SUMMARY
In vitro screening of the spring durum and bread wheat F2 hybrids for water deficit resistance by the direct selection using low molecular mannitol as a stressor was conducted. It is shown that with an increase in the concentration of mannitol from 0.2 to 0.8 M in all genotypes there was the inhibition of the growth of the callus culture that indicates the toxic effect of the stress factor. It was established that the concentration of 0.6 M mannitol allows to differentiate spring wheat genotypes for water deficit.It was found that the F2 hybrid Elehiia myronivska / Krasa Polissia was most resistant to osmotic stress because calli of this genotype under selective conditions are characterized by relatively high morphogenic potential, had the highest survival rate and regenerated plants were obtained only from explants of this hybrid after cultivation on the medium containing mannitol concentration of 0.8 M. The F2 hybrid Zhizel / Lan was most susceptible to osmotic stress because mass necrosis and lack of regenerative ability were observed in its calli, under selective conditions. The genotypic dependence of processes of shoot formation in in vitro culture was observed in the spring wheat forms of studied. The formation of regenerated plants from wheat calli took place through both gemmorizogenesis and somatic embryogenesis.Plant regenerants were obtained from the induced calli and their rearing, rooting and transfer to in vivo conditions were optimized. Genotypic responses to osmotic stress in the callus culture of spring wheat were manifested by different survival rate and different regenerative ability under the action of a stress factor. The hybrid Elehiia myronivska / Krasa Polissia can be used as a valuable material for further breeding of spring wheat. The in vitro tissue culture can be used as a test system for the screening of wheat genotypes for resistance to osmotic stress. The optimized procedure of vigorous regenerated plants production of spring durum and bread wheat in in vitro callus cultures can be used in cell selection and genetic engineering experiments