Growth and Development of Sweet Basil and Perilla in Response to Different Nutrient Solution Concentrations

Sweet basil (Ocimum basilicum L.) and perilla (Perilla frutescens L.) are popular herbs in United States and eastern Asia, which are also widely used as medicinal plants and functional food materials. To achieve their stable and sustainable production, we investigated the growth and development of sweet basil and perilla in response to different nutrient solution concentrations. Sweet basil (‘Gevenose’) and perilla (‘Asia Ip’ and ‘Shiso Red’) were grown in the greenhouse and irrigated with commercial nutrient solutions (Peters Professional, Everris NA Inc., Dublin, OH) at nitrogen (N) concentrations of 100, 200 and 300 mg L^-1 (N:P:K=20.0:4.4:16.6) for 6 weeks. Plant height and two perpendicular widths were recorded weekly to calculate growth index ((height+(width1+width2)/2)/2). Chlorophyll content, internode number and the electrical conductivity (EC) and pH of the growing substrate leachates were measured (pour-through) weekly, and the photosynthesis of plants were measured at the fourth and sixth week. The results showed that there were no significant differences in growth index, internode number, chlorophyll content and net photosynthesis rate among 100, 200 and 300 mg L^-1 N treatments for both sweet basil and perilla. The leachate EC differed among cultivars and species and treatments. During the six week experiment period, the average leachate EC in the 100, 200 and 300 mg L^-1 N treatments were 0.8 dS m^-1, 1.7 dS m^-1, and 2.6 dS m^-1 in ‘Gevenose’, while they were 0.7 dS m^-1, 1.5 dS m^-1, and 2.4 dS m^-1 in ‘Asia Ip’, and 0.9 dS m^-1, 1.6 dS m^-1, and 2.3 dS m^-1 in ‘Shiso Red’, respectively. Therefore, 100 mg L^-1 N concentration was the most suitable for the growth and development of ‘Gevenose’, ‘Asia Ip’ and ‘Shiso Red’.