Better Osmotic Adjustment Mediates Salt and PEG Stress Tolerance in Primed Plants of Contrasting Cultivars of Sugarcane

Priming improves germination, vigour and performance under environmental conditions in seed crops; however, priming mediated stress tolerance is not much understood in vegetatively propagated crop plants. Here we report growth and physiological characteristics in salt primed sugarcane plants upon 15 days exposure to salt (NaCl, 150 mM) or iso-osmotic (-0.7 MPa) polyethylene glycol-PEG 8000 (20 % w/v) stress in contrasting cultivars: salt sensitive CoC 671 and tolerant Co 62175. Priming led to variable growth, osmolyte accumulation and antioxidant capacity. Priming could not further improve tolerance to salt or PEG stress in salt tolerant cultivar, while the primed plants of the salt sensitive cultivar showed improved tolerance. Priming led to improved shoot growth, reduced leaf senescence and better osmotic adjustment through accumulation of glycine betaine and dissolved ionic solutes in sensitive cultivar upon exposure to salt or PEG stress. The results suggest that osmotic adjustment plays an important role in increasing the stress tolerance of primed sugarcane plants.