This research study was carried out in the open field during the two successive seasons of 2012/2013 and 2013/2014. The aim of this investigation was to study the response of pot marigold (Calendula officinalis L.) to different application methods and concentrations of seaweed extracts applied as a commercial compound. Seven treatments were initiated, i.e. three concentrations of seaweed extracts (500, 1000, 1500) were used either as foliar spray or as soil drench in addition to the control treatment (tap water). Results indicated that foliar spray with 1500 ppm of seaweed extract increased significantly plant height, number of flowers per plant and vase life in the two tested seasons. However, foliar spray with the lowest concentration of seaweed extract (500 ppm) resulted in significant increments in flower stalk length, flower diameter and carbohydrates content. Moreover, the same concentration showed significant increases in total carotenoids, nitrogen, and phosphorus percentage when used as soil drench in the two tested seasons.

This study was carried out to investigate the effect of saline water irrigation at 2000, 4000, 6000, 8000 and 10000 ppm by using a mixture of two salts (sodium chloride: calcium chloride, 2:1, w/w)  in addition to tap water  as control and foliar sprayings of Salicylic acid (SA) at 100, 200 and 300 ppm in addition to tap water as control on growth, flowering and chemical composition of pot marigold plants in the two successive seasons of 2014/2015 and 2015/2016 in the Faculty of Agriculture, Ain Shams University, Qalyubia Governorate, Egypt. Results revealed that all tested foliar applications of SA increased all vegetative growth characteristics (plant height, number of leaves /plant, leaf area, number of branches/plant, diameter of stem, fresh and dry weights of vegetative growth and roots, and roots volume), and flowering attributes (number of inflorescences/plant, diameter of inflorescence, fresh and dry weights of inflorescences). While, saline water irrigation decreased growth, flowering parameters, chlorophyll, carotene contents in flowers and some minerals contents of the vegetative growth, i.e. nitrogen, phosphorus and potassium percentages. However, saline water irrigation increased proline and some mineral contents, i.e. calcium, sodium and chloride percentages of the vegetative growth. In most cases, under the same saline water irrigation conditions spraying SA at 100 and 200 ppm concentrations alleviated the salinity effect on the plants, enhanced the plant growth and increased the flowering parameters. The most effective treatments which enhance growth, flowering parameters, chlorophyll content, carotene contents in flowers, proline and mineral contents were found to be 100 and 200 ppm SA spraying under nonsaline conditions.