GAS EXCHANGE, GROWTH, YIELD AND BEVERAGE QUALITY OF COFFEA ARABICA CULTIVARS GRAFTED ON TO C. CANEPHORA AND C. CONGENSIS

Abstract

Gas exchange, leaf carbon isotope discrimination, growth, yield and beverage quality were evaluated for two Coffea arabica cultivars (Catuai and Mundo Novo), grafted on to C. canephora and C. congensis progenies growing in open fields. During the years 1994 to 1997, grafting resulted in an average increase in bean yield of 151 and 89% for Catuai and Mundo Novo respectively. As analysed by sensory analyses and by the ratio between the mono-isomers and di-isomers of caffeoylquinic acid, beverage quality of the C. arabica was not altered by grafting. Shoot growth was significantly greater in grafted plants, showing an increase of 52% in total leaf area compared with the non-grafted plants. Under conditions of water excess in the soil there was little difference in the transpiration and stomatal conductance rates between the grafted and non-grafted plants, but the net photosynthesis was higher in grafted plants. With an accentuated water deficit in the soil in the dry period, the grafted plants showed significantly higher transpiration and stomatal conductance rates than the non-grafted plants, and similar values to those of C. canephora. Carbon isotope discrimination was greater in the grafted plants, suggesting greater root hydraulic conductance. The results suggest that the better performance of the grafted plants during the dry period was due to the greater capacity of the root system of C. canephora to provide water to the shoot thereby maintaining greater gas exchange in the leaves and consequently a greater carbon gain.

Impacts of drought and temperature stress on coffee physiology and production: a review

“…There is also circumstantial evidence that stomatal aperture in C. canephora cv. Apoatã, presumably promoted by chemical signals from roots, is less responsive to decreasing soil water availability than in arabica (Fahl et al, 2001). Because robusta coffee evolved in a wetter region than arabica, the requirement for efficient stomatal control of E would thus be less important for robusta than for arabica coffee (DaMatta, 2003).…”

“…Apoatã (Brunini and Angelocci, 1998;Fahl et al, 2001). Although a contentious issue (see Rena and DaMatta, 2002), Apoatã also appears to have a much more developed root system than arabica cultivars (Ramos and Lima, 1980), which would enable it to increase access to soil water and, as a consequence, to maintain a favourable internal water status.…”

Aspects of nitrogen metabolism in coffee plants

“…In fact, most coffee genotypes presently cultivated in Brazil were obtained by genetic breeding under full sunlight and wide spacing, and maintain high stomatal conductance and transpiration rates even under high irradiance-temperature regimes, when water availability is not limiting (Carelli et al, 1999;Fahl et al, 2001). In addition, maximum air temperature in traditional coffee growing regions of Costa Rica and Brazil (ca.…”

Exploring drought tolerance in coffee: a physiological approach with some insights for plant breeding

“…Apoatã (C. canephora var. robusta) by chemical signals from roots is less responsive to decreasing soil water availability than in arabica (Fahl et al, 2001). Robusta thrives in a typical equatorial climate (abundant rainfall distributed over a nine to ten month period and relative humidity approaching saturation), whereas arabica coffee evolved in a region marked by a relative dry season lasting about four to five months together with a relatively lower atmospheric humidity (Willson, 1999).…”