Seed germination responses to salt stress in wild and cultivated Sicilian cardoon genotypes

Salinity is a widespread stress issue limiting the growth and productivity of cultivated plants. More than 20% of the world's cultivated area is considered saline. Within this frame the identification and selection of genotypes able to germinate under salt stress conditions is necessary for the success of the cultivation in marginal areas of the Mediterranean basin. The study was aimed at evaluating the germination response to salinity stress of a selected line of Cynara cardunculus L. var. altilis DC. (Line R07), highly salt-stress tolerant, obtained in previous activity at ISAFOM (Institute for Agricultural and Forest Systems in the Mediterranean), compared to some populations of C. cardunculus L. var. sylvestris Lam., collected in environments with different soil compositions and climate regime in eastern Sicily. The experiments were conducted using four different electrical conductivity and polyethylene glycol of the water conditions: 0.0 (control); 5.7 dS m-1 (-0.3 MPa); 9.5 dS m-1 (-0.6 MPa) and 17.6 dS m-1 (-0.9 MPa), for each treatment four replica dishes were used with 25 seeds each. The salinity stress was performed adding NaCl solution to the germination medium. Overall, the different water potential conditions showed always a germination percentage higher than 75% for the type of C. cardunculus var. altilis. As regards to the wild populations of C. cardunculus var. sylvestris a severe decrease of germinated seed percentage with the increasing of conductivity was recorded. These genetic materials could be utilized for breeding programs in order to allow their introduction in cultivation system in some areas of the Mediterranean environment subjected to salt stress.