This study was carried out at the Experimental Nursery of the Ornamental Horticulture Department, Faculty of Agriculture, Cairo University, Giza, during the two successive seasons of 2000 and 2001, with the aim of investigating the effect of chemical, organic and bio-fertilization treatments on the growth and chemical composition of Joseph's coat (Amaranthus tricolor L.) plants.
The treatments included fertilization with PK (P at 6 g calcium superphosphate, and K at 3 g potassium sulphate / 25-cm clay pot), combined with: (1) N fertilization at the rates of 6 or 12 g ammonium sulphate /pot (N1 and N2, respectively), (2) Bio-fertilization (Bio), (3) Bio. + half the previous N fertilization rates (½ N1 or N1), (4) Cattle manure (CM) at the rate of 710 cm3/pot (equivalent to 40 m3/feddan), or (5) Bio + CM at 355 cm3/pot (equivalent to 20 m3/feddan). Control plants received PK fertilization only. The bio-fertilizer was applied to the soil as a liquid inoculum containing Azospirillum brasilense, Klebsiella pneumonia and Pseudomonas putida. Most of the fertilization treatments increased the different vegetative growth and flowering characteristics. Among the different treatments, combining Bio with CM (i.e. PK + Bio + ½ CM) was the most effective one, giving the highest values for plant height, stem diameter, leaf area, number of flower stalks/plant, fresh and dry weights of leaves and stems/plant, as well as the the highest contents of chlorophyll “a", total chlorophylls (a+b), carotenoids and anthocyanin in the leaves. Also, this treatment (PK + Bio + ½ CM) gave the highest content of total carbohydrates in the leaves, stems, flowers and roots (in most cases). On the other hand, PK+N2 gave the highest numbers of branches /plant, and the longest flowering stalks, while the highest number of leaves was found on plants fertilized using PK + N2 or PK + ½ CM + bio-fertilization. PK + N1 + Bio gave the highest roots fresh weight in both seasons. Plants fertilized with PK + N2 had the highest N content in the leaves (in both seasons), stems and flowers (in the first season), as well as the highest P content in the roots (in both seasons) and stems (in the second season).
It was concluded that, for best vegetative growth and flowering of Amaranthus tricolor, L. the plants should be fertilized using the previously described mixture of PK, bio-fertilization and half of the full dose of organic (cattle) manure.