The purpose of this study was to investigate the impacts of Spirulina platensis algae extract (seaweed) and Saccharomyces cerevisiae yeast extract as bio-stimulants on the growth, flowering, and chemical composition of the Zinnia elegans plants during 2021 and 2022 seasons. When the seedlings reached about 10 cm in length, they were transplanted into individual pots filled with a mixture of clay and sand (1:1, v/v). Seedlings were sprayed with algae extract at 0.5 and 1% and yeast extract at 3 and 6 g/l however, control plants were sprayed with distilled water. The obtained results indicated that algae extract at 1% treatment increased all vegetative parameters including plant height, stem diameter, number of branches/plant, number of leaves/plant, root length, leaf area, shoot and root fresh and dry weights, flowering parameters including number of inflorescences/plant, inflorescence F.W. and D.W. in both seasons and inflorescence diameter in the second season only. The chemical composition was also positively affected by the same treatment and gave the highest values for photosynthetic pigments, total amino acids, crude protein, macronutrient elements (N, P and K%), total sugar content and total indoles followed by plants sprayed with yeast extract at 6 g/l for all the mentioned parameters during both seasons. It was concluded that algae extract at 1% or yeast extract at 6 g/l can be used as bio-stimulants to boost the growth of the Zinnia elegans plant.
This experiment was conducted in the greenhouse of the National Research Centre during the two seasons of 2019/2020 and 2020/2021 to study the ability of Dimorphotheca ecklonis plants to grow in the soil contaminated with cadmium (Cd) at different concentrations (0, 25, 50 and 100 mg. kg -1 soil), the humic acid was used at concentrations (0, 200 and 400 mg. l -1 ) to improve the plants growth. The plants grown in soil contaminated with Cd at 25mg. kg -1 soil gave the highest mean values of all vegetative growth parameters, photosynthetic pigments and total sugar content; whereas, the plants grown in soil free of cadmium gave the highest mean values for RWC% and all inflorescences parameters in both seasons. The treatment Cd 100 mg. kg -1 increased the leaves content of total phenol, total proline, MDA content and cadmium content in both shoot and root in both seasons. The plants that received humic acid (HA) at concentration 200 mg. l -1 showed significant increase for all vegetative growth parameters, RWC%, all inflorescences parameters, photosynthetic pigments,total sugar content and total phenol content in both seasons, while; proline and MDA content were increased at control HA treatments, Cd content in shoot and root were increased by HA 400mg. l -1 . Regarding the interaction treatments, the plants treated with Cd at 25 mg. kg -1 and HA at 200 mg. l -1 increased all vegetative growth parameters, photosynthetic pigments and total sugar content in both seasons, while the treatment of Cd at 0mg. kg -1 and HA at 200 mg. l -1 significantly increased RWC% and inflorescences parameters, the highest value of total phenol content were produced by treatment Cd at 100 mg. kg -1 and HA at 400 mg. l -1 , proline content and MDA by treatment Cd at 100 mg. kg -1 and HA at 0 mg. l -1 and Cd content in shoot and root by treatment Cd at 100 mg. kg -1 and HA at 400 mg. l -1 . Polyphenol oxidase and peroxidase isoenzymes showed overexpression in treatment Cd at 100 mg. kg -1 and HA at 400 mg. l -1 in the second season.
Drought is a global problem that many countries suffer from, as a result of climate change. Swietenia mahogany tree is grown as an ornamental and timber tree and its wood is used in shipbuilding and furniture manufacturing. Therefore, the goal is to use this type of plant for its multiple uses, while reducing the quantities of water consumed for its growth to cope with the drought conditions by using basil leaves extract as natural extract and eco-friendly, it is noticed that all vegetative growth parameters and photosynthetic pigments decreased by increasing irrigation intervals, the rest chemical constituents were increased by increasing irrigation intervals except total sugar content which showed the highest value at irrigation every 7 days. Treating the seedlings with BLE at 10% enhanced all vegetative growth parameters and photosynthetic pigments and reduce all oxidative markers and so antioxidant compounds, it was concluded that BLE at 10% enhanced the tolerance of S. mahogany seedlings under all irrigation levels. The irrigation every 5 days showed preferable results followed by irrigation every 7 days.
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