• Siddulu Nari
• Ramakrishna Bellamkonda
• Sangineni Anuradha
• Sadhu Seeta Ram Rao

The main objective of the present research was to investigate the effect of chromium Cr(VI) toxicity on the gas exchange parameters and photochemistry of photosystem II (PSII) and its amelioration by foliar application of brassinosteroids (BRs) (24-epibrassinolide (EBL) and 28-homobrassinolide (HBL)) in sunflower plants. Plant height, root length, chlorophyll a, b, and carotenoids, as well as gas exchange indices such as net photosynthetic rate (Pn), transpiration rate (E), internal CO2 concentration (Ci), and stomatal conductance (Gs), were all significantly reduced in sunflower plants subjected to 2 mM Cr(VI). However, follow-up treatment with EBL and HBL increased the plant growth, photosynthetic pigments and gas exchanges in stressed and stress free plants. Further, excess Cr(VI) levels caused the photoinhibition as demonstrated by lower maximal photochemical efficiency of PSII (Fv/Fm), quantum efficiency of PSII (ϕPSII) and photochemical quenching (qP). Exogenous EBL and HBL application protected the PSII and improved the Fv/Fm, ΦPSII and qP in sunflower plants resulting in improved plant growth. It is concluded that BRs effectively reduced the Cr(VI) toxicity, and its application may be recommended for crops suffering from Cr (VI) toxicity to get better growth and yield.

Chromium, Brassinosteroids, 24-epibrassinolide, 28-homobrassinolide, sunflower, Photosynthetic pigments, Cr toxicity,

"FOLIAR APPLICATION OF BRASSINOSTEROIDS IMPROVED THE PHOTOSYNTHETIC PERFORMANCE OF SUNFLOWER UNDER CHROMIUM STRESS", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.6, Issue 3, page no.360-372, March-2019, Available :http://www.jetir.org/papers/JETIR1903M46.pdf

"FOLIAR APPLICATION OF BRASSINOSTEROIDS IMPROVED THE PHOTOSYNTHETIC PERFORMANCE OF SUNFLOWER UNDER CHROMIUM STRESS", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.6, Issue 3, page no. pp360-372, March-2019, Available at : http://www.jetir.org/papers/JETIR1903M46.pdf