Climate change, coupled with insufficient and irregular rains, led to a decline
in the productivity of Ivorian cocoa production. The present study aimed to
screen three cocoa (Theobroma cacao L.) genotypes in order to evaluate their
response to water stress at callus and somatic embryos induction and proliferation
stages. Staminode and petal explants of the genotypes C1, C14 and C16
from the collection of National Center of Agronomic Research (CNRA) of
Ivory Coast, were placed on medium DKW (Driver & Kuniyuki Walnut) in
the presence of different concentrations of Polyethylene glycol (PEG) 6000 (0,
25, 50, 75, 100 and 125 g/l). This polymer was used as osmoticum to stimulate
water stress. Data were recorded for callus induction frequency, callus fresh
weight, embryogenic callus percentage and average number of somatic embryos.
The results obtained showed that intensity of callus proliferation decreased
with increasing concentration of PEG 6000. In all genotypes tested,
only the petal explants underwent somatic embryogenesis. The induction rates
and average number of somatic embryos per explant were reduced with the
increase in the concentration of PEG 6000. Among the tested genotypes, C1
produced somatic embryos with all concentrations of PEG 6000 and expressed
highest frequencies of induction (62%) and average number of somatic embryos
per explant (6.22). This genotype would be the most tolerant to water
stress. Somatic embryos obtained with high concentrations of PEG 6000 in
this study provide an important basis for the selection and further production
of water stress-tolerant varieties of cocoa.