RESPONSE OF SUMMER ANNUAL FLOWERING PLANTS TO CHEMICAL, ORGANIC AND BIO-FERTILIZATION TREATMENTS. II- AFRICAN MARIGOLD (Tagetes erecta L.) PLANTS

Abstract

, during the two successive seasons of 2000 and 2001, with the aim of investigating the effect of chemical, organic and biofertilization treatments on the growth, chemical composition and oil production of African marigold (Tagetes erecta L.) plants. In addition to the control, the fertilization treatments included: (1) N fertilization at the rates of 6 or 12 g ammonium sulphate /pot (N 1 and N 2 , respectively), (2) Bio-fertilization (Bio), (3) Bio + half the previous N fertilization rates (½ N 1 or N 1), (4) Cattle manure (CM) at the rate of 710 cm 3 /pot (equivalent to 40 m 3 /feddan), or (5) Bio + ½ CM (i.e., CM at 355 cm 3 /pot, equivalent to 20 m 3 /feddan). All plants (including the control) received chemical PK fertilization (P at 6 g calcium superphosphate, and K at 3 g potassium sulphate / 25-cm pot). The bio-fertilizer was applied to the soil as a liquid inoculum containing Azospirillum brasilense, Klebsiella pneumonia and Pseudomonas putida. In general, all the tested fertilization treatments had a favourable effect on vegetative growth, flowering, chemical composition and oil production. In most cases, fertilization with CM (especially when added without bio-fertilization) gave the highest values for the different vegetative growth characteristics (plant height, number of branches, fresh and dry weights of leaves, stems and roots). Also, CM (with or without biofertilization) gave the best results for number of flowers/plant, as well as fresh and dry weights of flowers (in most cases). Fertilization treatments also increased the leaf contents of chlorophylls "a", "b", total chlorophylls, carotenoids and xanthophylls (in most cases), as well as the total carbohydrates contents in the different plant parts. Also, most of the fertilization treatments increased the N and P contents in the flowers and roots, as well as the K contents in leaves and stems. Moreover, oil percentage and yield were increased in the flowers and leaves of fertilized plants (compared to the control), with the highest values resulting from plants supplied with CM, with or without biofertilization (especially in the second season). Linalool, limonene, ocimene, caryophyllene and eugenol were the main