To determine if changes in electrical potentials within woody perennial fruit tree and vine species are associated with different types and intensities of abiotic stress as well as early plant physiological responses.

1.- To measure and relate the existence of changes in electrical potentials (EP) in four fruit crop species (economically important to Chile) with the degree of water stress and to relate changes EP to incipient plant stress responses to soil water deficits. 2.- To measure and relate the existence of changes in EP in four fruit crop species (economically important to Chile) to degrees of salinity and osmotic stress and to relate changes in EP to incipient plant stress responses to salinity and osmotic stress. 3.- To measure and relate the existence of changes in EP in four fruit crop species (economically important to Chile) to cold stress and to relate changes in EP to incipient plant stress responses to low temperatures. 4.- To measure and relate the existence of changes in EP in four fruit crop species (economically important to Chile) to heat stress, and to relate changes in EP incipient plant stress to high temperatures. 5.- To measure and relate the existence of changes in EP in four fruit crop species (economically important to Chile) with varying of soil oxygen contents and to relate changes in EP to incipient plant stress responses to oxygen deficits in the root zone.