Effect of different irrigation regimes, residues and tillage on yield, yield components and cotton water productivity in the temperate zone of Khorasan Razavi

Effects of different irrigation levels on yield, water consumption, water use efficiency and agronomic characteristics of cotton-wheat crop rotation system products under the conservation agriculture system were examined in the temperate zone of Khorasan Razavi. The study was conducted in agricultural and natural resources research station of Gonabad using split split plot based on a randomized complete block with three replications in 2015. This research with three factors: a- tillage method at three levels (no-till, conventional tillage and reduced tillage) b- Residue management at three levels (without residue, maintain 30 percent of the debris and keep 60% residue) c- different levels of water irrigation at three levels (50, 75 and 100% of irrigation water requirement). The tillage method was treated in the main plot, the residue management treatment in the sub-plot and the different levels of irrigation water in the sub-plots. In this study, the common and suitable cultivar of the region, called Khordad, was used and drip irrigation method was used as a tool for uniform distribution and accurate measurement of water. In this study, drip irrigation was used as a suitable tool for uniform distribution and accurate water measurement. The results showed that the highest grain yield of cotton wheat was obtained from treatment of conventional tillage with 60% residue and applying 75% of the irrigation water requirement as 3576 kg/ha that there was no statistically significant difference with treatment of no tillage with 60% residue and applying 75% of the irrigation water requirement as 2568 kg/ha. The highest water use efficiency of cotton was obtained from treatment of conventional tillage with 60% residue and %50 of the irrigation water requirement as 0.58 kg/m3. Regarding the non-significant of reduction in cotton yield under 75% of the irrigation water requirement was compared to the control, and due to the increased in water use efficiency under 75% of the irrigation water requirement was compared to the control, if needed to save water consumption (Due to lack of water resources in the country) application of 75% irrigation water requirement for cotton is recommended in agricultural conservation conditions.