Water relations' aspects of Theobroma cacao L. clones. In: Agrotrópica v. 14 p. 35-44, 2002.

Abstract

The cacao region of South Bahia, responsible for most of the Brazilian cacao production, has extensive areas of shallow soils in which drought spells occur. These conditions contribute to a reduction in water availability that, in some cases, causes plant death. Information on water relations of cacao clones is still incomplete, therefore, this work was planned to study water relations parameters, estimated through pressure-volume curves, to establish relationships with physiological and drought resistance parameters. Eight cacao clones (SIAL-70, TSH-516, SPA-5, CC-10, CEPEC-519; CEPEC-84; EET-376 and SGU-54), grafted onto five month-old seedlings of Cacau Comum were grown in soil under greenhouse conditions for 30 months. Most of them, when submitted to dehydration showed drought resistance via osmotic adjustment. The adjustment was associated to potassium and phosphorus accumulation in the leaf. Interclonal differences in osmotic adjustment were found only when the dehydration was imposed rapidly. The clones SPA-5, SIAL-70 and TSH-516 showed a wider osmotic adjustment mainly due to an increase of osmotic pressures at full saturation and at incipient plasmolysis. The increase in the module of elasticity caused a wider osmotic adjustment only in SPA-5. The results showed that these three clones could be grown in regions of shallow soils and drought spells when grafted onto Cacau Comum.