RESPONSE OF SUNFLOWER TO DIFFERENT LEVELS OF ZINC AND IRON UNDER IRRIGATED CONDITIONS

Two field experiments were conducted at National Agricultural Research Centre, Islamabad during spring seasons 2002-03 to evaluate response of sunflower (Helianthus annus L.) to different levels of zinc and iron under irrigated conditions. Three levels of zinc 0, 5 and 10 kg ha-1 and three levels of iron 0, 2.5 and 5 kg ha-1 were applied in soil to see their effect alone and in different combination on grain yield, oil contents, other agronomic parameters and concentrations of zinc and iron in leaves of sunflower. Highest grain yields (2743 kg ha-1) and 1000-seed weight were obtained in treatment that received combined application of 10 kg zinc and 5 kg iron ha-1. Addition of 0, 2.5 and 5.0 kg ha-1 iron and 5.0 kg ha-1 zinc alone increased yield non-significantly as compared to control. The combined application of zinc + iron at 5.0 kg ha-1 produced significantly (P . 0.05) higher yield than control but was similar to the lower doses. Highest plant height (167.0cm) and greater head diameter (17.6 cm) and highest oil contents (39.7%) were achieved with the application of 10 kg zinc and 5 kg Iron ha-1. The concentrations of zinc and total iron in the leaves were increased with zinc and iron application. Maximum concentration of zinc (70.5 mg kg -1) and iron (553.5 mg kg -1) in leaves was recorded with application of 10 kg zinc + 5 kg iron ha-1. The results of this study suggest that soil application of 10 kg zinc and 5 kg iron ha-1 has a positive affect, both quantitative and qualitative on yield of sunflower under irrigated conditions.