Quantitative and qualitative response of Dragon's head ( Lallemantia iberica Benth) to different fertilizer sources and water deficit conditions

Dragon's head plant is a vital source of antioxidants, antibacterials and pain relief. This research studied the effect of different fertilizer sources on some characteristics of Dragon's head at different water-deficit levels. The experimental design was a split plot based on a randomized complete block design with three replications. Experimental treatments included irrigation regimes at 3 levels (normal, mild and severe water deficit) and different fertilizer sources (control, NPK, humic acid, vermicompost and manure) conducted in 2 crop years. The results showed that severe water stress reduced the content of chlorophyll a (25.0 %), chlorophyll b (29.24 %), carotenoids (24.32 %), number of seeds per plant (60.08 %), biological yield (24.61 %), nitrogen (18.29 %) and potassium content (38.83 %) compared to the normal condition. In contrast, proline (18.81 %), carbohydrate (18.64 %), phenol (22.16 %), flavonoid (13.4 %), DPPH (24.63 %) and nitric acid radical scavenging (32.27 %) increased with severe water stress compared with the normal condition. Application of vermicompost increased the content of chlorophyll a (92.45 %), chlorophyll b (86.76 %), carotenoids (85.311 %), number of seeds per plant (87.81 %), biological yield (93.23 %), essential oil present (14.29 %), phenol (50.32 %), flavonoid (29.07 %), DPPH (15.83 %), nitric acid radical scavenging (42.47 %), chain-breaking capacity (6.18 %), nitrogen (19.49 %) and potassium content (26.62 %) over the control. The highest thousand kernel weight (32.5 g), seed yield (2343.6 kg ha-1 ), essential oil yield (2.76 kg ha-1 ), mucilage % (15.37 %) and mucilage yield (337.8 kg ha-1 ) were recorded in the vermicompost under normal irrigation conditions. Additionally, vermicompost and animal manure treatment under mild stress conditions increased seed yield, essential oil yield, mucilage % and mucilage yield significantly compared to the corresponding control.