Two greenhouse experiments in Randomized complete block design with four replications were conducted at Soil, Water and Bioenergy Resources, South Centers, Piketon, OH, Ohio State University, USA, to study the effect of iron forms (conventional Ferric chloride (FeCl3- 6H2O),chelated iron(6% Fe) and Nano Iron Oxide (Fe2O3, alpha, 99%,)at different doses(0, 50 and 100 mg/kg-1 soil) on growth, anatomy and early yield in cucumber plants (Cucumus sativus L.) cv.(Tyria F1) during 2015 and 2016 seasons. Results showed that, the different applied treatments increased plant height, leaf number, leaf area (LA) (cm2), fresh weight and dry weight at60 and 90 days after transplanting during the both seasons of cultivation. Also, anatomical studies were carried out on stems i.e.( stem thickness, xylem and Phloem thickness, and numbers, cambium region thickness, Fiber tissue thickness and pith thickness) and leaves measurements i.e.( plaside and spongy tissue and xylem thickness, number of vessels and phloem at 30 days of plant age in the second season. Data showed positive response to the different applied treatments especially with nano iron at 100 mg/kg-1.In addition, early fruits number/plant, fruit length, fruit diameter and early fruit weight per plant increased due to the different applied treatments in the first and second seasons. Results also, showed that soil application of nano iron at 100 mg/kg-1 is the most effective treatment in this respect compared with other tested iron sources and control treatments |