Combined effect of Zinc and Boron on yield and nutrients accumulation in corn

The event of partly grain-free ear is a crucial problem which can result in severe reductions in corn yield. In a two year field investigation, during 2003-2004, an experiment was conducted to determine the effect of  boron (B) and zinc (Zn) application on yield and yield components of corn (Zea mays L.) plants grown in a B and Zn-deficient calcareous soil (fine, carbonatic, thermic, Typic Haploxerepts) of southern Iran. Treatments consisted of five levels of Zn (soil application of zinc sulfate at the rates of 0, 8, 16 and 24 kg ha-1 and foliar spray of Zn solutions containing 0.3 weight percent of zinc sulfate) and four levels of B (soil application of boric acid at the rates of 0, 3 and 6 kg ha-1 and foliar spray of B solutions containing 0.1 weight percent of boric acid). Zn and B solutions were applied at the rate of 1000 L ha-1.  Zn and B fertilization significantly increased plant biological yield, grain yield, thousand grain weight, number of grains per stalk, grain protein content and the concentration of B and Zn in corn tissues. There was a significant B × Zn interaction on corn yield and tissue nutrient concentrations. In general, the effect of B × Zn interaction was synergistic on corn growth and yield. Although B and Zn fertilization made significant changes in some plant nutrients, the changes were slight enough not to affect plant growth and production. It was concluded that the event of partly grain- free ear in corn is proportionally related to B and Zn deficiency in calcareous soils of southern Iran.  It can be recommended that in calcareous soils of southern Iran with low levels of available Zn and B, soil application of 16- 24 kg ha-1 of zinc sulfate and foliar application of B solution containing 0.1 weight percent of boric acid (1000 L ha-1) may be applied for enhancement of grain yield and reduction of partly grain-free ear in corn. Further, it is recommended that more attention should be paid to Zn and B nutrition of corn plants in calcareous soils having low availability of these tow nutrients.