The agronomic and physiological traits, drought tolerance indexes, principal component analysis and Ward`s method were applied to assess the differences among 20 wheat genotypes in response to drought. Statistically significant correlation was observed for measured traits. Drought susceptibility index (DSI), stress tolerance index (STI) and stress index (SI) were most useful to identify genotypes differing in their response to drought. Utility of the indexes was confirmed by physiological markers of drought tolerance i.e. membrane injury and leaf water status. Variation of the genotypes in biomass and grain yield during drought stress was also verified by clustering methods. Finally, integration of physiological and statistical methods presented in this work, allows to both, indicate that tolerance to drought in wheat has a common genetic background, and select the most diverse genotypes. Based on the results, we recommend a tool for breeders, useful to select the genotypes resistant and sensitive to drought.

SUMMARY The objective of this research was to investigate the differences between glaucous and non‐glaucous near‐isogenic lines (NILs) of winter rye (Secale cereale L.) in terms of epicuticular wax layer properties (weight, composition, and crystal morphology), selected physiological and biochemical responses, yield components, above‐ground biomass, and plant height under soil drought stress. An important aspect of this analysis was to examine the correlation between the above characteristics. Two different NIL pairs were tested, each consisting of a typical glaucous line and a non‐glaucous line with a recessive mutation. The drought experiment was conducted twice (2015–2016). Our study showed that wax accumulation during drought was not correlated with higher leaf hydration and glaucousness. Environmental factors had a large impact on the response of the lines to drought in individual years, both in terms of physiological and biochemical reactions, and the composition of epicuticular leaf wax. The analysed pairs displayed significantly different responses to drought. Demonstration of the correlation between the components of rye leaf wax and the physiological and biochemical parameters of rye NILs is a significant achievement of this work. Interestingly, the study showed a correlation between the wax components and the content of photosynthetic pigments and tocopherols, whose biosynthesis, similarly to the biosynthesis of wax precursors, is mainly located in chloroplasts. This suggests a relationship between wax biosynthesis and plant response to various environmental conditions and drought stress.

The development of embryos requires interaction of many endogenous hormones. The aim of the study was to determine which endogenous phytohormones are involved in the process of oat (Avena sativa L.) haploidization. Oat haploids were obtained by wide crossing with Zea mays L. The hormonal profiles of the ovaries with (OE) and without developed embryo (OWE) were compared. Phytohormone contents were measured by UHPLC coupled with mass spectrometer. The total content of indole-3acetic acid (IAA), trans-zeatin (tZ), and kinetin (KN) in OE was significantly higher than in OWE. 4-Chloroindole-3-acetic acid was detected only in OWE. There were no differences between OE and OWE in the content of gibberellins (GA 1 , GA 3 , GA 4 , GA 6 , GA 7 ) and stress hormones (abscisic, salicylic, jasmonic acids). Content of endogenous KN was highly negatively correlated with the percentage of haploid embryos, germinated haploid embryos, haploid plants on MS (in vitro), haploid plants in soil (ex vitro), and doubled haploid lines. The tZ content negatively correlated with the frequency of haploid embryo formation, germination, and haploid plants obtained in vitro, as opposed to GA 1 , which correlated positively. A positive correlation was found between IAA and tZ in OE, whereas in OWE it was a negative correlation. The profiles of phytohormones in OE and OWE were determined; however, their mode of action needs to be clarified.