Abstract
Soil alkalinity is a severe threat to crop production globally as it markedly retards plant growth. Different techniques are used to mitigate alkaline stress, but priming techniques are considered the most appropriate. The current study was carried out in complete randomized design (CRD) to evaluate the effect of different priming techniques on maize crop grown under different levels of alkalinity stress. The experiment was comprised of different treatments of alkalinity stress (AS) including, control, 6 dS m(-1) and 12 dS m(-1) and different priming techniques including control, hydro-priming (HP), osmo-priming (OP) with potassium nitrate: KNO3) and redox-priming (RP) with hydrogen peroxide (H2O2). Results indicated that alkalinity stress significantly reduced plant growth and biomass production and induced severe alterations in physiological attributes and antioxidant activities. Soil alkalinity significantly reduced the root and shoot growth and subsequent biomass production by increasing electrolyte leakage (70.60%), hydrogen peroxide (H2O2: 31.65%), malondialdehyde (MDA: 46.23%) and sodium (Nal accumulation (22.76%) and reduction in photosynthetic pigments, relative water contents (RWC), total soluble proteins (TSP) and free amino acids, potassium (K+) accumulation. However, priming treatments significantly alleviated the alkalinity-induced toxic effects and improved plant growth. OP (KNO3) remained the top performing. It appreciably improved plant growth owing to the improved synthesis of photosynthetic pigments, better RWC (16.42%), TSP (138.28%), FAA (178.37%), and K+ accumulation (31.385) and improved antioxidant activities (APX and CAT) by favoring the Na+ exclusion and maintenance of optimum Na+/K+. In conclusion, KNO3 priming is an imperative seed priming practice to improve maize growth and biomass production under alkalinity stress.