Physiological aspects and yield in coffee progenies with large beans

Genetic coffee breeding is aimed at increasing yield associated with tolerance or resistance to biotic and abiotic factors, besides providing a better beverage quality and supplying the demand for bigger beans. The efficiency in photosynthetic activity can limit produce and diversify genotypes, mainly under adverse environmental conditions. Consequently, the importance of selection of Coffea arabica L. regarding these characteristics stands out. Therefore, the objective of this paper was to measure the physiological characterization and yield of Coffea arabica L. progenies with large beans “Big Coffee VL”. Twelve productive progenies were selected and classified according to fruit size (“small”, “medium” and “large”), which were: S14, S23, S34, S36, M4, M5, M14, M20, L10, L12, L17 and L31. Net photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E), water use efficiency (WUE), internal carbon (Ci), intercellular CO2 concentration in the mesophyll were evaluated on the current external CO2 concentration (Ci/Ca), besides vapor pressure deficit (VPD), leaf temperature (Tleaf), indirect determination of the relative levels of chlorophylls a, b and total, in addition to bean yield in two crops. The Tocher grouping resulted in the formation of 4 groups, and progenies M4, L10 and S34 remained in isolated groups. Progeny L10 stood out for higher mean values of A, gs and Ci; the opposite behavior was observed in progeny S34. Progeny M4 is noteworthy as the one with the highest yield in the two years considered, in addition to presenting high photosynthetic rate and chlorophyll indexes. It is concluded that the progenies of “Big Coffee VL” show variability for physiological parameters and productivity. Progenies S14, M4 and L10 stood out, and S14 was more efficient in the use of water; M4 was the most productive and L10 stood out in terms of gas exchange. Key words: Chlorophyll; Coffea arabica L.; Gas exchange; Genetic breeding.