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To improve the salt tolerance of Genovese cultivar of sweet basil (Ocimum basilicum L.) plants, an experiment was conducted to evaluate the impact of certain growth substances (salicylic acid, seaweed extract, dry yeast and moringa leaf extract) on growth, volatile oil percentage and yield as well as chemical constituents under saline water irrigation stress conditions (control, 1000, 2000 and 4000 ppm NaCl). The obtained results revealed that the higher salinity levels (2000 and 4000 ppm NaCl) caused significant decreases in vegetative growth measurements of basil plants compared to control and the lowest salinity level (1000 ppm NaCl). Maximum reduction was observed at 4000 ppm NaCl which showed higher increase of the total phenolics and free proline contents. All recoded parameters were enhanced for plants grown under 1000 ppm NaCl. Seaweed extract was superior than other treatments in enhancing the plant tolerance to salinity which appeared in the significantly increasing of growth and volatile oil content of basil. Phenolics and proline contents were increased with salicylic acid treatment comparing with other ones. The best combination recommended as a result of the current study is treating basil plants with seaweed extract under low salinity level (1000 ppm) for improving the growth and volatile oil parameters.

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This study was conducted in the two successive seasons of 2005/2006 and 2006/2007 at the Experimental Farm of Floriculture, Faculty of Agriculture, Assiut University. The aim of this study was to investigate the effect of three rates of each of nitrogen (0, 50 and 100 kg/fed.), active dry yeast (0, 2 and 4 g/l) and tryptophan (0, 50 and 100 ppm) on the growth, fruit and oil yield and chemical composition of fennel plants. The obtained results revealed that the application of nitrogen, active dry yeast and/or tryptophan resulted in a significant increase in vegetative growth, fruit and oil yield as well as fruit content of total carbohydrates, N, P and K compared to the controls. It was interesting to observe that the application of active dry yeast at 4 g/l as biofertilizer with 100 ppm tryptophan as organic nitrogenous source gave nearly equal results to those obtained with the high level of mineral nitrogen fertilizer (100 kg N/fed.) alone. Also, the application of active dry yeast at 4 g/l or tryptophan at 100 ppm combined with 50 kg N/fed. resulted in a significant increase in all studied parameters compared to the high level of nitrogen alone. The maximum vegetative growth and flowering, fruit and oil yield as well as fruit nutrient content were obtained from the combined treatment of 50 kg N/fed. + 2 or 4 g/l active dry yeast + 50 ppm tryptophan.

Potassium (K) levels are decreasing worldwide in agricultural soils, and K deficiency is becoming a major issue. Study on damask rose response to K application is scarce. Furthermore, despite its importance in the cell division, photosynthesis and protein synthesis, there is a lack of published reports on plant responses to zinc (Zn) application. Further research is required to understand the damask rose's response to both elements. This study investigated the effects of K and Zn foliar application on the vegetative growth, flower yield, and volatile oil content and composition of damask rose. K and Zn nutrition was applied either individually or combined as K2SO4 and ZnSO4 at 0.5 or 1.0%. Foliar application of K2SO4 and ZnSO4 was applied with a manual pump four times in each growing season, the first at the beginning of stem elongation and leaf formation, and then at two-weekly intervals. Results showed that K and/or Zn treatments significantly improved the growth characters, flower yield, relative water content (RWC), stomatal conductance, and essential oil content and composition such as linalool, nerol, citronellol, geraniol, and nonadecane. The chlorophyll content, total soluble sugars (TSS), and protein content also increased, but free amino acid content decreased, suggesting that the distribution of nitrogenous compounds (between amino acids and proteins) and their transformation were influenced by K and Zn supply. Individual applications of K or Zn increased the N, P, K, and Zn contents in damask rose leaves, relative to the control, which increased further with combined applications of K and Zn. Results suggest that foliar application of K and/or Zn could be part of the damask rose fertilization program to provide plants with the optimum level of nutrition for improving the quantity and quality of flowers and essential oil yields.