Crop managements need accurate simulation of leaf development, specially in main stem. Thermal interval between the appearance of successive leaf tips (phyllochron) is critical for predicting duration of vegetative development. Quantitative information regarding effects of micronutrients such as Boron, Zinc and Copper on main stem leaf traits of wheat (Triticum aestivum) is scarce. Foliar application can guarantee the availability of nutrients to crops. in order to study of response of wheat phyllochron and leaf appearance rate to foliar application of these micronutrients. tow experimental design were factorial based on randomized complete block design(RCBD) with four replications and experiments conducted at Chenaran and Mashhad, Iran during 2010-11. Treatments of these experiments were Type of elements (Zinc, Boron and Copper) Doses of Foliar application (0, 1 and 2 lit/ha) and Varieties (Gaskojen and Pishtaz). The experiments were conducted under well-watered conditions. The relationship between main stem leaf numbers (HS) versus Growth-Degree-Day was described using non-linear, segmented regression model. The results indicated that significantly the leaf appearance rate therewith phyllochron affected by variety and dose of application in tow locations, and also by type of element in Chenaran,. Leaf appearance rate in Gaskojen was higher than Pishtaz and Certainly phyllochron was lower in Gaskojen. Also higher amount of leaf appearance rate was for highest dose of Zinc and Boron foliar application (2 lit/ha) at tow locations. Leaf appearance rate in Chenaran (0.0089) was higher than Mashhad (0.0081), and phyllochron and the time of cessation in leaf production were lower than this. Phyllochron in Chenaran was 113 Growth-Degree-Day, and also Chenaran with 8.25 was paramount than Mashhad with 8.07 in final leaf number in main stem. The findings found at this study can be used in management recommendations of wheat. Further, it was recommended that more attention should be paid to apply of Zn and B fertilizer in mentioned locations.
