THE EFFECTS OF SEED RATE AND NITROGEN-FERTILIZATION ON YIELD AND YIELD COMPONENTS OF 2-ROW BARLEY

The effects of seed rate (60-150:kg ha(-1)) and nitrogen fertilization (N) (0-150 kg N ha(-1)) on the productivity of two-row barley was investigated in field trials for six growing seasons (1987-93) under rainfed conditions in Cyprus. Over all years and nitrogen rates, the highest seed rate increased barley grain yield by 6 per cent, while over all years and seed rates nitrogen fertilizer increased yield by up to 25 per cent. At the low seed rate it was possible to reach the maximum grain yield obtained under these growing conditions by the addition of N fertilizer. With low N rates, increasing the seed rate did not significantly increase grain yield. High seed rates and rates of N fertilization, suppressed yield, due to the negative effect on number of seeds per spike and on the weight of the individual grains. Low seed rate (140 kernels m(-2)) is recommended in seasons when establishment is assured by early rain, and an intermediate seed rate (240 kernels m(-2)) is recommended in years when establishment may be reduced. These seed rates should be associated with the optimum N fertilization recommended for the site.