Effects of drought and salinity on yield and water use efficiency in pomegranate tree

About half of the irrigated land in the world is affected by salinity and sodium or flooding. both salinity and drought stress cause plants limited access to water and reduction of the growth rate of plants is associated with metabolic changes. pomegranate is one of the plants that are planted in arid and semi-arid areas. pomegranate is native to iran and has highest acreage in the producing pomegranate among countries. to study the combined effects of salinity and drought stress on water use efficiency and crop yield in years 2010-2011 and 2011-2012 pilot projects at the islamic azad university of ferdows on four years pomegranate trees was carried out. key factors include five different irrigation amount and three levels of irrigation water salinity. at the end of the second year total yield and efficiency of pomegranate juice consumption was measured. the results showed that the crop yield and water use efficiency significantly affected by salinity and drought stresses were applied in combination. the study of separate effects of stress showed that deficit - irrigation causes a significant decrease in crop yield compared to full irrigation if the salinity stress had no significant effect on crop yield. in general it can be said that the pomegranate tree is susceptible to dehydration and resistant to salt stress. the calculations showed that salinity stress can reduce water use efficiency. drought stress on water use efficiency did not decrease as much as 10% but greater amounts of deficit irrigation reduced water use efficiency.