Dryland Wheat Grain Yield and Yield Components as Affected by Slope Direction and Residue Rates

Limited information is available on the effect of residues rates and slope direction on dryland wheat (Triticum aestivum L.) yield.  This study was carried out to determine the effects of residues rates and tillage direction on grain yield and yield components of the Sardary wheat in a dryland region in Zanjan. Five wheat residues rates (0, 25, 50, 75 and 100% surface cover) were applied and incorporated into soil in two slope directions (along the slope and on contour lines) using the randomized complete blocks design with three replications in a land with 10% slope steepness. Overall, thirty plots with 2m × 5 m dimensions were installed in the field and wheat grain yield and yield components were determined for growth period from 2015-2016. Results indicated that grain yield and yield components were significantly affected by the residues rates and slope direction and their interaction. In contour tilled plots, wheat grain yield (1.78 to per hectare), thousand grain weight (42.26 kg) and wheat height (55.11 cm) were 5.32, 5.01, 16.19 and 1.36 percent more than the plots tilled along the slope. The highest grain yield was found in 75% of residue (2.45 ton per hectare) under contour line direction which was about 53% bigger than control treatment (0% straw mulch) under along the slope. This study indicated that the application of straw mulch before cultivation and incorporating into soil using contour line tillage are proper soil management methods to obtain higher wheat yield in this dryland region.