Response of sunflower (Helianthus annuus L.) to arsenic stress: Accumulation and partitioning in different plant parts

The experiment was performed using two cultivars (FH-331 and FH-385) of sunflower (Helianthus annuus L.) to study the arsenic distribution pattern in different plant tissues. Arsenic was applied at 0, 20, 40, 60, 80 and 100 mg kg(-1) soil in the form of Na2HAsO4.7H(2)O or NaAsO2. Results revealed that increase in rhizospheric arsenic significantly reduced the root depth, shoot height, fresh and dry mass of root as well as shoot, number of leaves per plant and yield parameters, such as, capitulum diameter and achene mass. Arsenic accumulation in the plant tissues increased with increase in soil arsenic level with varied uptake in different plant tissues. Arsenic concentration in different plant tissues were in order of: roots > leaves > shoot > achenes. The maximum concentration of arsenic (87.66 mu g g(-1) dry mass) was found in root tissues of plants receiving 100 and 36.6 mg As kg(-1) soil in the form of NaAsO2 and Na2HAsO4.7H(2)O, respectively. Lower accumulation of arsenic in achenes as compared to all other plant tissues revealed poor translocation of this toxic element to the fruit. We concluded from present study that Arsenic predominantly deposited into the leaves of sunflower rather than the seeds. Our findings may assist the sunflower cultivation program in Arsenic contaminated soil.