Preconditioning in vitro of sugarcane (Saccharum spp.) seedlings to salt stress tolerance

The capacity of adaptation to the salinity of seedlings of sugarcane variety RB98710 after priming in vitro with sodium chloride (NaCl) was evaluated. The experiment took place in the period May to October 2013. Plants were micropropagated in temporary immersion bioreactor with priming treatments characterized by the addition of 25 mM NaCl, for 0, 12, 24 and 36 hours. Over periods of priming, the plants were grown in rooting medium without NaCl, acclimatized and underwent gradual salt stress : S0 - no NaCl; waterings with S1 - 20 -> 40 -> 60 mM NaCl added to the nutrient solution for 30 days. Proceeded to the suppression of NaCl and plants were evaluated after 15 days for shoot (SDM) and root dry matter (RDM), tillers number, chlorophyll estimation (Chl), relative water content and membrane damage were evaluated. The preconditioned plants did not reduce the SDM when submitted to salt stress. The effect of salt stress on the RDM was null in the plants of the priming for 24 h. Preconditioning favored the tillering of the plants of the treatments 24 or 36 h. The recovery after the stress, assessed 15 days after the removal of NaCl did not differ between whether or not subject to priming plants. According to the results the priming used in the RB98710 variety may favor tolerance to salinity.