Effects Of Exogenous Sugar On The Attenuation Of Salt Stress And Its Physiological Basis In Maize Seedling

The independent breeding maize (Zea Mays L.) variety Kenyu No.6was used to study theeffects of exogenous glucose (Glc) and sucrose(Suc) on seed germination and seedling growthunder salt stress at150mmol·L-1. The salt resistance mechanism was investigated, and thefollowing findings were revealed:Under normal condition without salt stress, compared with the control, the germinationpercentage and germination index of maize seedlings were increased by pretreatment with0.5mmol·L-1Glc and Suc at the early stage of germination; Under salt stress condition, exogenousGlc and Suc resulted in significant increase of germination percentage, germination index,α-amylase activity, embryo length, radicle length, shoot dry weight and root dry weight of maizeseedlings; Moreover, exogenous Glc and Suc pretreatment resulted in increased level of osmoticregulation substances, antioxidants and antioxidant enzymes activity, and maintained the balanceof Na+/K+. The effects of Suc pretreatment on improving seed germination index and prolinecontent were better than Glc.Under normal condition without salt stress, exogenous Glc and Suc treatment couldsignificantly increase the plant height, maintain Pnvalue; Under salt stress condition, exogenousGlc and Suc showed significant reversal of salt stress in growth and accumulation of dry matterin maize seedlings, and significantly increased osmotic regulation substances content in maizeleaves; Glc and Suc pretreatment also alleviated the decreases of Pn, Gs, Trand Fv/Fm, increasedthe Hill reactivity, relative water content and photosynthetic pigment contents under salt stress;Moreover, Glc and Suc pretreatment significantly decreased the TBARS, H2O2contents andincreased autioxidant enzyme activities, ASA, GSH contents and ASA/DHA、GSH/GSSG ratio,and the G6PDH activity was induced by Glc and Suc pretreatment; In addition, the Glc, Sucpretreatment significantly improved K+content and K+/Na+ratio in different organs of maizeseeding; We also found that sucrose pretreatment enhanced Ca2+-ATPase activity andmaintained the balance of Ca2+contents under salt stress.In adition, under salt stress condition, compared to Glc and Suc, isotonic mannitolpretreatment did not make any changes of the physiological and biochemical indicators whichmeant it was not being able to promote germination and growth of maize seedlings under stress condition.