ANBAR JOURNAL OF AGRICULTURAL SCIENCES

Abstract

This experiment was carried out in the lath house, Department of Horticulture, College of Agriculture, University of Baghdad during growing season of 2004. Sour orange, mandarin and grapefruit seedling with 6 months old were foliar sprayed with CuSO4. H2O at a rate of 1 gm/ l. water and ZnSO4. H2O at a rate of 2 gm/ l water while the control treatment was sprayed with distilled water. After two weeks half the number of the seedlings were inoculated with Phytophthora citrophthora to investigate the influence of these chemicals in controlling the gummosis in these different rootstocks through their vegetative growth. The experimental results shows that the type of rootstock influenced the vegetative growth parameters.i.e. Soure orange seedlings significantly characterized by the highest number of root branches 41.64 branch/ seedling. Mandarin rootstocks shows the highest plant height of 28.95 cm and root length of 15.01 cm. Grapefruit rootstocks gave the highest dry weight of vegetative and root growth from the other types (2.02 gm, 1.12 gm/ plant).
The treatments were significantly influenced the all rootstocks by increasing or decreasing average growth rates. Spraying plants without inoculation (T3) causes 16.14% an increases in leaf area and the average of plant height by 11.07% and the average number of root branches by 21.64% and average of root length by 13.18%. The interaction between the types of the rootstocks and the chemicals indicated that grapefruit seedling sprayed with Zn was superior in the height of plant, dry weight of vegetative and roots growth, leaf area, while the interaction between foliar sprays with Zn and inoculation and the mandarin gave the highest root length. The same treatment with sour orange seedling gave the highest number of root branches.