www.scholarsresearchlibrary.com t Available online a Scholars Research Library Annals of Biological Research, 2012, 3 (9):4444-4451 (http://scholarsresearchlibrary.com/archive.html) ISSN 0976-1233 CODEN (USA): ABRNBW 4444 Scholars Research Library Study of Drought Stress and Plant Growth Promoting Rhizobacteria (PGPR) on Yield, Yield Components and Seed Oil Content of Different Cultivars and Species of Brassica Oilseed Rape Pooya Arvin 1 , Javad Vafabakhsh 2 , Daryoush Mazaheri 3 , Ghorban Noormohamadi 1 , Mehdi Azizi 2 1 Department of Agronomy, Science and Research Branch, Islamic Azad University, Tehran, Iran 2 Department of Seed and Plant Improvment , Agriculture and Natural Resources Research Center of Khorasan Razavi. ,Mashhad,Iran 3 Department of Agronomy and Plant breeding, Tehran university, ,Tehran,Iran _____________________________________________________________________________________________ ABSTRACT Rapeseed is a new oilseed crop in Iran and its hectares has been currently expanding. Reproductive growth of the crop is exposed to water stress in many part of the country. In order to evaluation of yield, yield component and seed oil content of Brassica oilseed rape cultivars belong to Brassica napus, Brassica rapa and Brassica juncea species at stress and non stress locations with application of Pseudomonas strains , two experiment ( including stress and non stress fields) were carried out on 2010-2011 growing season at Agriculture and Natural Resources Research Station of Torogh, Mashhad. Experimental design was factorial based on Randomized Competently Block Design (RCBD) . Results showed that drought stress caused to reduction of yield , oil content and yield components. Also the negative forceful effect of water deficit on yield components was regarding pod numbers. Violently final yield decreased( 152.5% ) in stress location. There were considerable difference between stress and non stress locations regarding yield, oil content and all yield components. Except number of lateral branches , significant difference at 1% probability level were found among cultivars in studied characteristics .It was concluded that inoculation treatment had better effects than either no inoculation (control) or co-inoculation but interestingly co-inoculation with Pseudomonas flourescens plus Pseudomonas putida was placed at the lowest rating in comparison with individual inoculation or no inculcation at surveyed traits. Key Words: Rapeseed, drought stress, Pseudomonas strains, Yield, yield components, oil content _____________________________________________________________________________________________ INTRODUCTION Iran is situated in semi-arid region and water shortage leads to emerge lots of problem in order to supply of drinking water and water requirements for crop production [1]. In order to UN report , damage of drought in Iran was exceeded to3.5 billion US$ so more than 1 million head of livestock and 3 million tons of wheat and barley were lost due to severe water crisis in year of 2000[2]. Three main mechanisms reduce crop yield by water stress: (i) reduced canopy absorption of photosynthetically active radiation, (ii) lessened radiation-use efficiency and (iii) reduced harvest index .The reproducibility of drought stress treatments is very cumbersome, which significantly impedes research on plant drought tolerance[3].Yield and drought resistance are controlled at separate genetic loci such breeding involves the identification and transfer of physiological traits responsible for drought resistance to high-yielding and agronomically acceptable cultivars[4] .