STUDIES ON THE RESPONSE OF ROSELLE PLANTS TO DIFFERENT NITROGEN FERTILIZERS IN CALCAREOUS AND SANDY SOILS

Abstract

This work ainted to study the effect of different nitrogen sources and row spacing on the growth and productivity of roselle plants (Hibiscus sabdariffa L) cultivated under the conditions of calcareous• and sandy soils in the Newly reclainted lands of Egypt .A feild experintent was carried out in two different locations representing Newly Reclainted lands in the west desert of Egypt (Nobaria and Wadi El-Natron) in comparison with the old cultivated lands in the Nile Valley (Giza). The experintent included nine treatments wich were the combination between three nitrogen forms (urea, ammonium nitrate and ammonium sulfate) and three row spacing (45, 60 and 75 em). The irrigation system used in both Nobaria and Wadi El-Natron was the centtral spraying system (pivot system). Another experintent has beeen carried out in Wadi El-Natron in 1994 included two irrigation methods (drip irrigation and pivot system) and two selected row spacing (45 and 75 em). The desigen of the experintent was split plots with fom replications. The effect of different nitrogen sources was significantly only on tlte dry weight of!eaves (g/plant) at maturity stage in sandy soil in 1993, wich the heaviest dry weight was obtained with application of urea.ln the second season ,the nitrogen forms had an effect on plant height in both soils, dry weight of stem (g/plant) ,number of fruits per plant ,weight of dried sepals and seeds (g/plant) in Wadi El-Natron. Application of ammonium nitrate gave the tallest plants, the highest number of fiuits, the heaviest dry weight of sepals and seeds (g/plant). Cultivation at 60 em between rows in both soils significantly increased dry weight of sepals (g/plant) in1993.