Two field experiments were carried out al the Experimental Farm of Faculty
of Agriculture. Ain Shams University, Egypt during the two seasons of 1999 and 2000
to investigate the effect of Irrigation intervals and different fertilization sources on \he
growth, yield and chemical constituents of roselle plants. Three irrigation intervals, i.e.
Irrigation every 1, 2 and 3 weeks were applied in C'.ombinatlon with 4 mixtures of
chemical and bio-fertilizers which were as follows: Fun dose of NPK-recommended rate: 150 kglfed. ammonium sulphate 0.5%) +
200 kglfe(t calcJum superphosphate (15.5%) + 150 kglfed. potassium sulphate
(48%). 50'10 NPK-recommended rate + 4 kglfed. biogen. 50% NPK-recommended rate -+ 4 kg/fed. phosphorin. 50'10 NPK-recommende fertilized with 50% NPK-recommended rate + biogen + phosphorin produced the
highest values of plant height, number of branches and fnits/plant, fresh ~ighlJ of
fruits and sepals glplant, sepals dry weight (glplant or kglfed.), seed yield (gJplant or
tonlfed.), anthocyanin content as well as N, P and K contents In both seasons. The
lowest pH values (which caused the highest acidity), the highest T.S.S a~ fixed oil
percentages were obtained from the treatment Irrigated every 3 weeks a"'l fertilized
with half dose of NPK·recommended rate combined with both blofertilizers in both
seasons. The treatment irrigated every 2 weeks and fertilized with 500/. NPK-
recommended rate combined with both biofertilizers produced the high t fixed oil
yield glplant and kglfed. in both seasons.