Evaluation of Ethiopian chickpea (Cicer arietinum L.) genotypes for frost tolerance

<p>Frost stress is one of the most significant abiotic factors affecting chickpea (Cicer arietinum L.) production in the Ethiopian highlands. To investigate the frost tolerance of chickpea, 673 genotypes were characterized using an augmented design at Bakelo, Debre Berhan, Ethiopia for two years. A significant (p &lt; 0.01) variability amongst genotypes was recorded for all agronomic traits considered. A considerable number of accessions better performing over the frost susceptible genotypes were identified for agronomic traits. Stem/leaf pigmented genotypes showed a better reaction for frost stress than non-pigmented genotypes. The majority of black seeded chickpea adapted well under frost stress when compared to with brown and white seeded genotypes. According to the freezing tolerance rate (FTR) and plant survival rate (SR), 83 (12.3 %) and 85 (12.6 %) genotypes were identified as frost tolerant. There was a strong correlation (p &lt; 0.01) in grain yield with FTR, SR, seed shriveling score, stem/leaf pigmentation and seed color. Based on our findings, Ethiopian chickpea landraces has a good genetic potential for frost resistance traits for use in breeding programs. </p>

Frost Stress Tolerances and Cut Roses: A Review

In order to meet the challenges of providing food to the ever increasing population of the world, there is an insistent need to boost crop yield. Unfortunately, the production of agriculture decreasing due to various environmental factors including frost and cold are very important, especially in winter. Indeed, frost is the most important abiotic problem and one of the doctrine limiting factors affecting plant growth and development in winter. Despite various obvious symptoms under frost stress, the yellowing of leaves, weak germination, curling of leaves, decreased rate of cell swelling and wilting, reduced flower opening, curling of petals leads to the cells death. This severe damage is largely due to the sensitive drying associated with freezing during frost. In addition, signal transduction is to switch on frost response genes and transcription factors to mediating stress tolerance, thus underline mechanism of frost stress and genes involve in the frost/cold stress signal network is very important for plant growth and development. In present review, plant significances in daily life and issues related to abiotic stresses such as frost and cold tolerance mechanisms are discussed.

Sorghum Root Flavonoid Chemistry, Cultivar, and Frost Stress Effects on Rhizosphere Bacteria and Fungi

Biotic stresses, including fungal infections, result in increased production of flavonoid compounds, including 3-deoxyanthocyanidins (3-DAs), in the leaf tissues of Sorghum bicolor. Our objectives were to determine whether sorghum genotypic variation influenced root flavonoid and 3-DA concentrations and rhizosphere microbial communities and to identify how these relationships were affected by abiotic stress. We evaluated root chemicals and rhizosphere microbiomes of five near-isogenic lines of sorghum before and after a late-season frost. Roots were analyzed for total flavonoids, total phenolics, 3-DA concentrations, and antioxidant activity. Amplicon sequencing of 16S ribosomal RNA genes and internal transcribed spacer regions was performed on rhizosphere soils. Concentrations of luteolinidin (a 3-DA) and total flavonoids differed between several lines before frost; however, these relationships changed after frost. Luteolinidin increased in three lines after frost, whereas total flavonoids decreased in all the lines after frost. Lines that differed in luteolinidin and total flavonoid concentrations before frost were different from those after frost. Rhizosphere community compositions also differed before and after frost but only fungal community compositions differed among sorghum lines. Bacterial community compositions were highly correlated with total flavonoid and luteolinidin concentrations. Furthermore, a greater number of bacterial taxa were correlated with total flavonoids and luteolinidin compared with fungal taxa. Collectively, this study provides evidence that plant genotypic variation influences root flavonoids and rhizosphere community composition and that these relationships are affected by frost. Plant–microbe interactions and secondary metabolite production may be important components to include for selective breeding of sorghum for frost stress tolerance.

The role of perennation traits in plant community soil frost stress responses

Background and Aims Herbaceous plants can survive periods of prolonged freezing as below-ground structures or seed, which can be insulated from cold air by soil, litter or snow. Below-ground perennial structures vary in both form and their exposure to soil frost, and this structural variation thus may be important in determining the responses of plant communities to frost stress. Methods We conducted a suite of snow removal experiments in a northern temperate old field over 3 years to examine the relative freezing responses of different plant functional groups based on below-ground perennation traits. A litter removal treatment was added in the third year. Species-level percentage cover data were recorded in May, June and September then pooled by functional group. Key Results Snow removal decreased total plant cover, and this response was particularly strong and consistent among years for tap-rooted and rhizomatous species. The snow removal responses of cover for plants with root buds and new recruits from seed varied from positive to negative among years. The cover of rootstock plants consistently increased in response to snow removal. Rhizomatous species were generally the most vulnerable to litter removal. Conclusions This study is the first to explore the effects of variation in frost severity on the responses of different plant perennation trait functional groups. The responses of herbaceous species to frost may become increasingly important in northern temperate regions in the coming decades as a result of declining snow cover and increasing temperature variability. Our results reveal substantial variation in responses among perennation trait functional groups, which could drive changes in species abundance in response to variation in soil frost.

