The effects of salinity stress levels on quantity and quality traits of different cultivars of canola under application of vermicompost

There is an increasing pressure to apply low quality brackish waters for plant irrigation in the arid and semi- arid areas of the world. Consequently, there is a demand to identify the salt tolerant of conventional crops and varieties. Vermicompost usefulness has been reported in reducing the harmful effects of salinity on some plants.
In order to investigate the effects of four salinity levels (including 1.15, 4, 7 and 10 dS.m-1) on quantity and quality traits of four cultivars of canola (Hyola 4815, 308 and 401 and RGS 003) under application of 10 Ton.ha-1 vermicompost, an experiment was conducted as factorial based on randomized complete block design with 3 replications. Pot experiment was conducted in a semi- controlled environment. In order to avoid toxic effects of some ions, different levels of salinity were prepared of the composition of different salts as equal weight ratio.
The results showed that cultivar significantly affected the seed yield, biological yield, harvest index, oil yield, seed water use efficiency and oil water use efficiency. Means comparison test indicated that Hyola 401 cultivar had the highest value in whole traits, except in harvest index, although this primacy was not significant in some traits. In contrast, RGS 003 cultivar had the lowest value of seed yield, harvest index and seed water use efficiency. In comparing with RGS 003 cultivar, Hyola 401 has plus 23% seed yield and seed water use efficiency. Also, the results showed that the effect of salinity on seed yield, biological yield and seed water use efficiency was significant. On the base of means comparison test, the lowest value of seed yield, biological yield and seed water use efficiency have been observed in control salinity treatment (1.15 dS.m-1). Highest value of those traits observed in irrigation water salinity 7 dS.m-1 and more increasing of the salinity had an adverse effect. Interactions of salinity and cultivar had no effects on considered traits.
It seems that increasing in seed yield, biological yield and seed water use efficiency in salinity level of 7 dS.m-1is due to the increasing absorption of nutrients from the soil, less leaching of nutrients from the soil because of reduced water solubility and stimulates the plant to cope with the stress led to an increase in those attributes. Also, application of vermicompost led to increasing salinity threshold of canola cultivars because it improves the soil physical and chemical condition.