An experiment was conducted in two successive seasons to study the effect
of ornithine and phenylalanine ( 100.200 and 400 ppm) on growth. carbohydrates.
pigments and alkaloidal content of Datura innoxle Mill leaves at flowering stage. The
highest value of plant height and number of branches or leaves were obtained from
plants treated with 200 ppm ornithine and phenylalanine. Plants treated with 400 ppm
ornithine and 200 ppm phenylalanine gave the highest value of leaf area and dry
weight of leaves. The application of amino acids. omithine and phenylalanine resulted in low
levels of soluble as well as, non soluble suqars and total carbohydrate of Oatura
leaves as compared to the control. While the same treatment gave the highest level of
chlorophyll a and b, whereas carotenoids were decreased due to applications of low
concentrations of omithine and phenylalanine. Ornithine and phenylalanine showed a stimulatory effect on leaf chemical composotions such as nitrogen, protein, RNA, DNA and alkaloidal content. The highest values of theses contents were obtained from ornithine at 400 ppm and phenylalanine at 200 or 400 ppm.