Sechium edule (Jacq.) Swartz is a neotropical species that is notable for its diverse uses since ancient times. The commercial success of the chayote has motivated an increase in farming area for its cultivation in atypical agro-climatic areas. This study determined the diurnal pattern of gas exchange, water relationships, and morphological characteristics of the chayote leaf related to the gas exchange process. Observations were performed once a month during the production cycle (four months). It was observed that S. edule has amphistomatous leaves with five types of trichomes. The gas exchange pattern showed partial stomatal closure induced by an increase in leaf temperature, as a consequence, the transpiration and the assimilation rate were also affected. Changes in pH in the leaf xylem sap were related directly to the changes in stomatal conductance. The xylem sap analysis showed that K+ and Ca2+ were the most abundant ions and that they maintained a proportion of 3:1 up to 6:1. It was concluded that under atypical field conditions Sechium edule restricts its physiological processes related to gas exchange and water relations by partial stomatal closure.

....