Methodological aspects and experimental conditions in the use of fluorescence as an index of water stress in cut leaves from genus Vitis

Abstract

Fluorescence emission is linked to leaf physiological conditions. In particular water stress modifies emission curves strongly. But fluorescence is also influenced by some factors which usually arise in experimental vine breeding programmes. The present research studies some variables that usually characterize the trials on genus Vitis: rootstocks and graftings.

The time of measurement is very important and the fluorescence variables (absolute value) are not correlated with leaf water content. It needs a standardisation by time. The gross relation between fluorescence (after standardisation) and RWC is significant but it is modified by the rootstock behaviour. The Variable Fluorescence is strongly linked to leaf water content, even though the Maximum rate of Fluorescence Quenching shows a variable correlation with decreasing RWC. The genotype controls that variable better than Variable Fluorescence.