EFFECTS OF GENIPOSIDE ON THE REGULATION MECHANISMS OF PHOTOSYNTHETIC PHYSIOLOGY, ROOT OSMOSIS AND HORMONE LEVELS IN MAIZE UNDER SALINE- ALKALI STRESS

The aim of the study was to monitor the effects of exogenous geniposide (GD) on maize (Zea mays L.) and explore the mechanisms through which it mitigates saline-alkali stress to provide a theoretical basis for revealing the growth physiology and chemical regulation processes in maize The control (CK) received nutrient solution culture while the group under saline-alkali stress(SAS) received 150mmol L-1 saline-alkali solution (molar concentration ratio NaCl:Na2SO4:NaHCO3:Na2CO3 =1:9:9:1). 'Jilong2' (saline-alkali tolerant) and 'Xinxuan58' (saline-alkali sensitive) were chosen as experimental materials and were cultivated with hydroponic method. Maize received the saline-alkali solution 12 hours after GD treatment and saline-alkali solution was administered 3 times, every 12 hours. The GD and saline-alkali solution group constituted the S+G treatment which promoted maize and a significant increase was observed in fresh and dry weights, plant height and photosynthetic enzymes in the leaf along with a significant decrease in the root to shoot ratio compared with saline-alkali treatment The indoleacetic acid (IAA), zeatin-riboside (ZR), gibberellin (GA), superoxide radical (O-2(-)) generation rate, malonaldehy (MDA) and hydrogen peroxide (H2O2) levels in roots were significantly lower than in the S+G treatment under saline-alkali stress, while the level of abscisic acid (ABA) and the activity of antioxidative enzymes increased.