ABSTRACT
Drought stress is known to diminish the growth and yield of plants by altering the physiological, biochemical and molecular processes, thus threatening food security worldwide. Nanoparticles (NPs) have emerged as an effective strategy to raise plant productivity under current rapid environmental challenges. However, there is little literature on mechanisms underlying the beneficial role of re-watering in drought-stressed plants treated with NPs. In this study, the effects of cerium dioxide nanoparticles [(CeO2 NPs), 0 (control), 125, 250, 500, and 1000 mL L-1] were investigated on morpho-physiological and phytochemical traits of Salvia mirzayanii plants under different drought stress intensities [(25%, 50%, 75%, and 100% (control) of field capacity (FC) moisture] and post-stress re-watering (recovery) in a three-way factorial arrangement based on randomized complete block design. Uptake and accumulation of CeO2 NPs in the leaf tissue of plant samples were confirmed using SEM and EDX techniques. The results of ANOVA demonstrated that growth and physio-phytochemical traits were significantly (p < 0.05) affected by individual treatment and/or their double and triple interactions. Exposure to various levels of CeO2 NPs during drought stress mitigated the adverse effects of stress on growth parameters (e.g., plant height, shoot and root dry weights, and root length) and photosynthetic pigments (chlorophyll a and b) content compared to the respective controls in varying degrees. However, proline and essential oil content were increased in drought-stressed plants, and tended to decrease during the period of recovery. Before re-watering, the antioxidant enzymes, CAT, POD, and SOD, activity in leaf tissues was increased with the increase of drought stress intensity upon both treated and non-treated CeO2 NPs conditions. However, the three-way interaction results demonstrated that recovery after drought stress following CeO2 NPs application particularly 1000 mL L-1 decreased the activity of antioxidant enzymes compared to the controls. Based on GC and GC-MS analysis, all essential oil samples predominantly composed of oxygenated monoterpenes and sesquiterpenes including Decane, Spathulenol, Octane, α-Terpinyl acetate, Hexyl isovalerate, Dodecane, Butanoic acid, Linalool, δ-Cadinene, Muurolol, α-Cadinol, Eudesm-7(11)-en-4-ol, which significantly (p < 0.05) changed under different experimental treatments. The recovery after stress, however, increased only the content of δ-Cadinene in plants from severe drought stress upon foliar application of 1000 mL L-1 CeO2 NPs compared to the non-recovery period. Conclusively, integrative use of CeO2 NPs and re-watering after drought stress could be an encouraging and eco-friendly strategy to improve both drought tolerance, growth and pyhtochemical contents in S. mirzayanii plants.
ABSTRACT
To investigate the effect of different levels of bioplex manganese along with probiotics and multi-enzymes on the performance and immune system of broilers, 640 one-day-old male chicks of the Ross 308 strain were reared and the data analysed in a 4 × 2 × 2 factorial experiment with four levels of bioplex manganese (0, 60, 72 and 84 mg per kg of diet), two levels of Parsilact probiotic (0 and 200 mg per kg of diet) and two levels of Combo multi-enzyme (0 and 1,000 mg per kg of diet) in a completely randomized design with 16 experimental treatments, 4 replicates and 10 chickens per replicate during a period of 42 days. The results showed that the performance of the broiler chickens in the diets containing 72 and 84 mg bioplex manganese along with probiotics and multi-enzymes had the greatest difference compared to the control (p < .05). Compared to the control with 0 mg/kg manganese; the bursa of Fabricius weight was greater in chickens fed diets containing additional manganese (p < .05). The concentration of antibodies produced against Newcastle disease virus, as well as the concentrations of IgG, IgM and total immunoglobulins produced against SRBC, were highest in the group fed a diet containing 84 mg manganese along with probiotics and multi-enzymes (p < .05). The results show combining additional manganese with probiotics and multi-enzymes in chicken diets leads to better performance as well as a stronger immune system of chickens.