Potencial de utilização de cultivares F2 de Coffea arabica L.

Abstract

In the species Coffea arabica L., the cultivars developed are lines propagated by seeds. The development of a new lineage is a long process, requiring 25 to 30 years of research,

resources and dedication from researchers. In addition to time, successive generations of self- fertilization reduce hybrid vigor or heterosis, impacting the productivity of the lineage.

Therefore, new strategies must be developed aiming to reduce time and explore heterosis in Arabica coffee through seminal propagation. Thus, three studies were carried out to evaluate the potential of F2 populations of C. arabica for resistance to coffee orange rust, root-knot nematodes, vegetative development and productive. In the first work, the objective was to evaluate the level of resistance to rust in plants in the F2 generation. Additionally, we sought to verify the effect of rust on the photochemical efficiency and enzymatic activity of plants. F2 populations of Arabica coffee may present complete and incomplete resistance to rust, making their use as commercial cultivars viable. Coffee rust reduces the efficiency of photosynthetic parameters in plants with incomplete resistance. Infection of the fungus Hemileia vastatrix increases the expression of SOD and CAT enzymes in C. arabica L plants. In the second work, the objective was to evaluate the resistance of F2 populations of Arabica coffee to the nematodes Meloidogyne exigua and Meloidogyne paranaensis. F2 populations of Arabica coffee may have 100% plants resistant to the nematode Meloidogyne exigua. In relation to the nematode Meloidogyne paranaensis, the percentage of resistant plants obtained in the F2 generation ranged from 66,7% to 70%. In the third work, the objective was to verify the productive potential and heterosis of the F1 hybrids that gave rise to the F2 populations studied and to evaluate the performance and preservation of heterosis of Arabica coffee plants in the F2 generation. The F1 hybrids EPAMIG 36, EPAMIG 02, EPAMIG 44 and EPAMIG 43 presented the highest accumulated productivity in the three harvests and heterosis varied from 17.2% to 95.5%. The F2 populations showed satisfactory initial development. Given the results obtained, it is concluded that it is possible to obtain F2 populations of C. arabica resistant to rust and root-knot nematodes and with good initial development.