Biostimulants Enhance Bioactive Constituents of Chamomile in Different Intercropping Systems with Garlic. A Case Study

Abstract

Chamomile essential oil (EO) and garlic are extensively used in cosmetics, food, and pharmaceutical industries owing to some important active substances that they contain. The effects of different concentrations of Aminol Forte (AmFo) as a plant biostimulant (PB) were assessed on the yield and bioactive constituents of chamomile, when intercropped with garlic, in a field-based trial at Darab Agricultural Research Station (DARS), Fars province, Iran. The trial was set up as a factorial experiment based on a randomized complete block design (RCBD) with three replications. The first factor was the cropping system (CS) at seven levels, and the second factor was the foliar application of AmFo at three concentrations, including 0% (as control), 0.25%, and 0.5%. During two years of the research (2017/2018 and 2018/2019), changes in fresh weight (FW), dry weight (DW), and bioactive constituents were monitored. Compared with the chamomile monocropping (CS1), the intercropping treatments significantly (p < 0.05) decreased the chamomile flower yields. However, there were no significant differences between the CS1 and CS3 treatments in FW and DW. Unlike FW and DW, the CS treatments had no effect on the bioactive constituents, and no significant difference (p < 0.05) was found among CS treatments. It was found that the biostimulant treatments had no significant effects on the chamomile flower yields, but they elevated the average level of bioactive constituents. These treatments significantly increased the level of chamazulene, α-bisabolol, α-phellandrene, β-bisabolene, and farnesene by 24.47, 11.99, 18.50, 13.41, and 29.32%, respectively. On the other hand, the average levels of α-bisabolol oxide-A, α-bisabolol oxide-B, and linalool were significantly decreased by 19.66, 41.41, and 4.26%, respectively. In general, co-application of AmFo and intercropping can be recommended as an alternative to reduce the demand for chemical fertilizers and improve EO quality.