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Abstract:
The amounts of consumptive water requirements (ETC) for premature and serotinous varieties of rice were calculated at ten stations in the Mazandaran Plain, based upon evapotranspiration amounts (ETO) and plant growth coefficients (KC). Then the effective rainfall amounts (ER) and the groundwater amounts, absorbed by plants’ roots (GWC), were calculated according to the most suitable methods. The net irrigation requirement (IR) is defined as the subtraction of ER and GWC amounts from ETC amounts.
The results of the study showed that the ETC and IR amounts are more in the stern part of the plain than the western part; wereas ER amounts are more in the western part. ER has more proportion of ETC in the western part; wereas this proportion is less in the east. ER amounts are much less than IR amounts in the whole region
Key words: effective rainfall , irrigation requirement , consumptive water requirement , rice , Mazandaran Plain