Variation among wheat (Triticum easativumL.) genotypes in response to the drought stress: I – selection approaches

Abstract

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.

Detecting Salt Tolerance in Doubled Haploid Wheat Lines

“…In addition, all measured traits represent nearly equal GCV and PCV, which is acceptable, although breeders wish to obtain higher GCV than PCV [62]. Many of the traits measured in this study, and their responses to salinity stress, have been used in breeding programs to evaluate the salinity tolerance of genotypes of cereal crops [63], which is desirable if the methods are easy, quick, and inexpensive [30,32]. PCA has been used to identify the most important traits, by using the first and second principal components.…”

“…Although the factors that limit photosynthesis in salt-stressed plants have been investigated for a number of species, the mechanistic pattern of inhibition remains unclear [29].In general, the ultimate goal of breeding programs is to improve the size and stability of yield and the quality of traits under stress. To this end, methods of screening for salt tolerance within a large Agronomy 2019, 9, 211 3 of 26 number of genotypes must be quick, cheap, and easy to measure [30][31][32]. Field evaluation of salt tolerant genotypes requires more cropping seasons for screening and evaluation [33].…”

“…It is also difficult to measure root traits accurately in the field [34]. Testing the salt tolerance of genotypes in a laboratory setting, where plants are under controlled conditions in small-scale pots, can be a useful indicator, as there is a significant correlation between stress resistance observed in the field and stress resistance observed in the laboratory [32,35,36]. Important laboratory protocols for the screening of salt tolerance in crop plants include seed germination in saline media, exposure of the plant to water stress, determining control of membrane stability, and measuring leaf water content [37].…”

Variation Among Spring Wheat (Triticum aestivum L.) Genotypes in Response to the Drought Stress. II—Root System Structure

“…Drought turned out to be the most detrimental abiotic stress that limited crop yield by as much as 30-80% [45]. Scientists and breeders are gradually improving crop plant genotypes in terms of drought tolerance using both traditional selection methods and genetic engineering [26,34]. However, tolerance to drought stress is a complex feature, and finding suitable phenotypes requires time-consuming exposure of plants to simultaneously or sequentially occurring stress factors in natural conditions.…”

“…Linear correlation coefficients "r" between DSI ( [26] and Materials and Methods section) and RTC of the measured traits in the plants growing in root-box and root-basket containers were high and statistically significant ( Table 5). Contrary to that, insignificant correlation coefficients "r" were calculated for the length of seminal and seminal adventitious roots (0.605 and 0.104) and the number of roots growing at the angle of 0-30 • and 30-60 • (−0.004 and 0.543).…”