HYDRAULIC RELATIONS IN PLANT EXPLANTS OF Coffea canephora (Pierre) ex Froehner

Abstract

The demand for Robusta coffee (Coffea canephora) has increased, for the elaboration of soluble coffee, because it contains 2-3 % more caffeine. Genotypes with higher yield have been identified and their massive reproduction is sought through somatic embryogenesis and by identifying their physiological response to different disinfectants through the determination of the capacity for osmotic adjustment. A study was developed to determine the degree of osmotic adjustment of foliar explants of Robusta coffee in the aseptic in vitro establishment. Foliar explants were used of the following genotypes of C. canephora: INIFAP 95-8, 95-9, 97-10, 97-15, 97-18 and 97-20, disinfected with NaClO (0.1, 0.5,1.0, 1.5, 2.0, 2.5, 3.0 and 4.0 %), and Ca(ClO)₂ (3, 4, 5, 6, 7, 8, 9 and 10 %), as well as the combination of both. The hydric, osmotic potential, turgidity, and concentration of Cl^-, Na⁺ and Ca⁺⁺ ions was determined. The results indicated that the genotypes present different capacity of tolerance to disinfectants alone or combined, and in their response to the accumulation of osmotically active substances, with INIFAP 95-9 and 97-20 standing out, with an osmotic adjustment from accumulation of Cl^-, Na⁺ and Ca⁺⁺ , while when combining NaClO and Ca(ClO)₂, the INIFAP 95-8 genotype showed the osmotic adjustment.