关键词: 水培富贵竹, 根压, 蒸腾, 木质部水分运输

Abstract: Abstract Aims Root water absorption and leaf transpiration work together to maintain the dynamic balance of water in plants. The driving forces of water transport in the long distance of plant xylem are transpiration pull and root pressure. It is generally believed that the transpiration pull plays a major role, and the root pressure is small and only works at night or when the transpiration rate is low. Some rattan and herbaceous plants have high root pressure. However, because transpiration pull may also play a role, whether the change of root pressure would directly affect transpiration rate and the response speed and mode of transpiration to the change of root pressure are not clear. Methods In this paper, the effect of low temperature(0℃), high temperature(35℃), salt stress(200 mmol·L-1 NaCl), drought(20% PEG 6000), fibrous root removal and in vitro on root pressure and transpiration of Dracaena sanderiana were studied to explore the feedback of transpiration on root pressure. Important findings (1) The root pressure of D. sanderiana was relatively high. Under non-stress conditions, the root pressure could maintain positive throughout the day and act alone to push water to the top of the stem. The maximum transpiration rate of D. sanderiana was only 0.37 mmol·m?2·s?1, which might be the reason why the root pressure can remain positive throughout the day. (2) After low temperature treatment, both root pressure and transpiration decreased, while increased after high temperature treatment, indicating that the root system was affected by temperature, which in turn affected the production of root pressure, and the changes in root pressure quickly affected transpiration. (3) After salt, drought, fibrous root removal and in vitro treatment, root pressure decreased to a negative value in one day and then gradually recovered to around 0, while transpiration rate decreased slightly after several hours of short time treatment, and decreased to 18-72% of the pre-treatment in the next day, and then decreased to 0 after 4-12 days of long-term treatment, indicating that the transpiration rate and stomatal conductance of D. sanderiana fed back rapidly to the change of root pressure. In conclusion, after the root pressure disappeared, the transpiration pull did not appear to maintain the previous transpiration rate, indicating that the long-distance water transport in the xylem of D. sanderiana has a root pressure driven mechanism, which is different from that of most plants. This study provides theoretical support and guidance for water management in D. sanderiana cultivation.

Key words: hydroponic Dracaena sanderiana, root pressure, transpiration, water transport in xylem