Effect of Different Crop Rotation Systems on Wheat Productivity in Cold Agro-Climatic Region of Khorasan-e-Razavi in Iran

To evaluate variation in grain yield and its components and growth characteristics of wheat in different crop rotation systems a field experiment was carried out using randomized complete block design with three replications at Agricultural Research Station of Jolgeh Rokh، Khorasan-e-Razavi province، Iran، in 2005-10. Five crop rotation systems included; wheat monoculture for the whole period (WWWWW)، wheat-wheat-wheat-rape-wheat (WWWRW)، wheat-sugar beet-wheat-sugar beet-wheat (WSWSW)، wheat-potato-wheat-potato-wheat (WPWPW)، wheat-potato-wheat-rape-wheat (WPWRW)، wheat-sugar beet-wheat-potato-wheat (WSWPW)، wheat-maize-wheat-potato-wheat (WMWPW)، wheat-maize-wheat-sugar beet-wheat (WMWSW). The lowest economic yield in the final year belonged to wheat monoculture as compared to the other crop rotation systems. Increment of 21-37% in grain yield، rotation index and water productivity for wheat and decreasing of 51-90% in weed dry matter in crop rotation treatments compared to wheat monoculture showed the positive effects of appropriate crop rotation systems. The average water productivity on the basis of economic dry matter were 2. 33، 1. 60، 0. 78، and 0. 79 kg m-3 for corn، sugar beet، potato، and rapeseed، respectively. The average water productivity on the basis of wheat economic dry matter were 0. 87، 1. 09 and 1. 56 kg m-3 in the first، third and fifth year، respectively. Rapeseed and potato were more effective on the productivity of wheat as compared to the other field crops.