The Effect of Soil Moisture, Nitrogen Fertilization and some Meteorological Factors on Stomatal Aperture of Coffea Arabica L.

Stomatal aperture in irrigated and non-irrigated plants of Coffeaarabica L. was studied by measuring the infiltration into theleaf of mixtures of iso-propanol and distilled water. In potexperiments, stomatal aperture proved to be closely relatedto soil moisture content. In the field, the coefficient of thecorrelation between stomatal aperture and soil moisture contentin the 10 ft deep rooted zone was 0.929 (r² = 0.863) in thedry season and 0.773 (r² = 0.598) in a period of intermittentrain. Stomatal aperture was invariably inversely correlatedwith the calculated soil moisture deficits of five irrigationtreatments. Application of nitrogen fertilizer increased stomatalaperture but no explanation can be offered for this effect.Stomatal aperture as measured by this particular method waslinearly correlated with temperature, vapour-pressure deficitand radiation, and also related to the time of day.