Detecting Frost Stress in Wheat: A Controlled Environment Hyperspectral Study on Wheat Plant Components and Implications for Multispectral Field Sensing

Radiant frost during the reproductive stage of plant growth can result in considerable wheat (Triticum aestivum L.) yield loss. Much effort has been spent to prevent and manage these losses, including post-frost remote sensing of damage. This study was done under controlled conditions to examine the effect of imposed frost stress on the spectral response of wheat plant components (heads and flag leaves). The approach used hyperspectral profiling to determine whether changes in wheat components were evident immediately after a frost (up to 5 days after frosting (DAF)). Significant differences were found between frost treatments, irrespective of DAF, in the Blue/Green (419–512 nanometers (nm)), Red (610–675 nm) and Near Infrared (NIR; 749–889 nm) regions of the electromagnetic spectrum (EMS) in head spectra, and in the Blue (415–494 nm), Red (670–687 nm) and NIR (727–889 nm) regions in the leaf spectra. Significant differences were found for an interaction between time and frost treatment in the Green (544–575 nm) and NIR (756–889 nm) in head spectra, and in the UV (394–396 nm) and Green/Red (564–641 nm) in leaf spectra. These findings were compared with spectral and temporal resolutions of commonly used field agricultural multispectral sensors to examine their potential suitability for frost damage studies at the canopy scale, based on the correspondence of their multispectral bands to the results from this laboratory-based hyperspectral study.

The Possible Role of Non-Structural Carbohydrates in the Regulation of Tree Hydraulics

The xylem is a complex system that includes a network of dead conduits ensuring long-distance water transport in plants. Under ongoing climate changes, xylem embolism is a major and recurrent cause of drought-induced tree mortality. Non-structural carbohydrates (NSC) play key roles in plant responses to drought and frost stress, and several studies putatively suggest their involvement in the regulation of xylem water transport. However, a clear picture on the roles of NSCs in plant hydraulics has not been drawn to date. We summarize the current knowledge on the involvement of NSCs during embolism formation and subsequent hydraulic recovery. Under drought, sugars are generally accumulated in xylem parenchyma and in xylem sap. At drought-relief, xylem functionality is putatively restored in an osmotically driven process involving wood parenchyma, xylem sap and phloem compartments. By analyzing the published data on stem hydraulics and NSC contents under drought/frost stress and subsequent stress relief, we found that embolism build-up positively correlated to stem NSC depletion, and that the magnitude of post-stress hydraulic recovery positively correlated to consumption of soluble sugars. These findings suggest a close relationship between hydraulics and carbohydrate dynamics. We call for more experiments on hydraulic and NSC dynamics in controlled and field conditions.

Comparative study of leaf antioxidant activity as a possible mechanism for frost tolerance in ‘Hass’ and ‘Ettinger’ avocado cultivars

A major drawback of avocado (Persea americanaMill.) is susceptibility to frosts, which reduces yields and limits its geographic distribution and market growth. Whereas the frost-susceptible cultivar ‘Hass’ leads the global avocado market, cv. ‘Ettinger’, although commercially less important, is considered frost-tolerant. The mechanism behind the greater frost tolerance of ‘Ettinger’ has not yet been elucidated; therefore, the aim of the current study was to evaluate the differences between the frost responses of the two cultivars. The results showed that detached ‘Ettinger’ branches had greater tolerance than ‘Hass’ to controlled frost stress. Tissue browning caused by methyl viologen oxidative cell damage, superoxide accumulation in leaf discs following wounding and browning of cut surfaces in branches were much lower in ‘Ettinger’ than in ‘Hass’, suggesting greater antioxidant activity (AA) in the former. In leaf extracts, AA was significantly higher in ‘Ettinger’ than in ‘Hass’, but osmolarity was similar in the two cultivars. Total phenolics content was significantly higher in ‘Ettinger’ but addition of a protein mask did not significantly reduce AA in either cultivar. Interestingly, following the freezing treatment, AA increased in ‘Ettinger’ and remained almost unchanged in ‘Hass’, while osmolarity was unaffected in either cultivar. These results suggest that the greater frost-tolerance of ‘Ettinger’ than ‘Hass’ is due largely to its greater AA, which springs mainly from a non-enzymatic source, i.e. accumulation of phenolic compounds. Based on the current study, future applications may be developed to minimize frost damage in avocado orchards.