Comparison of Pressure Chamber and Thermocouple Psychrometer Determinations of Leaf Water Status in Tomato

Abstract

Although the pressure chamber has gained wide acceptance as a convenient method for the measurement of plant water status, the relationship between the pressure observed in the chamber and other parameters of plant water status remains unclear. If one assumes that the spatial arrangement of water in the shoot is the same under pressure as it was in the intact plant, the positive pressure (P) and xylem solute potential (41'.) are acting in the chamber to restore the excised shoot to its original volume. In the case of leaf samples, Boyer (4) proposed that P and 4 , t are related to the original leaf water potential ({L) by equation 1: { L == 4's-P