Physiological effects of seed priming on barley cultivated under phosphorus deficiency conditions

Low phosphorus (P) availability is an environmental factor that limits plant growth and productivity in many parts of the world notably in Mediterranean regions where calcareous soils largely prevail. To improve the yield of crops in soils deficient in this element, various research strategies are adopted, including the priming of seeds. This study aims to explore the effects of seed priming with three agents: NaCl (250 mM), PEG (21%), and KH2PO4 (100 mM) on barley seed germination and P deficiency tolerance of the resulting plants. Results showed that three seed-priming agents have accelerated the rate of germination and improved significantly coleoptiles and ridicule length of barley seedlings. Furthermore, KH2PO4 and PEG are the most effective in mitigating the effect of P deficiency on whole plant and root biomasses. However, no significant changes in photosynthetic activity, leaf chlorophyll content and water relations were observed between plants derived from primed and unprimed seeds. Interestingly, the highest root-to-shoot dry weight ratio (DW),leaf anthocyanin and P contents were observed in plants derived from seeds primed by PEG and KH2PO4. In conclusion, seed priming of barley stimulates germination and growth of barley plants cultivated under P shortage conditions. The enhanced biomass observed under P limiting conditions in plants derived from seeds primed by KH2PO4 and PEG is likely explained by the increase in shoot P and anthocyanin contents and notably the enhancement of root biomass and root/shoot DW ratio.