Salinization/sodification of soil and physiological dynamics of sunflower irrigated with saline–sodic water amending by potassium and farm yard manure

Sunflower (Helianthus annuus L.) plants were grown with saline–sodic water (SSW) by treating with potassium (K @ 100 and 200 mg K2O kg−1 soil) and farm yard manure (FYM @ 5 and 10% of soil, w/w). Irrigation with untreated SSW caused soil salinization/sodification, leading to an increase in electrical conductivity (EC) of 165% and sodium adsorption ratio (SAR) 100% with the subsequent increase of 736% in shoot Na+, a decrease of 52% in shoot K+ and 94% in shoot K+:Na+ratio compared to canal water. SSW also decreased physiological activities: 31% relative water content (RWC), 34% membrane stability index (MSI), 51% protein, 33% chlorophyll and 58% photosynthetic rate compared to canal water. Integrated application of K and FYM, at higher level, decreased soil EC by 54% and SAR 43%, and shoot Na+ 57% with a corresponding improvement in soil organic matter 166%, shoot K+ 360%, shoot K+:Na+ratio 987%, RWC 34%, MSI 37%, protein 60%, photosynthetic rate 102%, superoxide dismutase 92%, peroxidase 78% and catalase 52% compared to SSW without K and/or FYM. In conclusion, exogenous application of K and FYM could be a promising approach to use brackish water in agriculture on a sustainable basis