Foliar application of salicylic acid with salinity stress on physiological and biochemical attributes of sunflower (Helianthus annuus L.) crop

The potential agricultural lands are falling prey to salinity in the world over including Pakistan. The limited water supply is also becoming a serious problem to feed the humans and livestock production. Therefore, research studies were undertaken to enhance the growth and development of sunflower (Helianthus annuus L.) on saline soils to increase productively of crop. The treatments consisted of (a) two lines of sunflower (Hysun-33 and LG-56-63), (b) two levels of salinity (0, 120 mM (NaCl)) and (c) two levels of salicylic acid (0, 200 mg L-1) and were arranged in a completely randomized design with four replications. The results showed that biological yield was significantly reduced due to imposition of salinity at the rate of 120 mM (NaCl) on both sunflower lines (Hysun -33, LG 56-63). The stem length was also reduced due to decrease in biological yield in response to salinity. However, the exogenous application of salicylic acid at the rate of 200 mg L-1 mitigated the adverse effects of salts and improved the biological yield and stem length under saline and non-saline environments. The quantity of chlorophyll (SPAD) values were impacted negatively in response to salt stress, however, the phenomenon was recovered by foliar spray of salicylic acid. The nutrient concentration of K+, Cl- and Na+ were altered because of presence of excess quantity of NaCl in the substrate. The translocation of K+ ion was reduced substantially, while higher amount of Na+ and Cl- ions were absorbed, thus creating ionic imbalance in the plant system. The foliar spray of salicylic acid (200 mg L-1) enhanced the uptake of K+ from the soil medium. The salicylic acid proved a potential phytoprotectant to mitigate the adverse effects of salinity and thereby improving the physiological and biochemicals attributes, stem length and also enhanced uptake of K+ ion while depressing Na+ and Cl- ions in plant system.