Hypoxia stress in the root-zone is thought be a major determinant in the adverse effect of O_2 deficiency in hydroponic culture and root-cushion formation in substrate culture on plant species. Now hypoxia stress has become a limited factor of soilless culture application to large area production. Therefore, improving the hypoxia tolerance of plants plays a vital role in soilless culture. As a major element necessary for plant growth and a second messenger of coupling extracelluar signal and intracellular p...