water use efficiency in medicinal pumpkin (cucurbita pepo l. var. styriac)/ chickpea (cicer arietinum l.)- lentil (lens esculenta moench.) intercropping system associated with several nitrogen levels

although the physiological and morphological differences between intercropped species caused a higher wue possibly, most researches on multiple cropping systems have focused on yields and the resources use efficiency (water, light and nutrients) has been less investigated. in addition, optimal use of nitrogen is important to attain sustainable agriculture due to its role in wue improvement. the experiment carried out during 2008 growing season as split plot based on rcbd design. the main plots included different nitrogen levels (0, 75, 100 and 125 kg.ha-1), which applied as urea and sub plots were three cropping systems consist of sole cropping of pumpkin (cucurbita pepo l. var. styriac) seed and intercropped with four rows of lentil (lens esculenta moench.) and or chickpea (cicer arieinum l.). the results showed that wue and evapo-transpiration efficiency of medicinal pumpkin was affected by n application significantly. however no differences were observed between cropping systems with regard to total water use, wue and evapo-transpiration efficiency. intercropping has no significant effect on total water use, therefore, medicinal pumpkin/ chickpea- lentil intercropping systems can be recommended without any concern in terms of increasing of water consumption.