Despite intensive research and breeding efforts, the physiological and quantitative genetic bases of drought tolerance are still poorly understood. The comparison of results obtained from different sources is also complex, because different testing methods may lead to controversial conclusions. This report discusses various drought stress experiments (hydroponics and in soil) in which the plant tolerance was studied at different developmental stages. Tests were performed in the germination, seedling and adult plant stages on the parental lines of five well‐known barley‐mapping populations. The results suggest that drought tolerance is a stage‐specific trait and changes during the life cycle. The effect of drought stress depended not only on the duration and intensity of water deficiency, but also on the developmental phase in which it began. To induce the same type of stress and to obtain comparable tolerance information from the replications, it is recommended that drought stress should be induced at the same growth stage. Correlations between the traits, commonly associated with improved drought resistance (high relative water content under stress, proline accumulation, osmoregulation) with stress tolerance indexes, are also presented, while the advantages and disadvantages of the most frequently used screening methods are discussed.

10 Abstract SPAD-502 (Minolta Ltd, Osaka Japan), a 11 hand-held chlorophyll meter is widely used in the 12 synchronization of N supply with actual crop demand, 13 however it is also known, that genotype and environ-14 ment may effect SPAD value. Consequently, the aim of 15 this study was to evaluate the genetic and environ-16 mental variation in SPAD value and to determine the 17 relationship between SPAD value at heading (GS 59) 18 and grain yield. Field experiments were conducted in 19 three consecutive cropping seasons between 2012 and 20 2015 in Hungary and forty winter wheat varieties were 21 tested at two nitrogen levels. Strong significant positive 22 correlation was found between grain yield and SPAD 23 values, but it was highly influenced by cultivars. The 24 proportion of the phenotypical variance explained by 25 the cultivars was different in each growing season and 26 was ranged from 12.50 to 59.04 %.