Physiological Effect Of Phenylalanine And Tryptophan On The Growth And Chemical Constituents Of Antirrhinum Majus Plants

Abstract

A pot experiment was carried out in the nursery of the National Research Center, during the two successive seasons of 2007/2008 and 2008/2009, with the aim of studying the effect of foliar application of the amino acids phenylalanine and tryptophan (each at the rate of 50 or 100 ppm), applied separately or in combinations of the different concentrations (plus untreated plants), on the growth and chemical constituents of Antirrhinum majus plants. Results showed that, increasing the two amino acids concentrations gradually increased significantly all growth parameters, vegetative and flowering stages (plant height, number of branches, fresh and dry weights of plant as well as length of inflorescence, number of inflorescences/plant and fresh and dry weights of inflorescences/plant), and the contents of the photosynthetic pigments, total soluble sugars and total free amino acids in the leaves. The effect of tryptophan was superior to that of phenylalanine on increasing plant growth at vegetative growth. The maximum plant growth as determined by all the recorded parameters as obtained from plants treated tryptophan and phenylalanine at rate of 100 ppm); separately or in combined between them gave the best results than the others treatments and untreated plants.