Study the changes of some physiological properties of rapeseed (Brassica napus L.) under different irrigation levels

In this study the response of 9 rapeseed genotypes were evaluated at the seedling stage using different irrigation levels (50, 70 and 100% FC). A factorial experiment based on RCBD was conducted in the research greenhouses of Urmia University with four replications during summer of 2013. Some physiological traits such as relative water content, stomatal conductance, transpiration, photosynthesis, water use efficiency, shoot fresh and dry weight; root dry weight and the amount of soluble and insoluble sugars were evaluated. The results of this study showed that with decreasing irrigation levels, relative water content, stomatal conductance, transpiration, photosynthesis, water use efficiency, shoot fresh and dry weight, root dry weight and insoluble sugars decreased, however the amount of leaf temperature, SPAD number and soluble sugars increased. The highest rate of net photosynthesis was observed in Zarfam and Licord genotypes at 100% of field capacity. The maximum decreasing in net photosynthesis was observed in Licord genotype by increasing water stress level (50% field capacity). Under severe drought stress, maximum shoot fresh and dry weight was observed in Zarfam genotype while it was lowest in the Zafar and Licord genotypes. Using cluster analysis in 50% FC, the genotypes were located in two groups of semi resistant (Zarfam, Karaj 2, Okapi and Karaj 3) and sensitive (Sarigol, Opera, Zafar, SLM, and Licord).