Experimental study of the types of cavitation by air seeding using light microscopy.
Recently, three types of cavitation: (i) expanding gradually; (ii) expanding-exploding, becoming a long-shaped bubble-lengthening by degrees; (iii) suddenly exploding and fully filling the conduit instantly, were proposed. Directed by this theory, experiments were performed using light microscopy to study the natural drying processes of xylem sections of Platycladus orientalis (L.) Franco. Three different phenomena of gas filling process in conduits were captured by replaying recorded videos. The first phenomenon is that a bubble emerging in a conduit expands and elongates gradually to fill the conduit. The second phenomenon is that a bubble emerging in a conduit expands gradually, and then suddenly becomes long-shaped, and extends continuously. The third phenomenon is that a bubble instantly fully fills a conduit. This paper suggests in these experiments that after losing the bulk water of a section, as the water stress of that section became more severe, the water pressures of different conduits of the section were not necessarily the same, and as time went on, the water pressures decreased constantly. Considering some practical factors, the three phenomena captured in our experiment are explained by our theory.
College of Science, Beijing Forestry University, Beijing 100083, PR China fyshen@bjfu.edu.cn.
Fanyi
F
Shen
College of Science, Beijing Forestry University, Beijing 100083, PR China.
Yanxia
Y
Cheng
College of Science, Beijing Forestry University, Beijing 100083, PR China.
Li
L
Zhang
College of Biology, Beijing Forestry University, Beijing 100083, PR China.
Rongfu
R
Gao
College of Science, Beijing Forestry University, Beijing 100083, PR China.
Xuemeng
X
Shao
D029779:Cupressaceae / Q000502:physiology*; D003890:Desiccation; D008853:Microscopy; D014867:Water / Q000502:physiology*; D052584:Xylem / Q000502:physiology*
D014867:Water
air bubble; explosion; extending; water pressure