Effect of some mineral nutrients on vegetative growth, chemical constituents, and anatomical structure of Grevillea robusta seedlings.

This study was carried out in the Experimental Nursery of Ornamental Horticulture Department, Faculty of Agriculture, Cairo University, Giza, and the chemical analyses were carried out in laboratories of the National Research Centre, during two seasons the 2014-2015 and 2015-2016 to investigate the response of Grevillea robusta A. Cunn. seedlings to some treatments of mineral nutrients: zinc (Zn) at 50 and 100 ppm, cobalt (Co), nickel (Ni), and selenium (Se) at 5 and 10 ppm. , Uniform seedlings with an average 25cm height and 0.35 cm stem diameter were planted in 35 cm plastic pots, filled with a sandy loam soil were used in this study. The treatments were applied individually as a foliar spray every month, in both seasons throughout the period of growth. Plants were sprayed with Zn at 100 and 50 ppm produced the tallest plants, the thickest stem and main root as well as the heaviest fresh and dry weights of all plant parts. The plants treated with Ni at 10 ppm gave the maximum numbers of leaves and the longest roots. Spraying plants with Ni at 10 and Se at 5 ppm increased the content of chlorophyll-a, b and total carotenoids, while treating seedlings with Zn at 50 and 100 ppm increased the total carbohydrates, N%, P%, K% and Zn (ppm). The plants produced the maximum concentration of Co (ppm) when they were sprayed with Co 10 and 5 ppm, however the concentration of Ni (ppm) were increased markedly in response to 10 and 5 ppm of Ni treatments. Study the anatomical structures of the transverse and the longitudinal sections of main stem of G. robusta were showed an increments by treated with Zn at 100 ppm as compared with untreated plants.