Water use efficiency of micro and furrow irrigation systems in single and two-row planting systems of grain corn.

Water is the most important agricultural constraints and have to used wisely. A field experiment was conducted at the Miyandoab Agricultural Research and Natural Resources Station to study water use efficiency (WUE) of furrow and micro irrigation systems (strips of drip tape irrigation) and single-row and two-row planting systems of grain corn SC 704. The experimental design was randomized complete blocks arranged in Strip Split Plots with three replications for three years (2005-2007). Irrigation treatments were placed in vertical plots and planting array of different densities were placed in horizontal plots in form of split plots. The vertical plots was comprised of four irrigation treatments, including: three levels (80%, 100% and 120%) of water requirement by use of drip tape irrigation and 100% of water requirement in furrow irrigation. The horizontal factor was planting array in the form of single-row and two-row planting and the (secondary) sub factor was comprised of three levels; 75, 90 and 105 thousand plants per hectare. In this research the impact of different factors on the water use efficiency, grain yield, dry biomass and 1000-kernel weight were studied. The results showed that in irrigation treatments the WUE in drip tape irrigation of 80 and 100% had greatest values, but in furrow irrigation treatments it had the least value. The grain yield in drip tape irrigation at 120% of water requirement had the greatest value and at 80% of water requirement it had the least value. In case of planting array, the values of WUE and grain yield in two-row planting system were greater than those in single row planting system. In case of density, WUE and grain yield of the density 90000 plants per hectare had the greatest values and those of 75000 plants per hectare had the least values. In terms of the interaction between irrigation and density, WUE had the greatest value in the treatment tape drip irrigation at 80% of water requirement and 90000 plants per hectare. In terms of the interaction between irrigation system, planting array and density, WUE in the treatment drip tape irrigation at 80% of water requirement and two-row planting system with 90000 plants per hectare had the greatest value and in the treatment furrow irrigation it had the least value.