Effect of Deficit Irrigation and Partial Root – Zone Drying on Yield and Water Use Efficiency of Two Potato Cultivars

Introduction: Potato is one of the main products of agriculture in feeding the world's population and agricultural economy. The production of potato in the world occupies the forth place after wheat, rice and corn. In Iran, annual production of more than 5.5 million tons potato, has made this crop the most important food after wheat. On the other hand, in arid and semi-arid regions, water is the most important limiting factor for production of agricultural crops such as potato. Considering the water use efficiency is one of the most effective ways to deal with the water crisis and increasing the quality and quantity of agricultural productions. Production increasing per unit of water consumed (increasing water productivity) by improving the selection of plant varieties, irrigation management and use of new irrigation methods may be feasible. Material and Methods: The research was performed in the Chahartakhteh research station (32° 18' N. and 50° 55' E.) with 2090 m height above sea level and semi-humid climate with moderate summers and cold winters. Average annual rainfall is about 320 mm mostly during winter. The soil moisture and temperature regimes are Typic Xeric and Mesic, respectively. Soil texture is silty clay. In order to determine the best method of deficit irrigation for optimizing water use efficiency and yield of two potato cultivars, an experiment was performed in Agricultural and Natural Resources Research Center of Chaharmahal va Bakhtiari farm in 2013. The experiment was based on randomized completely blocks with split - split plot design in three replications. The furrow and tape drip irrigation methods were as the main plots, two potato cultivars as sub plot units and four deficit irrigation managements as the secondary sub plot units including CI(100%), RDI80(80%), RDI65(65%) of available water depletion (AWD) and partial root-zone drying (PRD) during full growth period. Almera and Burren cultivars are two new cultivars of high yield and quality of early growth period of approximately 90-80 days, high compatibility with Chaharmahal va Bakhtiari climate and more regions of Iran. Results and Discussion: Analysis of variance (ANOVA) of studied factors showed that the deficit irrigation management on tuber yield (ton/ha), tuber yield per plant, the amount of starch, soluble sugar, proline, chlorophyll, water use efficiency, and water productivity were significant (P≤0.01). Effects of cultivar on tuber total yield, tuber yield per plant, so