الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
5.1. Summary of Results
• All examined fertilization treatments had a positive effect on growth of the two cultivars (Yellow and Orange) of Calendula officinalis when compared to the no-fertilized control which is quite obvious.
• Mineral N, P and K fertilization proved to be more effective than compost in influencing growth of the two cultivars of Calendula officinalis,
regardless of compost levels tried (25%,50%,75% or 100%).This was forecasted too since mineral fertilization, presumably in most cases, makes nutrient elements available and absorbed by plants in a readily manner.
• The yellow cultivar of Calendula officinalis was superior than the orange cultivar in all growth parameters studied, i.e. plant height, above-ground fresh and dry weights, number of flowers/plant and in both flower diameter and dry weight. Whereas, the orange cultivar was exclusive than the yellow cultivar in some internal chemical constituents analyzed, i.e., P total carbohydrates, and in both polyphenols and flavonoids contents.
• When mineral fertilization level was reduced to 75 % and replaced with 25 % compost, the obtained results could be summed up as follows:
– All growth parameters studied, i.e. plant height, above-ground fresh and dry weights was less by 8.4 %, 6.3 %, and 8.5% when compared to 100% mineral in both cultivars for the1st and 2nd season.
– Flowering parameters studied, i.e. number of flowers/plant, flower diameter and flower dry weight/plant were less by 12.6 %, 7 %, and 14.3 % when compared to 100%mineral in both cultivars for the1st and 2nd season.
– All internal chemical constituents analyzed, i.e. N, P and K Chlorophyll a and b, Carotenoids, total carbohydrates,
in both total polyphenols and flavonoids contents, in addition to yield of essential oil (as a percentage) were less by 9.8 %, 10.3 %, 8.4 %, 8.5 %, 13.5 %, 4.9 %, 3.3 %, 9 %, 8.3 %, and 2 % low when compared to100% mineral in both cultivars for the1st and 2nd season.
– Yield of essential oil (as a percentage) and oil main constituents determined, i.e. (α-Cadinol, δ- Cadinene, β-eudesmol and γ- Cadinene) were increased by 3.4 % , 2 % , 4 %, 3 % , 3.5 % in the orange cultivar of Calendula officinalis when compared to the yellow cultivar and when coupled with the full dose (100%) mineral fertilization.
5.2. Conclusions
• If it is possible to replace mineral fertilization by an organic substitute this would definitely reduce detrimental effects on the environment not to mention health risks. Some chemical fertilizers contain traces of heavy metals, e.g. lead and mercury and cadmium which are extremely hazardous. In addition, excessive use of nitrogen could lead to methemoglobinemia.
• To reach a final decisive recommendation a feasibility study must have been carried out to say if the cost of replacing mineral fertilization partially with compost would be justified moneywise, especially on essential oil yield and active components when lowered a little bit. Unfortunately, as it was not carried out in this research study, so the final conclusion would be left at the point that there is a possibility of replacing mineral fertilization by 25% compost to not only benefit both the environment and health status but also justify economical loss of not applying 100% mineral fertilization.