Study of water deficit conditions and beneficial microbes on the oil quality and agronomic traits of canola (Brassica napus L.)

Water deficit stress is one of the major limiting factors that adversely affect plant growth and yield production. Some rhizosphere bacteria are known to promote plant growth in such stressful conditions. To study the response of quantifying canola growth, yield and yield components, to root colonization by two species of mycorrhizal fungi, a two-year field experiment was conducted at the research farm of Zanjan University. The main plot conditions were irrigation at 85% (S-1), 70% (S-2) and 55% (S-3) of field capacity which were defined as no stress, mild and severe stress. The subplot treatments included three levels of mycorrhizal inoculation: non inoculation (control), G. mosseae and G. intraradices. The results showed that regardless of water deficit stress, colonized plants produced more biomass, seed and oil yield than non inoculated plants. Water deficit stress reduced the RWC and oil percentage of the seeds, although mycorrhizal improved these traits. Water deficit strikingly decreased the linoleic acid content in the seeds in contrast with increased stearic, oleic, arachidic and linolenic acids in the canola seeds. The presence of bacteria increased the seed oil percentage, oleic and linoleic contents. However, it decreased arachidic, particularly when the plants were subjected to water deficit stress.