EN
In the study, spring barley genotypes of various origin and breeding history were found to show a broad genetic variation in the vegetative and generative measures of the whole-plant transpiration efficiency (TE), photosynthesis (A) and transpiration (E) rates of flag leaves, leaf efficiency of gas exchange (A/E) and stress tolerance (T) when grown till maturity in soil-pots under high and reduced NPK supplies. Broad-sense heritabilities for the characteristics ranged from 0.61 to 0.87. Significant genotype-nutrition interactions were noticed, constituting 19-23 % of the total variance in TE measures. The results suggest that at least some ?exotic? accessions from Ethiopia, Syria, Morocco and/or Tibet may serve as attractive genetic sources of novel variations in TE, T and A for the breeding of barleys of improved adaptation to less favourable fertilisation.