Effects of Drought and Salinity,etc.on Root Pressure ofDracaena sanderiana

Abstract

AbstractAimRoot pressure plays a crucial role in maintaining tissue hydration and ensuring the functionality of the plant’s hydraulic system while facilitating cellular and tissue growth. The study focuses on investigating the impact of drought, salinity,etc.on root pressure ofDracaena sanderiana.MethodsPressure sensors (PX26-100GV) were used to measure the diurnal variations in root pressure of soil-cultured and hydroponicD. sanderianawith heights ranging from 60 to 80 cm. The study also examined various influencing factors such as drought stress, salinity stress, temperatures, mineral concentration, change in leaves and roots that affect root pressure. This approach provides valuable insights into the role of root pressure in mediating water upward movement in xylem.Essential findingsThe research showed: (1) Both soil-cultured and hydroponicD. sanderianaexhibited positive root pressure throughout the day, demonstrating apparent diurnal pattern of high pressures at the day and low pressures at night. The maximum root pressure measured in the experiments was 96 kPa; (2) For soil-culturedD. sanderiana, root pressure decreased under drought and salinization (NaCl), while the diurnal rhythm remained unchanged; (3) For hydroponicD. sanderiana, under simulated drought (PEG 6000) and salt stress (NaCl), the rate of decrease in root pressure accelerated with increasing concentrations of PEG 6000 and NaCl, displaying diurnal rhythm at low concentrations but losing this pattern at high concentrations; (4) Under room temperature, root pressure of hydroponicD. sanderianadecreased with lower water temperature and increased with higher temperatures, but did not increase at 40℃; low concentrations of nitrate (KNO3) generally increased root pressure, however, root pressure decreased when con-centration reached 4 g·L-1, and the diurnal rhythm remained unaffected; (5) For hydroponicD. sanderiana, the presence of leaves on the stem below the root pressure measurement point resulted in significantly lower root pressure compared to plants without leaves on the stem, while still maintaining a regular diurnal rhythm. Removal of all root hairs and the entire root system led to a rapid decline in root pressure to negative values, followed by a slow recovery to around 0 kPa. In conclusion, relative to its height, the root pressure ofD. sanderianais sufficient to transport water required for transpiration to the top of the plant, effectively countering the impact and function of transpirational pull. Moreover, root pressure shows a stable diurnal rhythm of higher values during the day and lower at night. Environmental factors such as drought, salinity stress, temperatures, mineral con-centration, and changes in leaves and roots significantly affect root pressure.