K2SiO3 promotes the growth and improves drought resistance of Haloxylon ammodendron

In the study, the vermiculite was used as substrate and the modified 1/2 Hoagland nutrient solution containing K2SiO3 (KCl as control) was irrigated to study the physiological effects of silicon (Si) on the growth and drought resistance of the succulent xerophyte Haloxylon ammodendron. Results showed that the low concentration of K2SiO3 (KCl as control) stimulated the growth and 15 mmol·L-1 K2SiO3 (30 mmol·L-1 KCl as control) was the optimum concentration, while ≥50 mmol·L-1 K2SiO3 significantly inhibited the growth of H. ammodendron. Compared with the control and 30 mmol·L-1 KCl, 15 mmol·L-1 K2SiO3 significantly increased plant height by 20.2% and 11.4%, branching numbers by 41.4% and 21.6%, fresh weight by 39.1% and 14.5%, and water content by 35.2% and 13.8%, respectively(P0.05). Under different osmotic stress (-0.5,-1.0 and -1.5 MPa), 15 mmol·L-1 K2SiO3 (30 mmol·L-1 KCl as control) significantly improved the drought resistance and alleviated the harmful effects of H. ammodendron by decreasing the content of MDA and relative conductivity in assimilating shoots. Compared with the control and 30 mmol·L-1 KCl, 15mmol·L-1 K2SiO3 significantly increased plant height by 24.7% and 10.1%, 26.4% and 13.8%, 24.2% and 12.9%, respectively, and fresh weight by 43.6% and 15.7%, 52.7% and 15.0%, 59.3% and 20.1%, respectively, while the MDA concentration in assimilating shoots significantly decreased by 26% and 12%, 32.8% and 17.2%, 31.3% and 17.2%, respectively, and relative conductivity by 26.7% and 13.3%, 41.2% and 23.5%, 47.5% and 25% in the mild (-0.5 MPa), moderate (-1.0 MPa) and severe osmotic stress (-1.5 MPa), respectively(P0.05). The results showed that a certain amount of K2SiO3 (KCl as control) could promote growth and improve the drought resistance of H. ammodendron by decreasing the relative conductivity and MDA content in assimilating shoots.