Evaluation of barley genotypes for drought adaptability: based on stress indices and comprehensive evaluation as criteria

Screening drought tolerance in potato germplasm resources in the northwestern region of China

BACKGROUND

Drought is one of the major factors affecting the growth and development of potatoes. Screening drought-tolerant potato germplasm is of great significance for drought tolerance research and the utilization of drought-tolerant germplasm resources.

RESULTS

In this study, a two-year field evaluation of drought tolerance was conducted on 31 potato germplasm resources from 2023 to 2024. The experimental treatments included normal irrigation (NI) and drought stress (DS). A total of 24 indices related to potato morphology, photosynthesis, physiology, and yield were selected for drought tolerance evaluation. All indices exhibited varying degrees of change under drought stress. Correlation analysis revealed significant correlations among the drought tolerance coefficients of the 24 measured indicators. Principal component analysis was used to transform the 24 conventional indicators into six independent and comprehensive components, with a cumulative variance contribution rate of 86.38%. Using D-value cluster analysis, the 31 potato germplasm resources were classified into five categories: strong drought tolerance, moderate drought tolerance, intermediate drought tolerance, drought-sensitive, and extremely drought-sensitive. Stepwise regression analysis indicated that the following indicators could be used as objective evaluation criteria for drought tolerance in the mid-to-late growth stages of potatoes: fresh above-ground biomass, dry above-ground biomass, fresh below-ground biomass, dry below-ground biomass, chlorophyll content, relative chlorophyll content, net photosynthetic rate, stomatal conductance, superoxide dismutase activity, number of large tubers per plant, fresh tuber weight per plant, and plot yield.

CONCLUSIONS

Among them, the strong drought-tolerant materials included Long 10, D1595-7, Lin 18, Tong 31, and D16105-14. The results of this study provide theoretical references and practical guidance for potato drought-tolerant breeding, drought tolerance mechanisms, and drought-tolerant cultivation techniques.

Phenolic compounds, antioxidant enzymes, and oxidative stress in barley (Hordeum vulgare L.) genotypes under field drought-stress conditions

Climate change has exacerbated drought, making water scarcity a significant constraint on crop production. This study aimed to evaluate drought stress responses of 21 barley cultivars and breeding lines, using various traits of leaf oxidative stress [DPPH radical scavenging, malondialdehyde (MDA), and hydrogen peroxide (H2O2)], antioxidants (enzymes and polyphenols), photosynthetic pigments and chlorophyll fluorescence (F) [carotenoid (Car), chlorophyll (Chl), Fm, F0, and Fv/Fm], relative water content (RWC), electrolyte leakage (EL), proline (Pro), protein content (PC), and grain yield. Field experiments were conducted under both normal and drought stress conditions. Significant effects of moisture conditions were observed for most of the traits, except for Chla/b, carotenoids, and EL. Syringic acid, gallic acid, chlorogenic acid, ferulic acid, ellagic acid, caffeic acid, vanillic acid, and p-coumaric acid were the prominent phenolic acids in barley genotypes. The predominant leaf flavonoids were luteolin, apigenin, and rutin. There was significant genetic variation among genotypes for all traits except Chla/b. Drought stress caused significant increases in DPPH, MDA, H2O2, total phenolic content, total flavonoid content, peroxidase, and Pro. While catalase, ascorbate peroxidase, Chla, Chlb, Tchl, Fv/Fm, F0, Fm, RWC, PC, and grain yield were significantly decreased due to water stress. These findings offer key insights into barley genotypes' drought stress response, aiding breeders in identifying key physiological and biochemical traits as markers for developing drought-tolerant cultivars.

Abundant Genetic Diversity Harbored by Traditional Naked Barley Varieties on Tibetan Plateau: Implications in Their Effective Conservation and Utilization

Naked barley (Hordeum vulgare var. nudum) is a staple food crop, contributing significantly to global food security. Understanding genetic diversity will facilitate its effective conservation and utilization. To determine genetic diversity and its distribution within and among varieties, we characterized 30 naked barley varieties from Tibet, representing the traditional, modern, and germplasm-resources-bank gene pools, by analyzing SSR molecular fingerprints. The results demonstrate abundant genetic diversity in Tibetan naked barley varieties, particularly those in the traditional gene pool that holds much more private (unique) alleles. Principal coordinates and STRUCTURE analyses indicate substantial deviation of the modern varieties from the traditional and germplasm-resources-bank varieties. A considerable amount of seed mixture is detected in the modern varieties, suggesting the practices of using mixed seeds in modern-variety cultivation. Cluster analyses further indicate the narrow genetic background of the modern varieties, likely due to the limited number of traditional/germplasm-resources-bank varieties applied in breeding. Relationships between increases in genetic diversity and sample sizes within naked barley varieties highlight the importance of effective sampling strategies for field collections. The findings from this study have important implications for the sustainable utilization and effective conservation of different types of naked barley germplasm, both in Tibet and in other regions around the world.