Movimento de estômatos em café sob condições naturais

Resumo

By using the ‘infiltration series devised by Alvim and Havis, stomatal movement of coffee trees (Coffea arabica L., var. Bourbon) grow in the open and under shade was determined under natural conditions. The following conclusions were drawn:

1. During the dry season, stomates were almost completely closed during the day in both shaded and unshaded coffee. In both, the aperture was slightly wider during early morning hours. This effect is no doubt due to a limited soil moisture supply.

2. During the rainy season, the stomates were fully open on cloudy days. During sunny days, they began to close at about 10 A.M., attaining relatively low apertures by late afternoon. Such effects are attributed to the water balance of leaves.

3. The shading apparently brought about a decrease in the estomatal aperture as compared to coffee trees in the open under similar conditions. This effect is not, however, very pronounced. The present data suggest a dominant effect of the wae balance of the leaves on the stomatal movement of cofee.

5. It is emphasized that the present study deals with stomatal behaviour of colfee orchards rather than of indivi- dual leaves.