University of Guilan Cereal Research 2252-0163 2 3 2013 01 21 The effect of salinity stress and irrigation regimes on yield and water productivity in cracked paddy rice field The effect of salinity stress and irrigation regimes on yield and water productivity in cracked paddy rice field 193 208 1656 FA Ali Ashraf Sadradini Assoc. Prof., Dept. of Water Engineering, Faculty of Agriculture, Tabriz University Fatemeh Salahshour Dalivand Ph.D. Student of Irrigation and Drainage, Faculty of Agriculture, Dept. of Water Engineering, Tabriz University Journal Article 2012 09 04 The most common irrigation method for Iran's paddy rice fields is continuous flooding that it changes to intermittent irrigation in water shortage. On the other hand, several droughts and also construction and operation of different dams in Sepidroud River watershed cause to decrease the water quality of this river in the recent years. In this study the combined effects of salinity and drought stresses were investigated on horizontal and vertical water flow in cracked soil of a Hashemi cultivar paddy field (most common cultivar in Guilan Province). Treatments were consist of two irrigation strategies, namely continuous and intermittent (6 days intervals) flooding methods by applying 5cm water height and three salinity stress by using irrigation water at three electric conductivity levels of 2, 3 and 4 dsm^-1. These treatments applied in two conditions consist of crack width 3 mm and 2 cm. The results indicate that when cracks by average width of 2 cm form in paddy field, daily irrigation of the crop even with inferior quality water can cause to higher yield than intermittent irrigation. In spite of less irrigation water for 6 days interval treatments, continuous irrigation treatments with 3 mm width cracks had the highest water productivity. Also, cracks by average width of 2 cm, increase lateral flow significantly. The effect of irrigation water salinity on lateral flow rate was not significant and cracks became irreversible even after rewetting. The most common irrigation method for Iran's paddy rice fields is continuous flooding that it changes to intermittent irrigation in water shortage. On the other hand, several droughts and also construction and operation of different dams in Sepidroud River watershed cause to decrease the water quality of this river in the recent years. In this study the combined effects of salinity and drought stresses were investigated on horizontal and vertical water flow in cracked soil of a Hashemi cultivar paddy field (most common cultivar in Guilan Province). Treatments were consist of two irrigation strategies, namely continuous and intermittent (6 days intervals) flooding methods by applying 5cm water height and three salinity stress by using irrigation water at three electric conductivity levels of 2, 3 and 4 dsm^-1. These treatments applied in two conditions consist of crack width 3 mm and 2 cm. The results indicate that when cracks by average width of 2 cm form in paddy field, daily irrigation of the crop even with inferior quality water can cause to higher yield than intermittent irrigation. In spite of less irrigation water for 6 days interval treatments, continuous irrigation treatments with 3 mm width cracks had the highest water productivity. Also, cracks by average width of 2 cm, increase lateral flow significantly. The effect of irrigation water salinity on lateral flow rate was not significant and cracks became irreversible even after rewetting. https://cr.guilan.ac.ir/article_1656_56910922aea58b6e76e97ee4df26991d.pdf