16. Which plant has been used in phytoremediation for uptake of cadmium from contaminated soil?
(1) Helianthus annus                                        (2) Brassica juncea
(3) Silene vulgaris                                            (4) Oscimum basalicum

Option-wise explanation

1. Helianthus annuus (sunflower)

• Sunflower can accumulate Cd and Pb and is being researched as a potential phytoextractor.​

• However, in classical exam context, it is less iconic than Indian mustard for cadmium phytoremediation.

2. Brassica juncea (Indian mustard) – correct

• Indian mustard is one of the most extensively used model plants for phytoremediation of Cd‑contaminated soils because it:

  • grows rapidly and produces high biomass,

  • tolerates and accumulates significant Cd levels in shoots,

  • has been repeatedly validated in pot and field studies for Cd (and other metals) removal.​

• Hence it is the standard textbook example and the correct choice here.

3. Silene vulgaris

• Silene vulgaris shows metal tolerance and can accumulate Zn/Cd in metalliferous sites, often used alongside Thlaspi/Noccaea in research.​

• But it is not as widely deployed operationally as B. juncea and is less emphasized in basic phytoremediation MCQs.

4. Ocimum basilicum (basil)

• Recent work shows basil can take up Cd (including Cd-based quantum dots) and has some phytoremediation potential.​

• Nevertheless, it is primarily known as a culinary/medicinal plant, and its use in cadmium phytoremediation is comparatively new and specialized.

Therefore, the plant most classically used for uptake of cadmium from contaminated soil is Brassica juncea (option 2).