الفهرس 
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Abstract
The present study was carried out during two successive seasons 2006 and 2007 to explore the response of roselle, Hibiscus sabdariffa var. Sabahia 17 plants to EM (effective micro- organisms), Minia Azotein and ascorbic acid in comparison with the recommended NPK fertilization, in terms of vegetative growth , fruit and yield of sepals and seeds, as well as, photosynthetic pigments, anthocyanin %, acidity % and herb nitrogen %. Each of EM, Minia Azotien and ascorbic acid was used at either high or low concentration. Also, such three materials were applied by three methods, seed soaking (SK), seedling spray (LA) or both SK + LA.
The most important results could be summarized as follows:
Vegetative growth characters:
• The five studied vegetative growth characters of roselle plants, namely plant height, stem diameter, number of branches / plant and herb fresh and dry weight/ plant were considerably increased due to the use of NPK fertilization treatment over other EM (effective micro- organisms), Minia Azotein and ascorbic acid treatments. In the second place were EM and Minia Azotein which were almost equal in giving intermediate values for such vegetative traits, regardless of the used concentration or method of application. Ranked third was ascorbic acid which resulted in the least values.
• Concerning the two used concentrations, within each of EM, Minia Azotein and ascorbic acid, the high one proved to be much more effective than the low one in producing taller plants, thicker stems, more branch number and heavier herb fresh and dry weights. In regard to the three tested application method treatments, the dual one which including seed soaking plus seedling spray surpassed either seed soaking or seedling spray solely. It was interesting to find out that the use of EM or Minia Azotein at the high concentration applied by the dual application method gave nearly similar results to those obtained by NPK fertilization treatment.
Fruit and yield parameters:
• Different fruit and yield parameters such as fruits number/ plant, fruits fresh weight/ plant, sepals fresh weight / plant, sepals dry weight per plant and per fed. and seeds dry weight per plant and per fed. were remarkably augmented due to NPK fertilization in comparison with the other EM, Minia Azotein and ascorbic acid treatments. Next to NPK treatment was both treatments of the high concentration of EM or Minia Azotein applied as seed soaking plus seedling spray. These two particular treatments did not differ than NPK treatment for fruits number/ plant, as well as, sepals dry weight per plant and per fed. and were slightly behind NPK treatment for the rest of yield parameters.
• On the other hand, ascorbic acid treatments, including high and low concentrations and different methods of application gave the least values of fruits and yield parameters in comparison with NPK, EM and Minia Azotein treatments.
Chemical constituent determinations:
• The three photosynthetic pigments, chlorophyll a, chlorophyll b and carotenoids contents as well as, anthocyanin %, acidity % and herb nitrogen % in roselle plants were greatly promoted due to NPK fertilization treatment. Similar trend of increasing all these chemical determinations, but by lesser extent, was give by EM and Minia Azotein, while ascorbic acid gave the least values, regardless of the used concentration, within each one of the three tested materials ( EM, Minia Azotein and ascorbic acid) the high concentration, as well as, the dual method of application ( seed soaking plus seedling spray) were capable of recording higher values of different chemical constituents than low concentration and other two methods of application.
Recommendation:
* It is recommended, from the economical, environmental and safety product view point, to substitute the conventional NPK fertilization treatment by supplying roselle plants with the high concentration of EM ( 700 cm + 300 cm water) or Minia Azotein ( 500 cm + 500 cm water) as seed soaking plus seedling soil drench.