A Determination of Suitable Interval and Depth of Irrigation in Canola Crop as Based on Evaporation from Class A Pan (Case Study: Bushehr, Iran)

Proper irrigation scheduling, i.e. timely and adequate irrigation is an important prerequisite to profitable crop production. High temperatures along with soil moisture deficits are some of the main limiting factors for Canola (B. Napus L.) production in dry land cropping systems. These factors negatively affect the formation of pods during the flowering stage, resulting in decrease in seed yield. This experiment was carried out to determine the rate of water consumption, and come up with a proper irrigation scheduling of canola crop in semi-arid conditions of Bushehr province. The experimental design was an RCB one with four irrigation treatments (irrigation after 50,70, 90 and 110 mm of cumulative evaporation from class A pan) in three replications from 2001 to 2003 in Agricultural Research Station of Bushehr. The results revealed that by increasing the irrigation interval, seed yield, oil yield and water use efficiency decreased, but no significant difference was observed between 50mm and 70mm treatments. However, treatment 70 mm is recommended because of lower water usage, leading to more feasibility for the growers. In General, the results of the study indicated that for seed yield of 1.2 t/ha, oil yield of 545 Kg/ha and WUE of 2.1 kg/m3, it is required to use 561mm of water (including the effective rainfall) through at least 10 times of irrigation or rainfall events with 50 mm each time during the growing season.