Salicylic acid and thiourea ameliorated adverse effects of salinity and drought-induced changes in physiological traits and yield of wheat

Scarcity and quality of irrigation water restrict sustainability of wheat production in arid and semi-arid regions. Deficit saline irrigation up to 65% of full water requirement can reduce the salt load along with water saving. Plant bioregulators (PBRs) are phytohormones that regulate physiological and biochemical reactions in plants and respond to variety of abiotic stresses. But the field scale quantification of mitigating effect of PBRs application at representative sites having multiple stresses (deficit water and salinity) is rare. Present study was carried out for two successive years from 2016-17 to 2017-18 at ICAR-Central Soil Salinity Institute (ICAR-CSSRI) research farm, Nain, Panipat, Haryana, India, to assess the effectiveness of two PBRs, i.e., salicylic acid (SA) and thiourea (TU). In a triple replicated, split-split design experiment, two PBRs applied as seed priming and foliar sprays at booting and milking (critical stages) stages in alleviation of adverse effects of deficit (60, 80 and 100% of crop evapo-transpiration) and saline (ECiw; 2, 4, 8, 12 dS m(-1)) irrigation on wheat variety KRL 210. The grain yield reduction under 8 and 12 dS m(-1) were 7.68 and 32.93%, respectively. Higher irrigation amount using highest salinity water (100% ETc + 12 dS m(-1)) caused maximum reduction in grain yield. Application of SA and TU increased grain yield by 12.90 and 17.36%, respectively. Water and salinity (& GE; 8 dS m(-1)) adversely affected the spikes and grains number (m(-2)), relative water content (RWC), proline, membrane injury (MI), Fv/Fm, chlorophyll content (Chl) and Na/K ratio. Positive response of PBRs increased with increasing intensity of both the stresses. At mild salinity (4 dS m(-1)), SA performed better than TU, but at severe salinity (12 dS m(-1)), TU performed better than SA. The study concluded that the application of SA and TU effectively ameliorated the salinity and drought stress in wheat.