Plant material and growth conditions
Pot experiment was carried out during the successive years 2009-2010 under greenhouse conditions.
When, offsets of Aloe vera had 18-20 cm length and their weight was 100-125 gr, these seedlings were
left to grow in each pot (12 inches in thickness and of 12 inches in height) which contained 20 kg soil.
The experiment was arranged in on complete randomized block design (RCBD) with four replications.
Treatments included four levels of Nitrogen from Urea source (N1: control, N2:500, N3:1000 and
N4:1500 mg pot-1) the fertilizers were added every three months during the 12 month experiment. The air
temperature in the greenhouse was regulated at a maximum of 28oC for the day and a minimum 22oC for
night during the growth period. The used soil was homogenous and the results of its analysis are
presented in Table 1. Also plants were irrigated according field capacity during the period of the
experiments. After one year of growth, five plants per treatment were randomly selected and four leaves
per plant were harvested.