Biology 3 (2016 9) 291-303 ~ ~ ~ УДК 633.351 Zeolite Use Effi ciency Variation under Water Defi cit Stress in Grass Pea and Lentil Alireza Pirzad* and Sevil Mohammadzadeh Urmia University Urmia, Iran Received 27.01.2016, received in revised form 24.02.2016, accepted 21.06.2016 To evaluate the effect of different application rates of zeolites under drought stress conditions on the protein and biomass production, and zeolite use effi ciency in grass pea (Lathyrus sativus L.) and lentil (Lens culinaris L.), two-way ANOVA based on randomized complete block design was conducted at Research Farm of Urmia University in 2012. <...> Two levels of irrigation (irrigation at fi eld capacity (FC) and 50 % FC) and four levels of zeolites (0, 10, 20 and 30 tons/ha) were applied. <...> Results of ANOVA showed the signifi cant effect of zeolite application on protein yield, protein harvest index, and zeolite use effi ciency for protein and biomass production and signifi cant effect of irrigation regime on protein yield, protein harvest index and zeolite use effi ciency for grass pea protein production. <...> There were signifi cant effects of zeolite application on the biomass, protein yield, and protein harvest index, and signifi cant effects of irrigation regime on protein yield and protein harvest index of lentil. <...> However signifi cant interaction effect between zeolite and irrigation on zeolite use effi ciency for protein and biomass production in lentil was obtained. <...> The results indicated that water defi cit stress signifi cantly decreased these traits, whereas the application of zeolite compensated the negative effect of the drought stress. <...> Zeolite use effi ciency for grass pea and lentil biomass and protein production decreased in high rates of mineral application (30 tons/ha). <...> The highest protein yield (307.12 kg/ha) and protein harvest index (14.2 %) of grass pea, and protein yield (222.59 kg/ha), biological yield (2587.6 kg/ha), and protein harvest index (8.6 %) of lentil were obtained when 30 tons/ha of zeolite were applied. <...> All rights reserved * Corresponding author E-mail address: a.pirzad@urmia.ac.ir <...>