Seasonal Changes of Growth and Leaf Perillaldehyde in Perilla frutescens (L.) Britton

Abstract

Perilla frutescens (L.) Britton, a member of Lamiaceae and a native dicot in Asia, is now distributed worldwide including Taiwan. To further explore its uses as a commercial crop, a comprehensive study regarding the growth behavior and chemical components of this plant species is needed. In the present research, changes in growth traits, including plant height, leaf area index and weights of aerial parts, and leaf perillaldehyde (PA) concentration and content were investigated for plants grown in different growing seasons in the experimental period from 2004 to 2006. The five-leaf stage seedlings were transplanted in March (Season I), April (Season II), May (Season III) June (Season IV) and July (Season V), respectively. Concentration of leaf PA was determined by High Performance Liquid Chromatography (HPLC). Results showed that plant height was taller and leaf area index and fresh weights of aerial parts were larger for plants grown in cooler Season I relative to those plants grown in other warmer seasons (Seasons II-V), implying that warming conditions during growing periods was not in favor to plant growth. Seeds harvested at maturity were found varied in different growing seasons and seed produced in Season V was the lowest. In contrast, the highest value of 500-seed weight also obtained from seeds produced in Seasons V. The PA concentration in the primary leaves on the main stem from position 10 to 15 was higher than others and the quadratic pattern was similar in different growing seasons in 2004–2006. The distribution pattern of leaf PA content was in accordance with leaf PA concentration during the growing periods. In considering the proportions of PA distributed in leaves emerged on the main stem and the lateral branches, the proper time period to harvest the highest quantity of leaf PA for a single plant was from 110 to 120 days after transplanting.