Water relations of coffee leaves (Coffea arabica and C. canephora) in response to drougth
Coffee plants of five Arabica and one Canephora genotypes were raised in containers with 0.02 m3 of soil, under a clear plastic shelter. When they were 18 months old, irrigation was withheld until the first signs of wilting appeared. This occurred four to five days after withholding irrigation, when the pre-dawn water potential of young fully expanded leaves of the plagiotropic branches was about -2.4 MPa. Control plants remained under daily irrigation. The pressure-volume technique was used to estimate volume averaged water relations properties of sample leaves. The turgor loss point was approximately - 1.6 MPa for control plants and -2.0 MPa for stressed plants, an osmotic adjustment of approximately 22 per cent. The Canephora genotype showed a slightly higher adjustment. The relative water content at the turgor loss point remained at approximately 93 per cent. irrespective of genotype or treatment. The maximum bulk modulus of elasticity did not change significantly with water deficit, remaining at about 24 MPa, except for a slight increase in the Canephora genotype. The specific leaf area of the Arabica genotypes decreased about 20 per cent, as compared with a 10 per cent decrease for the Canephora genotype.
| Main Authors: | , , , |
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| Format: | biblioteca |
| Published: |
1993
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| Subjects: | COFFEA ARABICA, COFFEA CANEPHORA, RELACIONES PLANTA AGUA, ESTRES DE SEQUIA, GENOTIPOS, MARCHITEZ, TURGENCIA, |
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