Interaction of Plant Growth Regulators and Mineral Nutrients on Seedling Growth of Volkamer lemon (Citrus volkameriana Pasq.) Rootstock before Grafting in the Nursery

Commercial production of uniform and healthy seedlings to be used as a rootstock in a controlled environment has become commonplace. Any attempts to enhance their growth and shorten the preparing period for grafting will be of value and reduce the cost of production.  The aim of this study was to investigate the interaction of growth regulators including gibberellic acid (GA3) with a concentration of 0 and 100 mg L-1 and subsequently paclobutrazol (PBZ) with a concentration of 0 and 500 mg L-1 and nutrient sources of urea 0 and 0.5% and nickel sulfate 0 and 150 mg L-1 on seedling growth of volkameriana. Results indicated that 100 mg L-1 GA3 accompanied by 0.5% urea and 150 mg L-1 nickel sulfate significantly increased stem length and treatment combined with PBZ 500 mg L-1 gave the highest rate of stem diameter.