Mitigating water deficit stress in lemon balm (Melissa officinalis L.) through integrated soil amendments: A pathway to sustainable agriculture.

Lemon balm (Melissa officinalis L.) is a valuable medicinal plant, but its growth can be significantly impacted by drought stress. This study aimed to mitigate the adverse effects of water deficit stress on lemon balm biomass by integrating poultry manure compost, poultry manure biochar, NPK fertilizer, Trichoderma harzianum, Thiobacillus thioparus, and elemental sulfur as soil amendments. The experiment was conducted in a greenhouse using a completely randomized design with a factorial arrangement, consisting of three replicates. It included a water deficit stress factor at three levels (95-100%, 75-80%, and 55-60% of field capacity) and a soil amendment treatment factor with eleven different fertilizer levels. Treatments included control (no amendment), NPK fertilizer, poultry manure compost, poultry manure biochar, and combinations of these with T. harzianum, T. thioparus, and elemental sulfur under various water deficit levels. Water deficit stress significantly reduced photosynthetic pigments, gas exchange parameters, chlorophyll fluorescence, relative water content, and antioxidant enzyme activity, while increasing membrane permeability and lipid peroxidation in lemon balm plants. However, the integrated application of organic, biological, and chemical amendments mitigated these negative impacts. The combined treatment of poultry manure compost, poultry manure biochar, NPK fertilizer, T. harzianum, T. thioparus, and elemental sulfur was the most effective in improving the morpho-physiological properties (1.97-60%) and biomass (2.31-2.76 times) of lemon balm under water deficit stress. The results demonstrate the potential of this holistic approach to enhance the resilience of lemon balm cultivation in water-scarce environments. The integration of organic, biological, and chemical amendments can contribute to sustainable agricultural practices by improving plant morphological and physiological properties and plant performance under drought conditions.

The effect of bio/organic fertilizers on the phytotoxicity of sulfadiazine to Echium amoenum in a calcareous soil.

The fate of antibiotics and their effects on plant growth may be changed by the application of fertilizers. The present study was carried out to investigate the effect of sulfadiazine (SDZ), rice husk compost (RHC), rice husk biochar (RHB), and mycorrhiza (MR) on the growth attributes of Iranian Echium amoenum Fisch & C.A. Mey. A greenhouse experiment as a completely randomized design with six treatments of bio/organic-fertilizers (no bio-fertilizer (NF), RHB, RHC, MR, RHB+MR, and RHC+MR) and three levels of SDZ application (0, 100, and 200 mg kg-1) was performed for 7months with three replicates. Shoot and root SDZ concentrations were determined using high-pressure liquid chromatography-diode array detection (HPLC-DAD) instrumentation. The results revealed that the application of RHC, RHB, and MR had a significant impact on the reduction of the toxicity effects of SDZ on plant properties. The lowest values of growth parameters belonged to the 200 mg kg-1 of SDZ with no bio-fertilizers, while the highest growth parameters were observed in the treatments of RHB+MR, and RHC+MR with no SDZ application. Also, chlorophyll pigments content was affected by used treatments and the lowest rates of chlorophyll a (4.24), chlorophyll b (2.99), and carotenoids (2.88) were related to the 200 mg kg-1 of SDZ with no biofertilizers application. The co-application of bio-fertilizers and SDZ (at both levels of 100 and 200 mg kg-1) decreased SDZ uptake by both shoot and root in comparison with the control. The same results were obtained with macro (NPK) and micro (Fe, Zn, Cu, and Mn) nutrients uptake by the shoot in which the lowest values of nutrients uptake were observed in treatment of 200 mg kg-1 of SDZ with no bio-fertilizers. Furthermore, in the case of the effect of the used treatments on root colonization, the results showed that the lowest value (7.26%) belonged to the 200 mg kg-1 application of SDZ with no bio-fertilizers. Generally, this study demonstrated that bio-fertilizers could be considered as an effective strategy in controlling the negative effects of antibiotics on the growth properties and nutrients status of the plants grown in such contaminated soils.