For the production of 1 kg of rice, about 15,000 litres of water is used in India as against 6,000 litres of water in Japan. One study indicates that about 3000 to 4000 litres of water are enough to produce 1 kg of rice (Pande 1987). The total water application in the fields to rise a rice crop varies from 750 to 2500 mm. Major variations is due to the loss of water, which occurs due to seepage and percolation. The growth duration of rice varies from 100 to 160 days; the atmospheric evaporation demand in different rice growing regions and season varies from 3 mm day-1 to 8 mm day-1. Thus the water requirement of rice crop is about 4 to5 times that of the other cereal crops. The water losses due to percolation, if checked, may bring considerable saving in water resulting in higher water use efficiency.Inefficient management of water in relation to specific soil and environmental conditions appears to be a major constraint limiting rice production in India. Determination of the water requirement and water use efficiency of promising varieties is important for irrigation planning and management.
Effect of land submergence on growth and yield of rice has been studied by several workers for important rice growing tracts of India (Choudhury and Panday 1971; Pande and Mitra 1971; Vamadevan and Asthana 1972; Jha and Asthana 1978), Their findings indicated that a shallow depth of about 5+2 cm submergence is essential for rice growth.A series of trials (Anon 1974) revealed that during monsoon season the rice crop performance was almost similar under saturation, shallow and deep submergence, which may be attributed to low evaporative demand and frequent wetting of the soil due to rains. Whereas in summer season high evaporative demand
Submitted by yogesh on Mon, 24/11/2008 - 10:51