The singular and combined effects of drought and copper stresses on the morphological traits, photosynthetic pigments, essential oils yield and copper concentration of Fumaria parviflora Lam.

High concentrations of copper (Cu) can be extremely toxic for plant growth. Drought stress is also considered as a major environmental tension, as it reduces vegetative growth in medicinal plants. This study evaluated the singular and combined effects of several Cu concentrations (0, 50, 150, 300, and 400 mg kg(-1)) and various drought stresses (non-stress, moderate, and severe) on the different vegetative traits, photosynthetic pigments, essential oils (EOs) yield, and Cu accumulation (in roots, shoots, and distilled plant material) of Fumaria parviflora Lam. under field conditions. The seeds were collected from four zones (Z(1), Z(2), Z(3), and Z(4)) located in two mineral regions (Askari and Rabor) of Kerman, Iran. Drought and Cu, both independently and combined, suppressed plant growth by decreasing different vegetative growth parameters. The Cu concentration of 50 mg kg(-1) yielded the highest values in all morphological traits and photosynthetic pigments. These included the dry weight and length of both shoot and root, chlorophyll content under non-drought stress, and carotenoid content under moderate drought stress. The growth parameters and photosynthetic pigments of F. parviflora declined sharply at Cu concentrations of 300 and 400 mg kg(-1). The highest EOs yield (0.56% v/w) was obtained by applying 150 mg kg(-1) Cu under moderate drought stress conditions in zones Z(3) and Z(4). In the distilled plant material, Cu concentration was almost similar to its concentration in shoots before the distillation process. Under moderate drought and up to a Cu concentration of 150 mg kg(-1), the shoot growth parameters and photosynthetic pigments were slightly less than the control. Moreover, the EOs yield was at its highest, and Cu was mainly accumulated in the roots and only slightly transferred to the shoot. Therefore, to use the shoot and EOs of F. parviflora for medicinal purposes, it is recommended that this plant be cultivated under moderate drought in stressed soils at a maximum copper concentration of 150 mg kg(-1).

Automated summary

This study evaluated the effects of copper concentration and drought stress on Fumaria parviflora and found that moderate drought conditions with a copper concentration of 150 mg kg(-1) resulted in the highest essential oil yield.