old sweet basil ‘Nufar’ seedlings were transplanted into deep-flow hydroponic systems in greenhouses with target MDTs of 23, 26, 29, 32, or 35 °C and DLIs of 7, 9, or 12 mol·m−2·d−1. After three weeks, the two most recently mature leaves were harvested for gas chromatography–mass spectrometry (GC–MS) and consumer sensory analysis. Panel evaluations were conducted through a sliding door with samples served individually while panelists answered Likert scale and open-ended quality attribute and sensory questions. The DLI did not influence VOC concentrations. Increasing MDT from 23 to 36 °C during production increased 1,8 cineole, eugenol, and methyl chavicol concentrations linearly and did not affect linalool concentration. The increases in phenylpropanoid (eugenol and methyl chavicol) were greater than increases in terpenoid (1,8 cineole) concentrations. However, these increases did not impact overall consumer or flavor preference. The MDT during basil production influenced appearance, texture, and color preference of panelists. Taken together, MDT during production influenced both VOC concentrations and textural and visual attribute preference of basil but did not influence overall consumer preference. Therefore, changing the MDT during production can be used to alter plant growth and development without significantly affecting consumer preference.

Response of Basil (Ocimum basilicum) Growth and Yield to Planting Densities and Row Arrangements in Tomato-Basil Intercropping System

Wondo Genet area, which is located in the Sidama zone of south Ethiopia, is characterized by a rapidly increasing human population and scarcity of arable land per household. There is a need for developing an efficient cropping system to use the limited land efficiently and to enhance food security. An experiment was, therefore, was conducted at Wondo Genet Agricultural Research Center under irrigated during the 2018 cropping season to examine the growth and yield of sweet basil under different planting densities and row arrangements in tomato-sweet basil Intercropping System. The experiment was conducted with two basil row arrangements (one tomato row alternating with one basil row (1T:1B) or with two basil rows (1T:2B)) and four basil population densities (66666, 50000, 33333 and 16666 plants.ha^-1) factorial arrangement in RCBD with three replications each consisting of ten treatments. Results of the study indicated that the row arrangement by planting density interaction significantly influenced the yield of basil with the maximum dry herbal (341.49 kg.ha^-1) and essential oil (22.86 kg.ha^-1) yields were recorded at 100% basil population density with a 1T:2B row arrangements. The cropping system significantly influenced the essential oil content and essential oil yield of basil. The highest essential oil content (1.26%) and essential oil yield (21.83 kg.ha^-1) of basil were obtained at sole planting compared to that of intercropping (0.96%) and (15.36 kg.ha^-1) with tomato showing 23.81% and 29.64% reduction, respectively. Therefore, intercropping 100% basil population in tomato by 1T:2B row arrangements could be recommended for Wondo genet and similar agroecology area, based on its better compatibility and productivity.

Response of Sweet Basil (Ocimum Basilicum L.) to Spray of Aspartic and Glutamic Acids, and Their Effect on Its Growth and Its Volatile Oil Content

Experiment was conducted in fields of Agriculture College, Al-Muthanna University, during the growing season 2020, to study the response of sweet basil (Ocimum basilicum L.) to spraying three concentrations of aspartic acid (0, 75 and 150 mg.L−1) and with three concentrations of glutamic acid (0, 75 and 150 mg.L−1), and their impact on its growth and essential oil content. Results showed that the basil plants that have been sprayed with aspartic acid at a concentration (150 mg.L−1) significantly superior in plant height, fresh and dry weight of shoot, percentage and yield of volatile oil (45.61cm, 19.70 gm.plant−1, 1.80 gm.plant−1, 1.75 % and 31.48 μL.plant−1) respectively. Results also showed the significant effect of spraying glutamic acid at a concentration (150 mg.L−1), which gave highest values in plant height, fresh and dry weight of shoot, percentage and yield of volatile oil (48.67 cm., 20.28 gm.plant−1, 1.83 gm.plant−1, 1.56 % and 29.08 μL.plant−1) respectively.