Fruit annual changes in morphological characteristic and essential oil accumulation of Litsea cubeba

Abstract

Abstract Litsea cubeba (Lour.) Pers. is an important spice plant in southern China. The whole plant of Litsea cubeba contains essential oils, among which the fruit has the highest essential oil content. And there is a significant market demand and widespread use of essential oil of Litsea cubeba fruit. However, there are few systematic studies on the growth and development of the Litsea cubeba fruit. This study aims to determine the regularity of annual changes in fruit morphology, essential oil content, and components of Litsea cubeba essential oil to determine the optimal harvest period and improve the utilization efficiency of Litsea cubeba resource. The results show that the annual change of fruit morphology of Litsea cubeba was consistent with the double "S" curve, which shows a general trend of rapid growth first, then slow growth, and finally rapid growth again. While the annual change of the essential oil of Litsea cubeba fruits was consistent with a single "S" curve, which shows a general trend of slow growth first, then rapid growth, and finally decreasing rapidly. Correlation analysis showed a significant negative correlation between morphological changes and essential oil accumulation in Litsea cubeba fruit. Combining the growing periods of fruit morphology and essential oil accumulation, the growth and development of Litsea cubeba fruit can be divided into four general periods: the first rapid growth period (rapid growth in fruit diameter and fruit weight with slow accumulation of essential oil), the essential oil accumulation period (rapid accumulation of essential oil with slow growth in fruit diameter and fruit weight), the second rapid growth period (fruit diameter and fruit weight increased rapidly for the second time while the essential oil content started to decrease), and the shriveling period (fruit diameter and weight and essential oil content all decreased rapidly). This study further confirmed that citral was the highest component in the essential oil of Litsea cubeba. When citral extraction is needed, the fruit can be harvested 139–149 days after anthesis.