Seed Priming Modulates Physiological and Agronomic Attributes of Maize (Zea mays L.) under Induced Polyethylene Glycol Osmotic Stress

Drought and osmotic stresses are major threats to agriculturalcrops as they affect plants during their life cycle. The seeds aremore susceptible to these stresses during germination and establishmentof seedlings. To cope with these abiotic stresses, various seed primingtechniques have broadly been used. The present study aimed to assessseed priming techniques under osmotic stress. Osmo-priming with chitosan(1 and 2%), hydro-priming with distilled water, and thermo-primingat 4 degrees C were used on the physiology and agronomy of Zea mays L. under polyethylene glycol (PEG-4000)-inducedosmotic stress (-0.2 and -0.4 MPa). The vegetative response,osmolyte content, and antioxidant enzymes of two varieties (Pearland Sargodha 2002 White) were studied under induced osmotic stress.The results showed that seed germination and seedling growth wereinhibited under osmotic stress and germination percentage, and theseed vigor index was enhanced in both varieties of Z. mays L. with chitosan osmo-priming. Osmo-primingwith chitosan and hydro-priming with distilled water modulated thelevel of photosynthetic pigments and proline, which were reduced underinduced osmotic stress; moreover, the activities of antioxidant enzymeswere improved significantly. In conclusion, osmotic stress adverselyaffects the growth and physiological attributes; on the contrary,seed priming ameliorated the stress tolerance resistance of Z. mays L. cultivars to PEG-induced osmotic stressby activating the natural antioxidation enzymatic system and accumulatingosmolytes.