GR24 Triggered Variations in Morpho-Physiological Attributes of Sunflower (Helianthus annuus) under Salinity

Sunflower (Helianthus annuus L.) is a palatable oil crop worldwide and its production is threatened by salt stress. Phytohormones are helpful to alleviate the salt stress by regulating the plant metabolism. To evaluate the response of sunflower to salt stress and GR24, a synthetic strigolactone analogue was applied as foliar spray. Replicates of sunflower hybrids (FH-593 and FH-596) were grown in the pots under two levels of salinity (0, and 120 mM NaCl) and four levels of GR24 treatments (0, 3.35, 33.5 and 335 nM). The results showed that salinity inhibited the shoots and roots growth, whereas GR24 upgraded the growth under salinity. Leaf gas exchange attributes, photosynthetic pigments and water relation attributes were declined under salinity and GR24 application partially reversed adverse effects of salinity on gas exchange attributes. GR24 spray did not affect the photosynthetic pigments. Additionally, foliar application of GR24 decreased leaf water potential and turgor potential but raised osmotic potential and relative water contents in response to salt stress. The GR24 level 33.5 nM was most effective in alleviating the harmful impact of salinity Both hybrids showed variable response to overcome salinity stress. (C) 2019 Friends Science Publishers