Three types of cavitation caused by air seeding

Abstract

There are different opinions of the dynamics of an air bubble entering a xylem conduit. In this paper, we present a thorough mechanical analysis and conclude that there are three types of cavitation caused by air seeding. After an air seed enters a conduit at high xylem pressure P'(1), along with the drop of the water potential, it will expand gradually to a long-shaped bubble and extend continually. This is the first type of air seeding, or the type of expanding gradually. When the xylem pressure is moderate, right after an air seed enters a conduit, it will expand first. Then, as soon as the pressure reaches a threshold the bubble will blow up to form a bubble in long shape, accompanied by acoustic (or ultra-acoustic) emission. It will extend further as xylem pressure decreases continually. This is the second type of air seeding, or the type of expanding-exploding, becoming a long-shaped bubble-lengthening by degrees. In the range of P'(1) ≤ - 3P(o) (P(o) is atmospheric pressure), soon after an air seed is sucked into a conduit it will explode immediately and the conduit will be full of the gas of the bubble instantly. This is the third type of air seeding, or the type of sudden exploding and filling conduit instantly. The third type is the frequent event in daily life of plant.

Catastrophic hydraulic failure and tipping points in plants

“…These three regimes are similar to those derived from thermodynamic considerations discussed elsewhere (Konrad & Roth‐Nebelsick, 2005; Shen et al, 2012). As shown in Figure 2, the point $${n}_{\max }({R}_{m})$$ represents a saddle node formed by the intersection of the stable and unstable branches of the equilibrium $${n}_{a}(R)$$ curve (Figure 2).…”

Evidence for Air-Seeding: Watching the Formation of Embolism in Conifer Xylem

“…were detected, when pit aspiration, air-seeding and a fast movement of many air-water menisci was observed. This pattern also corresponds to the three phases of air-seeding postulated by Fanyi et al (2012) with acoustic emissions only on rapid expansion at low ψ. On further dehydration, ultrasonic activity ceased because all tracheids were embolised.…”

Hydraulic Strategy of Cactus Root–Stem Junction for Effective Water Transport

“…If the relation between the conduit radius and embolism spreading are only considered in a hydrodynamic viewpoint, then the conduit of small radius will be more vulnerable to make the seeded air bubble to induce cavitation inside the conduit. When the seeded bubble increases and reaches the conduit radius, it starts to induce cavitation (Shen et al, 2012 ). Nonetheless, this hydrodynamic concept does not work in real xylem vessels where large-scale conduits are highly vulnerable to embolization.…”