Study of water productivity on transplanted rice cultivation (tarom and shiroodi variety).

Rice is the most important cereal crop after wheat in the world.It is the biggest consumer of water due to it's Specific condition of cultivation and has lower water use efficiency among other agricultural crops. In order to determine water productivity in transplanted rice cultivation(Tarom and Shiroodi varieties),a field experiment was conducted at the rice Reaserch Institute of Iran, Deputy of mazandaran. The experimental design was completely blocked design with five irrigation tereatment in three replication. tereatmen included: 1-Fully submerged, 5cm depth throughout growing season. 2-alternate irrigation o-5cm throughout growing season. 3-Irrigation, 5cm depth 2 days after disappearing of water from soil surface. 4- Irrigation, 5cm depth 5 days after disappearing of water from soil surface. 5-saturated soil throughout growing season. Consume water measured by using flow meter, installed in the irrigation pipe.with the yield and water consumption in each treatment, CPD index was calculated. Then On the basis of crop price and all costs, net benefit in the different level of irrigation and so NBPD index was calculated. On the basis of both productivity index analysis, there is Significant difference between treatments with the maximum in T5 and mimimum at T4. result showed in tarom there was 30% reduction of water use in T5 as compard to T1, while yield reducted 8% and net benefit reduction was 15%. Also in shiroodi variety. The reduction of water in T5 was 15% compared to T1, whereas the reduction of net benefit and yield were about 8% and 4% respectively. Effect of different irrigation amounts on yield component such as, harvest index, plant height, full grain, Leaf Area Index(LAI), also were measured and have been discussed. Key words:Water Productivity, Rice, Alternate Irrigation, deficit irrigation.