Effects of Foliar Application of Zinc Sulphate and Boric Acid at Different Phenological Stages on Yield and Growth Characteristics of Two Rapeseed Cultivars)Brassica napus L. (

This experiment was carried out as a factorial design based on RCBD with 18 treatments and three replicates during crop year 2005-2006 at Zanjan agricultural research center, in order to investigate effects of boron and zinc foliar application on yield of two rapeseed cultivars. Factors in the experiment were: spraying Zn sulphate at three levels including Zn0 (no spraying), Zn1 (spraying with concentration of 0.003m/v), Zn2 (spraying with concentration of 0.006 m/v) and spraying boric acid including B0 (no spraying), B1 (spraying with concentration of 0.002 m/v), B3 (spraying with concentration of 0.004 m/v) and the two cultivars were V1 (SLM046) and V2 (Talayeh). Sprayings were accomplished at two growth stages (early stemming and flowering). During the growth period, conventional cares were done and the required information including plant height, number of fertile and infertile capsules were recorded. At harvesting, TKW (thousand kernel weight) was determined in addition to grain yield. Analysis of variance showed significant difference between the treatments, Maximum grain yield of rapeseed (4180 kg/ha) was obtained from Zn0B1 treatment in SLM046 cultivar. Therefore, regarding to positive effects of B on grain yield and joint application of B and Zn on the number of fertile and infertile capsules and TKW and also high yield, it is recommended to use cultivar SLM046 and joint spraying of boric acid and Zn sulphate with the concentration of 0.002 and 0.003(m/v), respectively, at early stemming and flowering stages in the regions of similar climate.