**2. Rice ecological conditions**

Rice plant water requirements is based on ecosystems under which it is cultivated. When it is grown as an upland crop under rain-fed conditions it needs 100 mm monthly rainfall and when grown as lowland crop it requires 200 mm rainfall per month. Rice can also be grown as lowland crop with standing water. Rice crop will need 125 mm monthly rainfall during vegetative stage while during ripening stage no standing water is needed. It is thus best adapted to grow with abundant water supply [12]. Rice grows in different soil conditions ranging from black clay that is heavy to sandy loam with a pH range of 4.5–7.0 and can tolerate water logged soils. Hot and humid condition with temperature ranging between 22o centigrade to 40o centigrade is the ambient climatic condition of rice. It grows well in altitudes of between 0 and 1700 meters above sea level [13].
