Gholamreza Zamani is working as an academic staff (Associate professor) at Unitversity of Birjand, Iran.
Salinity is one of the most important abiotic stresses and a serious constrain for crop production. Two oilseed amphidiploids Brassica species (canola) including rapeseed/canola (Brassica napus L.) and Indian mustard (B. juncea L.) which have common parent (Brassica rapa L.), are rather salt tolerant so can be used to grow on saline soils and soils affected by saline irrigation.
An experiment was conducted as factorial based on randomized complete block design with three replications in the Research Greenhouse of agriculture faculty, University of Birjand, Iran, in 2015. The first factor consisted of four salinity levels including 1.9 (Hoagland solution as control), 5, 10 and 15 dS/m (NaCl in Hoagland solution) and the second one was genotype consisting of two spring canola cultivars (Hyola401 and RGS003) and Indian mustard landrace. The medium was sand culture in pots. At three stages after starting salinity stress (approximately, stem elongation, flowering and filling pod stages) sampling was done from each treatment to determine photosynthetic pigments including chlorophyll a (CHLa), chlorophyll b (CHLb), total chlorophyll (CHLt), carotenoids (CAR), relative water content (RWC), membrane electrolyte leakage and proline. Data analysis and statistical calculations were done using SPSS and EXCEL software.
Result showed that at second and third stages of sampling, salinity induced significant decrease in CHLa, CHLb, CHLt and CAR but any decline trend didn’t observe in these characteristics at stem elongation stage. With increasing the period of salinity stress, Indian mustard was impressed more than canola cultivars and had the least of mention traits at flowering and podding stages. Results showed membrane electrolyte leakage increased significantly by rising irrigation salinity up to 15 dS/m and the most of it observed at this level. Traits mean comparison illustrated Indian mustard had the highest amount of membrane electrolyte leakage at all stages that the amount of this trait in this genotype at flowering and stem elongation was 50 and 59.2 percent, respectively less than final sampling stage. Increased salinity level, resulted in a downward turn in RWC of canola cultivars that this trend was significant at second and third stages of sampling. Indian mustard had the highest amount of RWC at salinity level of 15dS/m at all stages. Also an upward trend was observed in proline in all genotypes at all stages by rising irrigation salinity. The highest proline in all genotypes was related to the highest salinity level relative to control and increase of this trait was more significant at flowering and podding stages in comparison to stem elongation stage. The least of proline at all stages related to Hyola401. The highest amount of proline at stem elongation and two other stages was related to Indian mustard and RGS003, respectively.
Photosynthetic pigments and RWC of All genotypes at first phenological stage were not affected significantly by salinity but by increasing duration of salt stress significant declines were appeared. There were not significant differences in traits of proline and membrane electrolyte leakage between genotypes at all times of sampling at control level related to salinity levels.