Besides the possible stress imposed by low relative air humidity, it seems that there is some signal emission from the roots, which would also be sensitized by low soil humidity. Plants grown with the root system divided in two parts and in separate containers (one with good water supply and another one with low water supply) presented water potential in the leaves similar to plants with irrigation in both containers (Crisosto et al. 1992). Nonetheless, flower opening was observed in the plants in which one of the roots sides had suffered water limitations.